js-apis-medialibrary.md

# @ohos.multimedia.medialibrary (Media Library Management)

> **NOTE**
>
> - The APIs of this module are supported since API version 6. Updates will be marked with a superscript to indicate their earliest API version.
> - This API is deprecated since API version 9 and will be retained until API version 13.
> - Certain functionalities are changed as system APIs and can be used only by system applications. To use these functionalities, call [@ohos.filemanagement.userFileManager](js-apis-userFileManager.md).
> - The functionalities for selecting and storing media assets are still open to common applications. To use these functionalities, call [@ohos.file.picker](js-apis-file-picker.md).

## Modules to Import
```js
import mediaLibrary from '@ohos.multimedia.mediaLibrary';
```

## mediaLibrary.getMediaLibrary<sup>8+</sup>

getMediaLibrary(context: Context): MediaLibrary

Obtains a **MediaLibrary** instance, which is used to access and modify personal media data such as audios, videos, images, and documents.

This API can be used only in the stage model.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name | Type   | Mandatory| Description                      |
| ------- | ------- | ---- | -------------------------- |
| context | Context | Yes  | Context of the ability.|

**Return value**

| Type                           | Description   |
| ----------------------------- | :---- |
| [MediaLibrary](#medialibrary) | **MediaLibrary** instance.|

**Example (from API version 9)**

```ts
// Obtain a MediaLibrary instance. The instance obtained here is used in later.
const context = getContext(this);
let media = mediaLibrary.getMediaLibrary(context);
```

**Example (API version 8)**

```js
import featureAbility from '@ohos.ability.featureAbility';

let context = featureAbility.getContext();
let media = mediaLibrary.getMediaLibrary(context);
```

## mediaLibrary.getMediaLibrary

getMediaLibrary(): MediaLibrary

Obtains a **MediaLibrary** instance, which is used to access and modify personal media data such as audios, videos, images, and documents.

This API can be used only in the FA model.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type                         | Description      |
| ----------------------------- | :--------- |
| [MediaLibrary](#medialibrary) | **MediaLibrary** instance.|

**Example**

```js
let media = mediaLibrary.getMediaLibrary();
```

## MediaLibrary

### getFileAssets<sup>7+</sup>


getFileAssets(options: MediaFetchOptions, callback: AsyncCallback&lt;FetchFileResult&gt;): void 

Obtains file assets (also called files). This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name  | Type                                               | Mandatory| Description                             |
| -------- | --------------------------------------------------- | ---- | --------------------------------- |
| options  | [MediaFetchOptions](#mediafetchoptions7)            | Yes  | Options for fetching the files.                     |
| callback | AsyncCallback<[FetchFileResult](#fetchfileresult7)> | Yes  | Asynchronous callback of **FetchFileResult**.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    // Create options for fetching the files. The options are used to obtain files of the image type.
    let imagesFetchOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
    };
    // Obtain the files in asynchronous callback mode.
    media.getFileAssets(imagesFetchOp, (error, fetchFileResult) => {
        // Check whether the result set of the obtained files is undefined. If yes, the API call fails.
        if (fetchFileResult == undefined) {
            console.error('get fetchFileResult failed with error: ' + error);
            return;
        }
        // Obtain the total number of files in the result set.
        const count = fetchFileResult.getCount();
        // Check whether the number is less than 0. If yes, the API call fails.
        if (count < 0) {
            console.error('get count from fetchFileResult failed, count: ' + count);
            return;
        }
        // Check whether the number is 0. If yes, the API call is successful, but the result set is empty. Check whether the options for fetching the files are correctly set and whether the corresponding files exist on the device.
        if (count == 0) {
            console.info('The count of fetchFileResult is zero');
            return;
        }
        console.info('Get fetchFileResult successfully, count: ' + count);
        // Obtain the first file in the result set in asynchronous callback mode.
        fetchFileResult.getFirstObject((error, fileAsset) => {
            // Check whether the first file is undefined. If yes, the API call fails.
            if (fileAsset == undefined) {
                console.error('get first object failed with error: ' + error);
                return;
            }
            console.info('fileAsset.displayName ' + '0 : ' + fileAsset.displayName);
            // Call getNextObject to obtain the next file until the last one.
            for (let i = 1; i < count; i++) {
                let fileAsset = await fetchFileResult.getNextObject();
                console.info('fileAsset.displayName ' + i + ': ' + fileAsset.displayName);
            }
            // Release the FetchFileResult instance and invalidate it. Other APIs can no longer be called.
            fetchFileResult.close();
        });
    });
}
```

### getFileAssets<sup>7+</sup>

getFileAssets(options: MediaFetchOptions): Promise&lt;FetchFileResult&gt;

Obtains file assets. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name | Type                                    | Mandatory| Description        |
| ------- | ---------------------------------------- | ---- | ------------ |
| options | [MediaFetchOptions](#mediafetchoptions7) | Yes  | Options for fetching the files.|

**Return value**

| Type                                | Description          |
| ------------------------------------ | -------------- |
| [FetchFileResult](#fetchfileresult7) | Result set of the file retrieval operation.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    // Create options for fetching the files. The options are used to obtain files of the image type.
    let imagesFetchOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
    };
    // Obtain the files in promise mode.
    media.getFileAssets(imagesFetchOp).then((fetchFileResult) => {
        // Obtain the total number of files in the result set.
        const count = fetchFileResult.getCount();
        // Check whether the number is less than 0. If yes, the API call fails.
        if (count < 0) {
            console.error('get count from fetchFileResult failed, count: ' + count);
            return;
        }
        // Check whether the number is 0. If yes, the API call is successful, but the result set is empty. Check whether the options for fetching the files are correctly set and whether the corresponding files exist on the device.
        if (count == 0) {
            console.info('The count of fetchFileResult is zero');
            return;
        }
        console.info('Get fetchFileResult successfully, count: ' + count);
        // Obtain the first file in the result set in promise mode.
        fetchFileResult.getFirstObject().then((fileAsset) => {
            console.info('fileAsset.displayName ' + '0 : ' + fileAsset.displayName);
            // Call getNextObject to obtain the next file until the last one.
            for (let i = 1; i < count; i++) {
                let fileAsset = await fetchFileResult.getNextObject();
                console.info('fileAsset.displayName ' + i + ': ' + fileAsset.displayName);
            }
            // Release the FetchFileResult instance and invalidate it. Other APIs can no longer be called.
            fetchFileResult.close();
        }).catch((error) => {
            // Calling getFirstObject fails.
            console.error('get first object failed with error: ' + error);
        });
    }).catch((error) => {
        // Calling getFileAssets fails.
        console.error('get file assets failed with error: ' + error);
    });
}
```

### on<sup>8+</sup>

on(type: 'deviceChange'&#124;'albumChange'&#124;'imageChange'&#124;'audioChange'&#124;'videoChange'&#124;'fileChange'&#124;'remoteFileChange', callback: Callback&lt;void&gt;): void

Subscribes to the media library changes. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                  | Mandatory  | Description                                      |
| -------- | -------------------- | ---- | ---------------------------------------- |
| type     | 'deviceChange'&#124;<br>'albumChange'&#124;<br>'imageChange'&#124;<br>'audioChange'&#124;<br>'videoChange'&#124;<br>'fileChange'&#124;<br>'remoteFileChange'               | Yes   | Media type.<br>'deviceChange': registered device change<br>'albumChange': album change<br>'imageChange': image file change<br>'audioChange': audio file change<br>'videoChange': video file change<br>'fileChange': file change<br>'remoteFileChange': file change on the registered device|
| callback | Callback&lt;void&gt; | Yes   | Void callback.                                   |

**Example**

```js
media.on('imageChange', () => {
    // image file had changed, do something
})
```
### off<sup>8+</sup>

off(type: 'deviceChange'&#124;'albumChange'&#124;'imageChange'&#124;'audioChange'&#124;'videoChange'&#124;'fileChange'&#124;'remoteFileChange', callback?: Callback&lt;void&gt;): void

Unsubscribes from the media library changes. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                  | Mandatory  | Description                                      |
| -------- | -------------------- | ---- | ---------------------------------------- |
| type     | 'deviceChange'&#124;<br>'albumChange'&#124;<br>'imageChange'&#124;<br>'audioChange'&#124;<br>'videoChange'&#124;<br>'fileChange'&#124;<br>'remoteFileChange'               | Yes   | Media type.<br>'deviceChange': registered device change<br>'albumChange': album change<br>'imageChange': image file change<br>'audioChange': audio file change<br>'videoChange': video file change<br>'fileChange': file change<br>'remoteFileChange': file change on the registered device|
| callback | Callback&lt;void&gt; | No   | Void callback.                                   |

**Example**

```js
media.off('imageChange', () => {
    // Stop listening successfully.
})
```

### createAsset<sup>8+</sup>

createAsset(mediaType: MediaType, displayName: string, relativePath: string, callback: AsyncCallback&lt;FileAsset&gt;): void

Creates a media asset. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name      | Type                                   | Mandatory| Description                                                        |
| ------------ | --------------------------------------- | ---- | ------------------------------------------------------------ |
| mediaType    | [MediaType](#mediatype8)                | Yes  | Media type.                                                    |
| displayName  | string                                  | Yes  | Display file name.                                                  |
| relativePath | string                                  | Yes  | Path for storing the file. You can use [getPublicDirectory](#getpublicdirectory8) to obtain the paths for storing different types of files.|
| callback     | AsyncCallback<[FileAsset](#fileasset7)> | Yes  | Asynchronous callback for **FileAsset**.                         |

**Example**

```js
async function example() {
    // Create an image file in callback mode.
    let mediaType = mediaLibrary.MediaType.IMAGE;
    let DIR_IMAGE = mediaLibrary.DirectoryType.DIR_IMAGE;
    const path = await media.getPublicDirectory(DIR_IMAGE);
    media.createAsset(mediaType, 'imageCallBack.jpg', path + 'myPicture/', (error, fileAsset) => {
        if (fileAsset != undefined) {
            console.info('createAsset successfully, message');
        } else {
            console.error('createAsset failed with error: ' + error);
        }
    });
}
```

### createAsset<sup>8+</sup>

createAsset(mediaType: MediaType, displayName: string, relativePath: string): Promise&lt;FileAsset&gt;

Creates a media asset. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name      | Type                    | Mandatory| Description                                                        |
| ------------ | ------------------------ | ---- | ------------------------------------------------------------ |
| mediaType    | [MediaType](#mediatype8) | Yes  | Media type.                                                    |
| displayName  | string                   | Yes  | Display file name.                                                  |
| relativePath | string                   | Yes  | Relative path. You can use [getPublicDirectory](#getpublicdirectory8) to obtain the relative path of the level-1 directory of different types of media files.|

**Return value**

| Type                    | Description             |
| ------------------------ | ----------------- |
| [FileAsset](#fileasset7) | Media data (FileAsset).|

**Example**

```js
async function example() {
    // Create an image file in promise mode.
    let mediaType = mediaLibrary.MediaType.IMAGE;
    let DIR_IMAGE = mediaLibrary.DirectoryType.DIR_IMAGE;
    const path = await media.getPublicDirectory(DIR_IMAGE);
    media.createAsset(mediaType, 'imagePromise.jpg', path + 'myPicture/').then((fileAsset) => {
        console.info('createAsset successfully, message = ' + JSON.stringify(fileAsset));
    }).catch((error) => {
        console.error('createAsset failed with error: ' + error);
    });
}
```

### deleteAsset<sup>8+</sup>

deleteAsset(uri: string): Promise\<void>

Deletes a file asset. This API uses a promise to return the result.

**System API**: This is a system API.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                          | Mandatory  | Description             |
| -------- | ---------------------------- | ---- | --------------- |
| uri | string | Yes   | URI of the file asset to delete.|

**Return value**
| Type                 | Description                  |
| ------------------- | -------------------- |
| Promise&lt;void&gt; | Promise used to return the result.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let fileType = mediaLibrary.MediaType.FILE;
    let option = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [fileType.toString()],
    };
    const fetchFileResult = await media.getFileAssets(option);
    let asset = await fetchFileResult.getFirstObject();
    if (asset == undefined) {
        console.error('asset not exist');
        return;
    }
    media.deleteAsset(asset.uri).then(() => {
        console.info('deleteAsset successfully');
    }).catch((error) => {
        console.error('deleteAsset failed with error: ' + error);
    });
    fetchFileResult.close();
}
```

### deleteAsset<sup>8+</sup>
deleteAsset(uri: string, callback: AsyncCallback\<void>): void

Deletes a file asset. This API uses an asynchronous callback to return the result.

**System API**: This is a system API.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                          | Mandatory  | Description             |
| -------- | ---------------------------- | ---- | --------------- |
| uri | string | Yes   | URI of the file asset to delete.|
|callback |AsyncCallback\<void>| Yes |Callback used to return the result.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let fileType = mediaLibrary.MediaType.FILE;
    let option = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [fileType.toString()],
    };
    const fetchFileResult = await media.getFileAssets(option);
    let asset = await fetchFileResult.getFirstObject();
    if (asset == undefined) {
        console.error('asset not exist');
        return;
    }
    media.deleteAsset(asset.uri, (error) => {
        if (error != undefined) {
            console.error('deleteAsset failed with error: ' + error);
        } else {
            console.info('deleteAsset successfully');
        }
    });
    fetchFileResult.close();
}
```

### getPublicDirectory<sup>8+</sup>

getPublicDirectory(type: DirectoryType, callback: AsyncCallback&lt;string&gt;): void

Obtains a public directory. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name  | Type                            | Mandatory| Description                     |
| -------- | -------------------------------- | ---- | ------------------------- |
| type     | [DirectoryType](#directorytype8) | Yes  | Type of the public directory.             |
| callback | AsyncCallback&lt;string&gt;      | Yes  | Callback used to return the public directory.|

**Example**

```js
let DIR_CAMERA = mediaLibrary.DirectoryType.DIR_CAMERA;
media.getPublicDirectory(DIR_CAMERA, (error, dicResult) => {
    if (dicResult == 'Camera/') {
        console.info('getPublicDirectory DIR_CAMERA successfully');
    } else {
        console.error('getPublicDirectory DIR_CAMERA failed with error: ' + error);
    }
});
```

### getPublicDirectory<sup>8+</sup>

getPublicDirectory(type: DirectoryType): Promise&lt;string&gt;

Obtains a public directory. This API uses a promise to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name| Type                            | Mandatory| Description        |
| ------ | -------------------------------- | ---- | ------------ |
| type   | [DirectoryType](#directorytype8) | Yes  | Type of the public directory.|

**Return value**

| Type            | Description            |
| ---------------- | ---------------- |
| Promise\<string> | Promise used to return the public directory.|

**Example**

```js
async function example() {
    let DIR_CAMERA = mediaLibrary.DirectoryType.DIR_CAMERA;
    media.getPublicDirectory(DIR_CAMERA).then((dicResult) => {
        if (dicResult == 'Camera/') {
            console.info('getPublicDirectory DIR_CAMERA successfully');
        } else {
            console.error('getPublicDirectory DIR_CAMERA failed');
        }
    }).catch((error) => {
        console.error('getPublicDirectory failed with error: ' + error);
    });
}
```

### getAlbums<sup>7+</sup>

getAlbums(options: MediaFetchOptions, callback: AsyncCallback&lt;Array&lt;Album&gt;&gt;): void

Obtains the albums. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name  | Type                                        | Mandatory| Description                       |
| -------- | -------------------------------------------- | ---- | --------------------------- |
| options  | [MediaFetchOptions](#mediafetchoptions7)     | Yes  | Options for fetching the albums.               |
| callback | AsyncCallback&lt;Array<[Album](#album7)>&gt; | Yes  | Callback used to return the albums.|

**Example**

```js
async function example() {
    let AlbumNoArgsfetchOp = {
        selections: '',
        selectionArgs: [],
    };
    media.getAlbums(AlbumNoArgsfetchOp, (error, albumList) => {
        if (albumList != undefined) {
            console.info('getAlbums successfully: ' + JSON.stringify(albumList));
        } else {
            console.error('getAlbums failed with error: ' + error);
        }
    })
}
```

### getAlbums<sup>7+</sup>

getAlbums(options: MediaFetchOptions): Promise&lt;Array&lt;Album&gt;&gt;

Obtains the albums. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name | Type                                    | Mandatory| Description        |
| ------- | ---------------------------------------- | ---- | ------------ |
| options | [MediaFetchOptions](#mediafetchoptions7) | Yes  | Options for fetching the albums.|

**Return value**

| Type                            | Description         |
| -------------------------------- | ------------- |
| Promise<Array<[Album](#album7)>> | Promise used to return the albums.|

**Example**

```js
async function example() {
    let AlbumNoArgsfetchOp = {
        selections: '',
        selectionArgs: [],
    };
    media.getAlbums(AlbumNoArgsfetchOp).then((albumList) => {
        console.info('getAlbums successfully: ' + JSON.stringify(albumList));
    }).catch((error) => {
        console.error('getAlbums failed with error: ' + error);
    });
}
```

### release<sup>8+</sup>

release(callback: AsyncCallback&lt;void&gt;): void

Releases this **MediaLibrary** instance.
Call this API when you no longer need to use the APIs in the **MediaLibrary** instance.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                       | Mandatory  | Description        |
| -------- | ------------------------- | ---- | ---------- |
| callback | AsyncCallback&lt;void&gt; | Yes   | Callback that returns no value.|

**Example**

```js
media.release(() => {
    // do something
});
```

### release<sup>8+</sup>

release(): Promise&lt;void&gt;

Releases this **MediaLibrary** instance.
Call this API when you no longer need to use the APIs in the **MediaLibrary** instance.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type                 | Description                  |
| ------------------- | -------------------- |
| Promise&lt;void&gt; | Promise used to return the execution result.|

**Example**

```js
media.release()
```

### storeMediaAsset

storeMediaAsset(option: MediaAssetOption, callback: AsyncCallback&lt;string&gt;): void

Stores a media asset. This API uses an asynchronous callback to return the URI that stores the media asset.

> **NOTE**
>
> This API is supported since API version 6 and can be used only by the FA model.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                                   | Mandatory  | Description                     |
| -------- | ------------------------------------- | ---- | ----------------------- |
| option   | [MediaAssetOption](#mediaassetoption) | Yes   | Media asset option.                |
| callback | AsyncCallback&lt;string&gt;           | Yes   | Callback used to return the URI that stores the media asset.|

**Example**

```js
let option = {
    src : '/data/storage/el2/base/haps/entry/image.png',
    mimeType : 'image/*',
    relativePath : 'Pictures/'
};
mediaLibrary.getMediaLibrary().storeMediaAsset(option, (error, value) => {
    if (error) {
        console.error('storeMediaAsset failed with error: ' + error);
        return;
    }
    console.info('Media resources stored. ');
    // Obtain the URI that stores the media asset.
});
```


### storeMediaAsset

storeMediaAsset(option: MediaAssetOption): Promise&lt;string&gt;

Stores a media asset. This API uses a promise to return the URI that stores the media asset.

> **NOTE**
>
> This API is supported since API version 6 and can be used only by the FA model.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name   | Type                                   | Mandatory  | Description     |
| ------ | ------------------------------------- | ---- | ------- |
| option | [MediaAssetOption](#mediaassetoption) | Yes   | Media asset option.|

**Return value**

| Type                   | Description                          |
| --------------------- | ---------------------------- |
| Promise&lt;string&gt; | Promise used to return the URI that stores the media asset.|

**Example**

```js
let option = {
    src : '/data/storage/el2/base/haps/entry/image.png',
    mimeType : 'image/*',
    relativePath : 'Pictures/'
};
mediaLibrary.getMediaLibrary().storeMediaAsset(option).then((value) => {
    console.info('Media resources stored.');
    // Obtain the URI that stores the media asset.
}).catch((error) => {
    console.error('storeMediaAsset failed with error: ' + error);
});
```


### startImagePreview

startImagePreview(images: Array&lt;string&gt;, index: number, callback: AsyncCallback&lt;void&gt;): void

Starts image preview, with the first image to preview specified. This API can be used to preview local images whose URIs start with **datashare://** or online images whose URIs start with **https://**. It uses an asynchronous callback to return the execution result.

> **NOTE**
> This API is supported since API version 6 and can be used only by the FA model.
> You are advised to use the **\<[Image](../arkui-ts/ts-basic-components-image.md)>** component instead. The **\<Image>** component can be used to render and display local and online images.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                       | Mandatory  | Description                                      |
| -------- | ------------------------- | ---- | ---------------------------------------- |
| images   | Array&lt;string&gt;       | Yes   | URIs of the images to preview. The value can start with either **'https://'** or **'datashare://'**.|
| index    | number                    | Yes   | Index of the first image to preview.                              |
| callback | AsyncCallback&lt;void&gt; | Yes   | Callback used to return the image preview result. If the preview fails, an error message is returned.                       |

**Example**

```js
let images = [
    'datashare:///media/xxxx/2',
    'datashare:///media/xxxx/3'
];
/* Preview online images.
let images = [
    'https://media.xxxx.com/image1.jpg',
    'https://media.xxxx.com/image2.jpg'
];
*/
let index = 1;
mediaLibrary.getMediaLibrary().startImagePreview(images, index, (error) => {
    if (error) {
        console.error('startImagePreview failed with error: ' + error);
        return;
    }
    console.info('Succeeded in previewing the images.');
});
```


### startImagePreview

startImagePreview(images: Array&lt;string&gt;, callback: AsyncCallback&lt;void&gt;): void

Starts image preview. This API can be used to preview local images whose URIs start with **datashare://** or online images whose URIs start with **https://**. It uses an asynchronous callback to return the execution result.

> **NOTE**
> This API is supported since API version 6 and can be used only by the FA model.
> You are advised to use the **\<[Image](../arkui-ts/ts-basic-components-image.md)>** component instead. The **\<Image>** component can be used to render and display local and online images.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                       | Mandatory  | Description                                      |
| -------- | ------------------------- | ---- | ---------------------------------------- |
| images   | Array&lt;string&gt;       | Yes   | URIs of the images to preview. The value can start with either **'https://'** or **'datashare://'**.|
| callback | AsyncCallback&lt;void&gt; | Yes   | Callback used to return the image preview result. If the preview fails, an error message is returned.                       |

**Example**

```js
let images = [
    'datashare:///media/xxxx/2',
    'datashare:///media/xxxx/3'
];
/* Preview online images.
let images = [
    'https://media.xxxx.com/image1.jpg',
    'https://media.xxxx.com/image2.jpg'
];
*/
mediaLibrary.getMediaLibrary().startImagePreview(images, (error) => {
    if (error) {
        console.error('startImagePreview failed with error: ' + error);
        return;
    }
    console.info('Succeeded in previewing the images.');
});
```


### startImagePreview

startImagePreview(images: Array&lt;string&gt;, index?: number): Promise&lt;void&gt;

Starts image preview, with the first image to preview specified. This API can be used to preview local images whose URIs start with **datashare://** or online images whose URIs start with **https://**. It uses a promise to return the execution result.

> **NOTE**
> This API is supported since API version 6 and can be used only by the FA model.
> You are advised to use the **\<[Image](../arkui-ts/ts-basic-components-image.md)>** component instead. The **\<Image>** component can be used to render and display local and online images.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name   | Type                 | Mandatory  | Description                                      |
| ------ | ------------------- | ---- | ---------------------------------------- |
| images | Array&lt;string&gt; | Yes   | URIs of the images to preview. The value can start with either **'https://'** or **'datashare://'**.|
| index  | number              | No   | Index of the first image to preview. If this parameter is not specified, the default value **0** is used.                     |

**Return value**

| Type                 | Description                             |
| ------------------- | ------------------------------- |
| Promise&lt;void&gt; | Promise used to return the image preview result. If the preview fails, an error message is returned.|

**Example**

```js
let images = [
    'datashare:///media/xxxx/2',
    'datashare:///media/xxxx/3'
];
/* Preview online images.
let images = [
    'https://media.xxxx.com/image1.jpg',
    'https://media.xxxx.com/image2.jpg'
];
*/
let index = 1;
mediaLibrary.getMediaLibrary().startImagePreview(images, index).then(() => {
    console.info('Succeeded in previewing the images.');
}).catch((error) => {
    console.error('startImagePreview failed with error: ' + error);
});
```


### startMediaSelect

startMediaSelect(option: MediaSelectOption, callback: AsyncCallback&lt;Array&lt;string&gt;&gt;): void

Starts media selection. This API uses an asynchronous callback to return the list of URIs that store the selected media assets.

> **NOTE**
> This API is supported since API version 6 and can be used only by the FA model.
> You are advised to use the system app Gallery instead. Gallery is a built-in visual resource access application that provides features such as image and video management and browsing. For details about how to use Gallery, visit [OpenHarmony/applications_photos](https://gitee.com/openharmony/applications_photos).

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                                      | Mandatory  | Description                                  |
| -------- | ---------------------------------------- | ---- | ------------------------------------ |
| option   | [MediaSelectOption](#mediaselectoption)  | Yes   | Media selection option.                             |
| callback | AsyncCallback&lt;Array&lt;string&gt;&gt; | Yes   | Callback used to return the list of URIs (starting with **datashare://**) that store the selected media assets.|

**Example**

```js
let option : mediaLibrary.MediaSelectOption = {
    type : 'media',
    count : 2
};
mediaLibrary.getMediaLibrary().startMediaSelect(option, (error, value) => {
    if (error) {
        console.error('startMediaSelect failed with error: ' + error);
        return;
    }
    console.info('Media resources selected.');
    // Obtain the media selection value.
});
```


### startMediaSelect

startMediaSelect(option: MediaSelectOption): Promise&lt;Array&lt;string&gt;&gt;

Starts media selection. This API uses a promise to return the list of URIs that store the selected media assets.

> **NOTE**
> This API is supported since API version 6 and can be used only by the FA model.
> You are advised to use the system app Gallery instead. Gallery is a built-in visual resource access application that provides features such as image and video management and browsing. For details about how to use Gallery, visit [OpenHarmony/applications_photos](https://gitee.com/openharmony/applications_photos).

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name   | Type                                     | Mandatory  | Description     |
| ------ | --------------------------------------- | ---- | ------- |
| option | [MediaSelectOption](#mediaselectoption) | Yes   | Media selection option.|

**Return value**

| Type                                | Description                                      |
| ---------------------------------- | ---------------------------------------- |
| Promise&lt;Array&lt;string&gt;&gt; | Promise used to return the list of URIs (starting with **datashare://**) that store the selected media assets.|

**Example**

```js
let option : mediaLibrary.MediaSelectOption = {
    type : 'media',
    count : 2
};
mediaLibrary.getMediaLibrary().startMediaSelect(option).then((value) => {
    console.info('Media resources selected.');
    // Obtain the media selection value.
}).catch((error) => {
    console.error('startMediaSelect failed with error: ' + error);
});

```
### getActivePeers<sup>8+</sup>

getActivePeers(): Promise\<Array\<PeerInfo>>;

Obtains information about online peer devices. This API uses a promise to return the result.

**System API**: This is a system API.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.DistributedCore

**Return value**

| Type                 | Description                  |
| ------------------- | -------------------- |
|  Promise\<Array\<[PeerInfo](#peerinfo8)>> | Promise used to return the online peer devices, in an array of **PeerInfo** objects.|

**Example**

```js
async function example() {
    media.getActivePeers().then((devicesInfo) => {
        if (devicesInfo != undefined) {
            console.info('get distributed info ' + JSON.stringify(devicesInfo));
        } else {
            console.info('get distributed info is undefined!');
        }
    }).catch((error) => {
        console.error('get distributed info failed with error: ' + error);
    });
}
```

### getActivePeers<sup>8+</sup>

getActivePeers(callback: AsyncCallback\<Array\<PeerInfo>>): void;

Obtains information about online peer devices. This API uses an asynchronous callback to return the result.

**System API**: This is a system API.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.DistributedCore

**Return value**

| Type                 | Description                  |
| ------------------- | -------------------- |
| callback: AsyncCallback\<Array\<[PeerInfo](#peerinfo8)>> | Promise used to return the online peer devices, in an array of **PeerInfo** objects.|

**Example**

```js
async function example() {
    media.getActivePeers((error, devicesInfo) => {
        if (devicesInfo != undefined) {
            console.info('get distributed info ' + JSON.stringify(devicesInfo));
        } else {
            console.error('get distributed failed with error: ' + error);
        }
    });
}
```


### getAllPeers<sup>8+</sup>

getAllPeers(): Promise\<Array\<PeerInfo>>;

Obtains information about all peer devices. This API uses a promise to return the result.

**System API**: This is a system API.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.DistributedCore

**Return value**

| Type                 | Description                  |
| ------------------- | -------------------- |
|  Promise\<Array\<[PeerInfo](#peerinfo8)>> | Promise used to return all peer devices, in an array of **PeerInfo** objects.|

**Example**

```js
async function example() {
    media.getAllPeers().then((devicesInfo) => {
        if (devicesInfo != undefined) {
            console.info('get distributed info ' + JSON.stringify(devicesInfo));
        } else {
            console.info('get distributed info is undefined!');
        }
    }).catch((error) => {
        console.error('get distributed info failed with error: ' + error);
    });
}
```

### getAllPeers<sup>8+</sup>

getAllPeers(callback: AsyncCallback\<Array\<PeerInfo>>): void;

Obtains information about online peer devices. This API uses an asynchronous callback to return the result.

**System API**: This is a system API.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.DistributedCore

**Return value**

| Type                 | Description                  |
| ------------------- | -------------------- |
| callback: AsyncCallback\<Array\<[PeerInfo](#peerinfo8)>> | Promise used to return all peer devices, in an array of **PeerInfo** objects.|

**Example**

```js
async function example() {
    media.getAllPeers((error, devicesInfo) => {
        if (devicesInfo != undefined) {
            console.info('get distributed info ' + JSON.stringify(devicesInfo));
        } else {
            console.error('get distributed failed with error: ' + error);
        }
    });
}
```

## FileAsset<sup>7+</sup>

Provides APIs for encapsulating file asset attributes.

> **NOTE**
> 1. The system attempts to parse the file content if the file is an audio or video file. The actual field values will be restored from the passed values during scanning on some devices.
> 2. Some devices may not support the modification of **orientation**. You are advised to use [ModifyImageProperty](js-apis-image.md#modifyimageproperty9) of the **image** module.

### Attributes

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

| Name                     | Type                    | Readable| Writable| Description                                                  |
| ------------------------- | ------------------------ | ---- | ---- | ------------------------------------------------------ |
| id                        | number                   | Yes  | No  | File asset ID.                                          |
| uri                       | string                   | Yes  | No  | File asset URI, for example, **datashare:///media/image/2**.        |
| mimeType                  | string                   | Yes  | No  | Extended file attributes.                                          |
| mediaType<sup>8+</sup>    | [MediaType](#mediatype8) | Yes  | No  | Media type.                                              |
| displayName               | string                   | Yes  | Yes  | Display file name, including the file name extension.                                |
| title                     | string                   | Yes  | Yes  | Title in the file. By default, it carries the file name without extension.                                              |
| relativePath<sup>8+</sup> | string                   | Yes  | Yes  | Relative public directory of the file.                                      |
| parent<sup>8+</sup>       | number                   | Yes  | No  | Parent directory ID.                                              |
| size                      | number                   | Yes  | No  | File size, in bytes.                                |
| dateAdded                 | number                   | Yes  | No  | Date when the file was added. The value is the number of seconds elapsed since the Epoch time.        |
| dateModified              | number                   | Yes  | No  | Date when the file content (not the file name) was last modified. The value is the number of seconds elapsed since the Epoch time.|
| dateTaken                 | number                   | Yes  | No  | Date when the file (photo) was taken. The value is the number of seconds elapsed since the Epoch time.        |
| artist<sup>8+</sup>       | string                   | Yes  | No  | Artist of the file.                                                  |
| audioAlbum<sup>8+</sup>   | string                   | Yes  | No  | Audio album.                                                  |
| width                     | number                   | Yes  | No  | Image width, in pixels.                                |
| height                    | number                   | Yes  | No  | Image height, in pixels.                                |
| orientation               | number                   | Yes  | Yes  | Image display direction (clockwise rotation angle, for example, 0, 90, or 180, in degrees).|
| duration<sup>8+</sup>     | number                   | Yes  | No  | Duration, in ms.                                  |
| albumId                   | number                   | Yes  | No  | ID of the album to which the file belongs.                                  |
| albumUri<sup>8+</sup>     | string                   | Yes  | No  | URI of the album to which the file belongs.                                     |
| albumName                 | string                   | Yes  | No  | Name of the album to which the file belongs.                                    |


### isDirectory<sup>8+</sup>

isDirectory(callback: AsyncCallback&lt;boolean&gt;): void

Checks whether this file asset is a directory. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                          | Mandatory  | Description                 |
| -------- | ---------------------------- | ---- | ------------------- |
| callback | AsyncCallback&lt;boolean&gt; | Yes   | Callback used to return whether the file asset is a directory.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.isDirectory((error, isDirectory) => {
        if (error) {
            console.error('isDirectory failed with error: ' + error);
        } else {
            console.info('isDirectory result:' + isDirectory);
        }
    });
    fetchFileResult.close();
}
```

### isDirectory<sup>8+</sup>

isDirectory():Promise&lt;boolean&gt;

Checks whether this file asset is a directory. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type                    | Description                          |
| ---------------------- | ---------------------------- |
| Promise&lt;boolean&gt; | Promise used to return whether the file asset is a directory.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.isDirectory().then((isDirectory) => {
        console.info('isDirectory result:' + isDirectory);
    }).catch((error) => {
        console.error('isDirectory failed with error: ' + error);
    });
    fetchFileResult.close();
}
```

### commitModify<sup>8+</sup>

commitModify(callback: AsyncCallback&lt;void&gt;): void

Commits the modification in this file asset to the database. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                       | Mandatory  | Description   |
| -------- | ------------------------- | ---- | ----- |
| callback | AsyncCallback&lt;void&gt; | Yes   | Void callback.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.title = 'newtitle';
    asset.commitModify(() => {
        console.info('commitModify successfully');   
    });
    fetchFileResult.close();
}
```

### commitModify<sup>8+</sup>

commitModify(): Promise&lt;void&gt;

Commits the modification in this file asset to the database. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type                 | Description        |
| ------------------- | ---------- |
| Promise&lt;void&gt; | Void promise.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.title = 'newtitle';
    await asset.commitModify();
    fetchFileResult.close();
}
```

### open<sup>8+</sup>

open(mode: string, callback: AsyncCallback&lt;number&gt;): void

Opens this file asset. This API uses an asynchronous callback to return the result.

**NOTE**: When a file is opened in 'w' mode, the returned FD cannot be read. However, due to the implementation differences of file systems, some user-mode files opened in 'w' mode can be read by using FD. To perform the read or write operation on a file by using FD, you are advised to open the file in 'rw' mode. The write operations are mutually exclusive. After a write operation is complete, you must call **close** to release the resource.

**Required permissions**: ohos.permission.READ_MEDIA or ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                         | Mandatory  | Description                                 |
| -------- | --------------------------- | ---- | ----------------------------------- |
| mode     | string                      | Yes   | Mode of opening the file, for example, **'r'** (read-only), **'w'** (write-only), and **'rw'** (read-write).|
| callback | AsyncCallback&lt;number&gt; | Yes   | Callback used to return the file descriptor.                           |

**Example**

```js
async function example() {
    let mediaType = mediaLibrary.MediaType.IMAGE;
    let DIR_IMAGE = mediaLibrary.DirectoryType.DIR_IMAGE;
    const path = await media.getPublicDirectory(DIR_IMAGE);
    const asset = await media.createAsset(mediaType, 'image00003.jpg', path);
    asset.open('rw', (error, fd) => {
        if (fd > 0) {
            asset.close(fd);
        } else {
            console.error('File Open failed with error: ' + error);
        }
    });
}
```

### open<sup>8+</sup>

open(mode: string): Promise&lt;number&gt;

Opens this file asset. This API uses a promise to return the result.

**NOTE**: When a file is opened in 'w' mode, the returned FD cannot be read. However, due to the implementation differences of file systems, some user-mode files opened in 'w' mode can be read by using FD. To perform the read or write operation on a file by using FD, you are advised to open the file in 'rw' mode. The write operations are mutually exclusive. After a write operation is complete, you must call **close** to release the resource.

**Required permissions**: ohos.permission.READ_MEDIA or ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name | Type    | Mandatory  | Description                                 |
| ---- | ------ | ---- | ----------------------------------- |
| mode | string | Yes   | Mode of opening the file, for example, **'r'** (read-only), **'w'** (write-only), and **'rw'** (read-write).|

**Return value**

| Type                   | Description           |
| --------------------- | ------------- |
| Promise&lt;number&gt; | Promise used to return the file descriptor.|

**Example**

```js
async function example() {
    let mediaType = mediaLibrary.MediaType.IMAGE;
    let DIR_IMAGE = mediaLibrary.DirectoryType.DIR_IMAGE;
    const path = await media.getPublicDirectory(DIR_IMAGE);
    const asset = await media.createAsset(mediaType, 'image00003.jpg', path);
    asset.open('rw').then((fd) => {
        console.info('File open fd: ' + fd);
    }).catch((error) => {
        console.error('File open failed with error: ' + error);
    });
}
```

### close<sup>8+</sup>

close(fd: number, callback: AsyncCallback&lt;void&gt;): void

Closes this file asset. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA or ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                       | Mandatory  | Description   |
| -------- | ------------------------- | ---- | ----- |
| fd       | number                    | Yes   | File descriptor.|
| callback | AsyncCallback&lt;void&gt; | Yes   | Void callback.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.open('rw').then((fd) => {
        console.info('File open fd: ' + fd);
        asset.close(fd, (error) => {
            if (error) {
                console.error('asset.close failed with error: ' + error);
            } else {
                console.info('asset.close successfully');
            }
        });
    }).catch((error) => {
        console.error('File open failed with error: ' + error);
    });
    fetchFileResult.close();
}
```

### close<sup>8+</sup>

close(fd: number): Promise&lt;void&gt;

Closes this file asset. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA or ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name | Type    | Mandatory  | Description   |
| ---- | ------ | ---- | ----- |
| fd   | number | Yes   | File descriptor.|

**Return value**

| Type                 | Description        |
| ------------------- | ---------- |
| Promise&lt;void&gt; | Void promise.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.open('rw').then((fd) => {
        console.info('File fd!' + fd);
        asset.close(fd).then(() => {
            console.info('asset.close successfully');
        }).catch((closeErr) => {
            console.error('asset.close fail, closeErr: ' + closeErr);
        });
    }).catch((error) => {
        console.error('open File failed with error: ' + error);
    });
    fetchFileResult.close();
}
```

### getThumbnail<sup>8+</sup>

getThumbnail(callback: AsyncCallback&lt;image.PixelMap&gt;): void

Obtains the thumbnail of this file asset. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                                 | Mandatory  | Description              |
| -------- | ----------------------------------- | ---- | ---------------- |
| callback | AsyncCallback&lt;image.PixelMap&gt; | Yes   | Callback used to return the pixel map of the thumbnail.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.getThumbnail((error, pixelmap) => {
        if (error) {
            console.error('mediaLibrary getThumbnail failed with error: ' + error);
        } else {
            console.info('mediaLibrary getThumbnail Successful, pixelmap ' + JSON.stringify(pixelmap));
        }
    });
    fetchFileResult.close();
}
```

### getThumbnail<sup>8+</sup>

getThumbnail(size: Size, callback: AsyncCallback&lt;image.PixelMap&gt;): void

Obtains the thumbnail of this file asset, with the thumbnail size passed. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                                 | Mandatory  | Description              |
| -------- | ----------------------------------- | ---- | ---------------- |
| size     | [Size](#size8)                      | Yes   | Size of the thumbnail.           |
| callback | AsyncCallback&lt;image.PixelMap&gt; | Yes   | Callback used to return the pixel map of the thumbnail.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let size = { width: 720, height: 720 };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.getThumbnail(size, (error, pixelmap) => {
        if (error) {
            console.error('mediaLibrary getThumbnail failed with error: ' + error);
        } else {
            console.info('mediaLibrary getThumbnail Successful, pixelmap ' + JSON.stringify(pixelmap));
        }
    });
    fetchFileResult.close();
}
```

### getThumbnail<sup>8+</sup>

getThumbnail(size?: Size): Promise&lt;image.PixelMap&gt;

Obtains the thumbnail of this file asset, with the thumbnail size passed. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name | Type            | Mandatory  | Description   |
| ---- | -------------- | ---- | ----- |
| size | [Size](#size8) | No   | Size of the thumbnail.|

**Return value**

| Type                           | Description                   |
| ----------------------------- | --------------------- |
| Promise&lt;image.PixelMap&gt; | Promise to return the pixel map of the thumbnail.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let size = { width: 720, height: 720 };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.getThumbnail(size).then((pixelmap) => {
        console.info('mediaLibrary getThumbnail Successful, pixelmap ' + JSON.stringify(pixelmap));
    }).catch((error) => {
        console.error('mediaLibrary getThumbnail failed with error: ' + error);
    });
    fetchFileResult.close();
}
```

### favorite<sup>8+</sup>

favorite(isFavorite: boolean, callback: AsyncCallback&lt;void&gt;): void

Favorites or unfavorites this file asset. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name       | Type                       | Mandatory  | Description                                |
| ---------- | ------------------------- | ---- | ---------------------------------- |
| isFavorite | boolean                   | Yes   | Whether to favorite or unfavorite the file. The value **true** means to favorite the file, and **false** means to unfavorite the file.|
| callback   | AsyncCallback&lt;void&gt; | Yes   | Void callback.                             |

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.favorite(true,(error) => {
        if (error) {
            console.error('mediaLibrary favorite failed with error: ' + error);
        } else {
            console.info('mediaLibrary favorite Successful');
        }
    });
    fetchFileResult.close();
}
```

### favorite<sup>8+</sup>

favorite(isFavorite: boolean): Promise&lt;void&gt;

Favorites or unfavorites this file asset. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name       | Type     | Mandatory  | Description                                |
| ---------- | ------- | ---- | ---------------------------------- |
| isFavorite | boolean | Yes   | Whether to favorite or unfavorite the file. The value **true** means to favorite the file, and **false** means to unfavorite the file.|

**Return value**

| Type                 | Description        |
| ------------------- | ---------- |
| Promise&lt;void&gt; | Void promise.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.favorite(true).then(() => {
        console.info('mediaLibrary favorite Successful');
    }).catch((error) => {
        console.error('mediaLibrary favorite failed with error: ' + error);
    });
    fetchFileResult.close();
}
```

### isFavorite<sup>8+</sup>

isFavorite(callback: AsyncCallback&lt;boolean&gt;): void

Checks whether this file asset is favorited. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                          | Mandatory  | Description         |
| -------- | ---------------------------- | ---- | ----------- |
| callback | AsyncCallback&lt;boolean&gt; | Yes   | Callback used to return whether the file asset is favorited.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.isFavorite((error, isFavorite) => {
        if (error) {
            console.error('mediaLibrary favoriisFavoritete failed with error: ' + error);
        } else {
            console.info('mediaLibrary isFavorite Successful, isFavorite result: ' + isFavorite);
        }
    });
    fetchFileResult.close();
}
```

### isFavorite<sup>8+</sup>

isFavorite():Promise&lt;boolean&gt;

Checks whether this file asset is favorited. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type                    | Description                |
| ---------------------- | ------------------ |
| Promise&lt;boolean&gt; | Promise used to return whether the file asset is favorited.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.isFavorite().then((isFavorite) => {
        console.info('mediaLibrary isFavorite Successful, isFavorite result: ' + isFavorite);
    }).catch((error) => {
        console.error('mediaLibrary favoriisFavoritete failed with error: ' + error);
    });
    fetchFileResult.close();
}
```

### trash<sup>8+</sup>

trash(isTrash: boolean, callback: AsyncCallback&lt;void&gt;): void

Moves this file asset to the trash. This API uses an asynchronous callback to return the result.

Files in the trash are not actually deleted. You can set **isTrash** to **false** to restore the files from the trash.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                       | Mandatory  | Description       |
| -------- | ------------------------- | ---- | --------- |
| isTrash  | boolean                   | Yes   | Whether to move the file asset to the trash. The value **true** means to move the file asset to the trash, and **false** means the opposite.|
| callback | AsyncCallback&lt;void&gt; | Yes   | Void callback.    |

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.trash(true, (error) => {
        if (error) {
            console.error('mediaLibrary trash failed with error: ' + error);
        } else {
            console.info('mediaLibrary trash Successful');
        }
    });
    fetchFileResult.close();
}
```

### trash<sup>8+</sup>

trash(isTrash: boolean): Promise&lt;void&gt;

Moves this file asset to the trash. This API uses a promise to return the result.

Files in the trash are not actually deleted. You can set **isTrash** to **false** to restore the files from the trash.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name    | Type     | Mandatory  | Description       |
| ------- | ------- | ---- | --------- |
| isTrash | boolean | Yes   | Whether to move the file asset to the trash. The value **true** means to move the file asset to the trash, and **false** means the opposite.|

**Return value**

| Type                 | Description        |
| ------------------- | ---------- |
| Promise&lt;void&gt; | Void promise.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.trash(true).then(() => {
        console.info('trash successfully');
    }).catch((error) => {
        console.error('trash failed with error: ' + error);
    });
    fetchFileResult.close();
}
```

### isTrash<sup>8+</sup>

isTrash(callback: AsyncCallback&lt;boolean&gt;): void

Checks whether this file asset is in the trash. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name     | Type                          | Mandatory  | Description             |
| -------- | ---------------------------- | ---- | --------------- |
| callback | AsyncCallback&lt;boolean&gt; | Yes   | Callback used to return whether the file asset is in the trash. If the file asset is in the trash, **true** will be returned; otherwise, **false** will be returned.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.isTrash((error, isTrash) => {
        if (error) {
            console.error('Failed to get trash state failed with error: ' + error);
            return;
        }
        console.info('Get trash state successfully, isTrash result: ' + isTrash);
    });
    fetchFileResult.close();
}
```

### isTrash<sup>8+</sup>

isTrash():Promise&lt;boolean&gt;

Checks whether this file asset is in the trash. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type                 | Description                  |
| ------------------- | -------------------- |
| Promise&lt;void&gt; | Promise used to return whether the file asset is in the trash. If the file asset is in the trash, **true** will be returned; otherwise, **false** will be returned.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    const fetchFileResult = await media.getFileAssets(getImageOp);
    const asset = await fetchFileResult.getFirstObject();
    asset.isTrash().then((isTrash) => {
        console.info('isTrash result: ' + isTrash);
    }).catch((error) => {
        console.error('isTrash failed with error: ' + error);
    });
    fetchFileResult.close();
}
```

## FetchFileResult<sup>7+</sup>

Implements the result set of the file retrieval operation.

### getCount<sup>7+</sup>

getCount(): number

Obtains the total number of files in the result set.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type    | Description      |
| ------ | -------- |
| number | Total number of files.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let fileType = mediaLibrary.MediaType.FILE;
    let getFileCountOneOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [fileType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getFileCountOneOp);
    const fetchCount = fetchFileResult.getCount();
    console.info('fetchCount result: ' + fetchCount);
    fetchFileResult.close();
}
```

### isAfterLast<sup>7+</sup>

isAfterLast(): boolean

Checks whether the cursor is in the last row of the result set.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type     | Description                                |
| ------- | ---------------------------------- |
| boolean | Returns **true** if the cursor is in the last row of the result set; returns *false* otherwise.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    const fetchCount = fetchFileResult.getCount();
    console.info('mediaLibrary fetchFileResult.getCount, count:' + fetchCount);
    let fileAsset = await fetchFileResult.getFirstObject();
    for (var i = 1; i < fetchCount; i++) {
        fileAsset = await fetchFileResult.getNextObject();
        if(i == fetchCount - 1) {
            var result = fetchFileResult.isAfterLast();
            console.info('mediaLibrary fileAsset isAfterLast result: ' + result);
            fetchFileResult.close();
        }
    }
}
```

### close<sup>7+</sup>

close(): void

Releases and invalidates this **FetchFileResult** instance. Other APIs in this instance cannot be invoked after it is released.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    fetchFileResult.close();
}
```

### getFirstObject<sup>7+</sup>

getFirstObject(callback: AsyncCallback&lt;FileAsset&gt;): void

Obtains the first file asset in the result set. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name  | Type                                         | Mandatory| Description                                       |
| -------- | --------------------------------------------- | ---- | ------------------------------------------- |
| callback | AsyncCallback&lt;[FileAsset](#fileasset7)&gt; | Yes  | Callback used to return the first file asset.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    fetchFileResult.getFirstObject((error, fileAsset) => {
        if (error) {
            console.error('fetchFileResult getFirstObject failed with error: ' + error);
            return;
        }
        console.info('getFirstObject successfully, displayName : ' + fileAsset.displayName);
        fetchFileResult.close();
    })
}
```

### getFirstObject<sup>7+</sup>

getFirstObject(): Promise&lt;FileAsset&gt;

Obtains the first file asset in the result set. This API uses a promise to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type                                   | Description                      |
| --------------------------------------- | -------------------------- |
| Promise&lt;[FileAsset](#fileasset7)&gt; | Promise used to return the file asset.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    fetchFileResult.getFirstObject().then((fileAsset) => {
        console.info('getFirstObject successfully, displayName: ' + fileAsset.displayName);
        fetchFileResult.close();
    }).catch((error) => {
        console.error('getFirstObject failed with error: ' + error);
    });
}
```

### getNextObject<sup>7+</sup>

 getNextObject(callback: AsyncCallback&lt;FileAsset&gt;): void

Obtains the next file asset in the result set. This API uses an asynchronous callback to return the result.
> **NOTE** 
> 
> Before using this API, you must use [getFirstObject](#getfirstobject7) to obtain the first file asset and then use [isAfterLast](#isafterlast7) to ensure that the cursor does not point to the last file asset in the result set.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name   | Type                                         | Mandatory| Description                                     |
| --------- | --------------------------------------------- | ---- | ----------------------------------------- |
| callback| AsyncCallback&lt;[FileAsset](#fileasset7)&gt; | Yes  | Callback used to return the next file asset.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    let fileAsset = await fetchFileResult.getFirstObject();
    if (!fileAsset.isAfterLast) {
        fetchFileResult.getNextObject((error, fileAsset) => {
            if (error) {
                console.error('fetchFileResult getNextObject failed with error: ' + error);
                return;
            }
            console.log('fetchFileResult getNextObject successfully, displayName: ' + fileAsset.displayName);
            fetchFileResult.close();
        })
    }
}

```

### getNextObject<sup>7+</sup>

 getNextObject(): Promise&lt;FileAsset&gt;

Obtains the next file asset in the result set. This API uses a promise to return the result.
> **NOTE** 
> 
> Before using this API, you must use [getFirstObject](#getfirstobject7) to obtain the first file asset and then use [isAfterLast](#isafterlast7) to ensure that the cursor does not point to the last file asset in the result set.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type                                   | Description             |
| --------------------------------------- | ----------------- |
| Promise&lt;[FileAsset](#fileasset7)&gt; | Promise used to return the next file asset.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    let fileAsset = await fetchFileResult.getFirstObject();
    if (!fileAsset.isAfterLast) {
        fetchFileResult.getNextObject().then((fileAsset) => {
            console.info('fetchFileResult getNextObject successfully, displayName: ' + fileAsset.displayName);
            fetchFileResult.close();
        }).catch((error) => {
            console.error('fetchFileResult getNextObject failed with error: ' + error);
        })
    }
}
```

### getLastObject<sup>7+</sup>

getLastObject(callback: AsyncCallback&lt;FileAsset&gt;): void

Obtains the last file asset in the result set. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name  | Type                                         | Mandatory| Description                       |
| -------- | --------------------------------------------- | ---- | --------------------------- |
| callback | AsyncCallback&lt;[FileAsset](#fileasset7)&gt; | Yes  | Callback used to return the last file asset.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    fetchFileResult.getLastObject((error, fileAsset) => {
        if (error) {
            console.error('getLastObject failed with error: ' + error);
            return;
        }
        console.info('getLastObject successfully, displayName: ' + fileAsset.displayName);
        fetchFileResult.close();
    })
}
```

### getLastObject<sup>7+</sup>

getLastObject(): Promise&lt;FileAsset&gt;

Obtains the last file asset in the result set. This API uses a promise to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type                                   | Description             |
| --------------------------------------- | ----------------- |
| Promise&lt;[FileAsset](#fileasset7)&gt; | Promise used to return the next file asset.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    fetchFileResult.getLastObject().then((fileAsset) => {
        console.info('getLastObject successfully, displayName: ' + fileAsset.displayName);
        fetchFileResult.close();
    }).catch((error) => {
        console.error('getLastObject failed with error: ' + error);
    });
}
```

### getPositionObject<sup>7+</sup>

getPositionObject(index: number, callback: AsyncCallback&lt;FileAsset&gt;): void

Obtains a file asset with the specified index in the result set. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name      | Type                                      | Mandatory  | Description                |
| -------- | ---------------------------------------- | ---- | ------------------ |
| index    | number                                   | Yes   | Index of the file to obtain. The value starts from 0 and must be smaller than the **count** value of the result set.    |
| callback | AsyncCallback&lt;[FileAsset](#fileasset7)&gt; | Yes   | Callback used to return the last file asset.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    fetchFileResult.getPositionObject(0, (error, fileAsset) => {
        if (error) {
            console.error('getPositionObject failed with error: ' + error);
            return;
        }
        console.info('getPositionObject successfully, displayName: ' + fileAsset.displayName);
        fetchFileResult.close();
    })
}
```

### getPositionObject<sup>7+</sup>

getPositionObject(index: number): Promise&lt;FileAsset&gt;

Obtains a file asset with the specified index in the result set. This API uses a promise to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name   | Type    | Mandatory  | Description            |
| ----- | ------ | ---- | -------------- |
| index | number | Yes   | Index of the file to obtain. The value starts from 0 and must be smaller than the **count** value of the result set.|

**Return value**

| Type                                   | Description             |
| --------------------------------------- | ----------------- |
| Promise&lt;[FileAsset](#fileasset7)&gt; | Promise used to return the next file asset.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    fetchFileResult.getPositionObject(0).then((fileAsset) => {
        console.info('getPositionObject successfully, displayName: ' + fileAsset.displayName);
        fetchFileResult.close();
    }).catch((error) => {
        console.error('getPositionObject failed with error: ' + error);
    });
}
```

### getAllObject<sup>7+</sup>

getAllObject(callback: AsyncCallback&lt;Array&lt;FileAsset&gt;&gt;): void

Obtains all the file assets in the result set. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name      | Type                                      | Mandatory  | Description                  |
| -------- | ---------------------------------------- | ---- | -------------------- |
| callback | AsyncCallback&lt;Array&lt;[FileAsset](#fileasset7)&gt;&gt; | Yes   | Callback used to return the file assets.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    fetchFileResult.getAllObject((error, fileAssetList) => {
        if (error) {
           console.error('getAllObject failed with error: ' + error);
           return;
        }
        for (let i = 0; i < fetchFileResult.getCount(); i++) {
            console.info('getAllObject fileAssetList ' + i + ' displayName: ' + fileAssetList[i].displayName);
        }
        fetchFileResult.close();
    })
}
```

### getAllObject<sup>7+</sup>

getAllObject(): Promise&lt;Array&lt;FileAsset&gt;&gt;

Obtains all the file assets in the result set. This API uses a promise to return the result.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type                                    | Description                 |
| ---------------------------------------- | --------------------- |
| Promise&lt;Array&lt;[FileAsset](#fileasset7)&gt;&gt; | Promise used to return the file assets.|

**Example**

```js
async function example() {
    let fileKeyObj = mediaLibrary.FileKey;
    let imageType = mediaLibrary.MediaType.IMAGE;
    let getImageOp = {
        selections: fileKeyObj.MEDIA_TYPE + '= ?',
        selectionArgs: [imageType.toString()],
        order: fileKeyObj.DATE_ADDED + ' DESC',
    };
    let fetchFileResult = await media.getFileAssets(getImageOp);
    fetchFileResult.getAllObject().then((fileAssetList) => {
        for (let i = 0; i < fetchFileResult.getCount(); i++) {
            console.info('getAllObject fileAssetList ' + i + ' displayName: ' + fileAssetList[i].displayName);
        } 
        fetchFileResult.close();
    }).catch((error) => {
        console.error('getAllObject failed with error: ' + error);
    });
}
```

## Album<sup>7+</sup>

Provides APIs to implement a physical album.

### Attributes

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

| Name          | Type   | Readable  | Writable  | Description     |
| ------------ | ------ | ---- | ---- | ------- |
| albumId | number | Yes   | No   | Album ID.   |
| albumName | string | Yes   | Yes   | Album name.   |
| albumUri<sup>8+</sup> | string | Yes   | No   | Album URI.  |
| dateModified | number | Yes   | No   | Date when the album was modified.   |
| count<sup>8+</sup> | number | Yes   | No   | Number of files in the album.|
| relativePath<sup>8+</sup> | string | Yes   | No   | Relative path of the album.   |
| coverUri<sup>8+</sup> | string | Yes   | No   | URI of the cover file of the album.|

### commitModify<sup>8+</sup>

commitModify(callback: AsyncCallback&lt;void&gt;): void

Commits the modification in the album attributes to the database. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name  | Type                     | Mandatory| Description      |
| -------- | ------------------------- | ---- | ---------- |
| callback | AsyncCallback&lt;void&gt; | Yes  | Void callback.|

**Example**

```js
async function example() {
    let AlbumNoArgsfetchOp = {
        selections: '',
        selectionArgs: [],
    };
    const albumList = await media.getAlbums(AlbumNoArgsfetchOp);
    const album = albumList[0];
    album.albumName = 'hello';
    album.commitModify((error) => {
        if (error) {
            console.error('commitModify failed with error: ' + error);
            return;
        }
        console.info('commitModify successful.');
    })
}
```

### commitModify<sup>8+</sup>

commitModify(): Promise&lt;void&gt;

Commits the modification in the album attributes to the database. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA and ohos.permission.WRITE_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Return value**

| Type                 | Description          |
| ------------------- | ------------ |
| Promise&lt;void&gt; | Void promise.|

**Example**

```js
async function example() {
    let AlbumNoArgsfetchOp = {
        selections: '',
        selectionArgs: [],
    };
    const albumList = await media.getAlbums(AlbumNoArgsfetchOp);
    const album = albumList[0];
    album.albumName = 'hello';
    album.commitModify().then(() => {
        console.info('commitModify successfully');
    }).catch((error) => {
        console.error('commitModify failed with error: ' + error);
    });
}
```

### getFileAssets<sup>7+</sup>

getFileAssets(options: MediaFetchOptions, callback: AsyncCallback&lt;FetchFileResult&gt;): void

Obtains the file assets in this album. This API uses an asynchronous callback to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name  | Type                                               | Mandatory| Description                               |
| -------- | --------------------------------------------------- | ---- | ----------------------------------- |
| options  | [MediaFetchOptions](#mediafetchoptions7)            | Yes  | Options for fetching the files.                     |
| callback | AsyncCallback<[FetchFileResult](#fetchfileresult7)> | Yes  | Callback used to return the file assets.|

**Example**

```js
async function example() {
    let AlbumNoArgsfetchOp = {
        selections: '',
        selectionArgs: [],
    };
    let fileNoArgsfetchOp = {
        selections: '',
        selectionArgs: [],
    }
    // Obtain the albums that meet the retrieval options and return the album list.
    const albumList = await media.getAlbums(AlbumNoArgsfetchOp);
    const album = albumList[0];
    // Obtain an album from the album list and obtain all media assets that meet the retrieval options in the album.
    album.getFileAssets(fileNoArgsfetchOp, (error, fetchFileResult) => {
        if (error) {
            console.error('album getFileAssets failed with error: ' + error);
            return;
        }
        let count = fetchFileResult.getCount();
        console.info('album getFileAssets successfully, count: ' + count);
        fetchFileResult.close();
    });
}
```

### getFileAssets<sup>7+</sup>

 getFileAssets(options?: MediaFetchOptions): Promise&lt;FetchFileResult&gt;

Obtains the file assets in this album. This API uses a promise to return the result.

**Required permissions**: ohos.permission.READ_MEDIA

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

**Parameters**

| Name | Type                                    | Mandatory| Description          |
| ------- | ---------------------------------------- | ---- | -------------- |
| options | [MediaFetchOptions](#mediafetchoptions7) | No  | Options for fetching the files.|

**Return value**

| Type                                         | Description                     |
| --------------------------------------------- | ------------------------- |
| Promise<[FetchFileResult](#fetchfileresult7)> | Promise used to return the file assets.|

**Example**

```js
async function example() {
    let AlbumNoArgsfetchOp = {
        selections: '',
        selectionArgs: [],
    };
    let fileNoArgsfetchOp = {
        selections: '',
        selectionArgs: [],
    };
    // Obtain the albums that meet the retrieval options and return the album list.
    const albumList = await media.getAlbums(AlbumNoArgsfetchOp);
    const album = albumList[0];
    // Obtain an album from the album list and obtain all media assets that meet the retrieval options in the album.
    album.getFileAssets(fileNoArgsfetchOp).then((fetchFileResult) => {
        let count = fetchFileResult.getCount();
        console.info('album getFileAssets successfully, count: ' + count);
        fetchFileResult.close();
    }).catch((error) => {
        console.error('album getFileAssets failed with error: ' + error);
    });
}
```

## PeerInfo<sup>8+</sup>

Describes information about a registered device.

**System API**: This is a system API.

**System capability**: SystemCapability.Multimedia.MediaLibrary.DistributedCore

| Name      | Type                      | Readable| Writable| Description            |
| ---------- | -------------------------- | ---- | ---- | ---------------- |
| deviceName | string                     | Yes  | No  | Name of the registered device.  |
| networkId  | string                     | Yes  | No  | Network ID of the registered device.|
| deviceType | [DeviceType](#devicetype8) | Yes  | No  | Type of the registered device.        |
| isOnline   | boolean                    | Yes  | No  | Whether the registered device is online.        |



## MediaType<sup>8+</sup>

Enumerates media types.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

| Name |  Value|  Description|
| ----- |  ---- | ---- |
| FILE  |  0 | File.|
| IMAGE |  1 | Image.|
| VIDEO |  2 | Video.|
| AUDIO |  3 | Audio.|

## FileKey<sup>8+</sup>

Enumerates key file information.

> **NOTE**
> The **bucket_id** field may change after file rename or movement. Therefore, you must obtain the field again before using it.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

| Name         | Value             | Description                                                      |
| ------------- | ------------------- | ---------------------------------------------------------- |
| ID            | 'file_id'             | File ID.                                                  |
| RELATIVE_PATH | 'relative_path'       | Relative public directory of the file.                                          |
| DISPLAY_NAME  | 'display_name'        | Display file name.                                                  |
| PARENT        | 'parent'              | Parent directory ID.                                                  |
| MIME_TYPE     | 'mime_type'           | Extended file attributes, such as image/, video/, and file/*.                                            |
| MEDIA_TYPE    | 'media_type'          | Media type.                                                  |
| SIZE          | 'size'                | File size, in bytes.                                    |
| DATE_ADDED    | 'date_added'          | Date when the file was added. The value is the number of seconds elapsed since the Epoch time.            |
| DATE_MODIFIED | 'date_modified'       | Date when the file content (not the file name) was last modified. The value is the number of seconds elapsed since the Epoch time.|
| DATE_TAKEN    | 'date_taken'          | Date when the file (photo) was taken. The value is the number of seconds elapsed since the Epoch time.            |
| TITLE         | 'title'               | Title in the file.                                                  |
| ARTIST        | 'artist'              | Artist of the file.                                                      |
| AUDIOALBUM    | 'audio_album'         | Audio album.                                                      |
| DURATION      | 'duration'            | Duration, in ms.                                      |
| WIDTH         | 'width'               | Image width, in pixels.                                    |
| HEIGHT        | 'height'              | Image height, in pixels.                                    |
| ORIENTATION   | 'orientation'         | Image display direction (clockwise rotation angle, for example, 0, 90, and 180, in degrees).|
| ALBUM_ID      | 'bucket_id'           | ID of the album to which the file belongs.                                      |
| ALBUM_NAME    | 'bucket_display_name' | Name of the album to which the file belongs.                                        |

## DirectoryType<sup>8+</sup>

Enumerates directory types.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

| Name         | Value|  Description              |
| ------------- | --- | ------------------ |
| DIR_CAMERA    |  0 | Directory of camera files.|
| DIR_VIDEO     |  1 |  Directory of video files.      |
| DIR_IMAGE     |  2 | Directory of image files.      |
| DIR_AUDIO     |  3 | Directory of audio files.      |
| DIR_DOCUMENTS |  4 | Directory of documents.      |
| DIR_DOWNLOAD  |  5 |  Download directory.      |

## DeviceType<sup>8+</sup>

Enumerates device types.

**System API**: This is a system API.

**System capability**: SystemCapability.Multimedia.MediaLibrary.DistributedCore

| Name        |  Value| Description      |
| ------------ | --- | ---------- |
| TYPE_UNKNOWN |  0 | Unknown.|
| TYPE_LAPTOP  |  1 | Laptop.|
| TYPE_PHONE   |  2 | Phone.      |
| TYPE_TABLET  |  3 | Tablet.  |
| TYPE_WATCH   |  4 | Smart watch.  |
| TYPE_CAR     |  5 | Vehicle-mounted device.  |
| TYPE_TV      |  6 | TV.  |

## MediaFetchOptions<sup>7+</sup>

Describes options for fetching media files.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

| Name                   | Type               | Readable| Writable| Description                                                        |
| ----------------------- | ------------------- | ---- | ---- | ------------------------------------------------------------ |
| selections              | string              | Yes  | Yes  | Conditions for fetching files. The enumerated values in [FileKey](#filekey8) are used as the column names of the conditions. Example:<br>selections: mediaLibrary.FileKey.MEDIA_TYPE + '= ? OR ' + mediaLibrary.FileKey.MEDIA_TYPE + '= ?', |
| selectionArgs           | Array&lt;string&gt; | Yes  | Yes  | Value of the condition, which corresponds to the value of the condition column in **selections**.<br>Example:<br>selectionArgs: [mediaLibrary.MediaType.IMAGE.toString(), mediaLibrary.MediaType.VIDEO.toString()], |
| order                   | string              | Yes  | Yes  | Sorting mode of the search results, which can be ascending or descending. The enumerated values in [FileKey](#filekey8) are used as the columns for sorting the search results. Example:<br>Ascending: order: mediaLibrary.FileKey.DATE_ADDED + ' ASC'<br>Descending: order: mediaLibrary.FileKey.DATE_ADDED + ' DESC'|
| uri<sup>8+</sup>        | string              | Yes  | Yes  | File URI.                                                     |
| networkId<sup>8+</sup>  | string              | Yes  | Yes  | Network ID of the registered device.                                              |
| extendArgs<sup>8+</sup> | string              | Yes  | Yes  | Extended parameters for fetching the files. Currently, no extended parameters are available.                        |

## Size<sup>8+</sup>

Describes the image size.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

| Name    | Type    | Readable  | Writable  | Description      |
| ------ | ------ | ---- | ---- | -------- |
| width  | number | Yes   | Yes   | Image width, in pixels.|
| height | number | Yes   | Yes   | Image height, in pixels.|

## MediaAssetOption

Implements the media asset option.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core


| Name        | Type  | Readable| Writable| Description                                                        |
| ------------ | ------ | ---- | ---- | ------------------------------------------------------------ |
| src          | string | Yes  | Yes  | Application sandbox oath of the local file.                                      |
| mimeType     | string | Yes  | Yes  | Multipurpose Internet Mail Extensions (MIME) type of the media.<br>The value can be 'image/\*', 'video/\*', 'audio/\*' or 'file\*'.|
| relativePath | string | Yes  | Yes  | Custom path for storing media assets, for example, 'Pictures/'. If this parameter is unspecified, media assets are stored in the default path.<br> Default path of images: 'Pictures/'<br> Default path of videos: 'Videos/'<br> Default path of audios: 'Audios/'<br> Default path of files: 'Documents/'|

## MediaSelectOption

Describes media selection option.

**System capability**: SystemCapability.Multimedia.MediaLibrary.Core

| Name   | Type    | Readable| Writable| Description                  |
| ----- | ------ | ---- | ---- | -------------------- |
| type  | 'image' &#124; 'video' &#124; 'media' | Yes   | Yes | Media type, which can be **image**, **media**, or **video**. Currently, only **media** is supported.|
| count | number | Yes   | Yes | Maximum number of media assets that can be selected. The value starts from 1, which indicates that one media asset can be selected.           |