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!9982 【翻译完成】#I5OTIF 

Merge pull request !9982 from Annie_wang/PR8877A
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en/application-dev/database/database-storage-guidelines.md
浏览文件 @ 8a3728ab
...@@ -90,9 +90,9 @@ Use the following APIs to delete a **Storage** instance or data file. ...@@ -90,9 +90,9 @@ Use the following APIs to delete a **Storage** instance or data file.
context.getFilesDir().then((filePath) => { context.getFilesDir().then((filePath) => {
path = filePath; path = filePath;
console.info("======================>getFilesDirPromsie====================>"); console.info("======================>getFilesDirPromsie====================>");
});
let promise = dataStorage.getStorage(path + '/mystore'); let promise = dataStorage.getStorage(path + '/mystore');
});
``` ```
...@@ -120,14 +120,15 @@ Use the following APIs to delete a **Storage** instance or data file. ...@@ -120,14 +120,15 @@ Use the following APIs to delete a **Storage** instance or data file.
```js ```js
promise.then((storage) => { promise.then((storage) => {
let getPromise = storage.get('startup', 'default'); let getPromise = storage.get('startup', 'default')
getPromise.then((value) => { getPromise.then((value) => {
console.info("The value of startup is " + value); console.info("The value of startup is " + value);
}).catch((err) => { }).catch((err) => {
console.info("Failed to get the value of startup with err: " + err); console.info("Failed to get the value of startup with err: " + err);
}) })
}).catch((err) => { }).catch((err) => {
console.info("Failed to get the storage."); console.info("Failed to get the storage.")
}) })
``` ```
...@@ -149,7 +150,7 @@ Use the following APIs to delete a **Storage** instance or data file. ...@@ -149,7 +150,7 @@ Use the following APIs to delete a **Storage** instance or data file.
var observer = function (key) { var observer = function (key) {
console.info("The key of " + key + " changed."); console.info("The key of " + key + " changed.");
} }
storage.on('change', observer); storage.on('change', observer)
storage.putSync('startup', 'auto'); // Modify data in the Storage instance. storage.putSync('startup', 'auto'); // Modify data in the Storage instance.
storage.flushSync(); // Trigger the StorageObserver callback. storage.flushSync(); // Trigger the StorageObserver callback.
...@@ -169,7 +170,7 @@ Use the following APIs to delete a **Storage** instance or data file. ...@@ -169,7 +170,7 @@ Use the following APIs to delete a **Storage** instance or data file.
promise.then(() => { promise.then(() => {
console.info("Succeeded in deleting the storage."); console.info("Succeeded in deleting the storage.");
}).catch((err) => { }).catch((err) => {
console.info("Failed to deleted the storage with err: " + err); console.info("Failed to delete the storage with err: " + err);
}) })
``` ```
en/application-dev/reference/apis/js-apis-data-storage.md
浏览文件 @ 8a3728ab
...@@ -3,10 +3,13 @@ ...@@ -3,10 +3,13 @@
Lightweight storage provides applications with data processing capability and allows applications to perform lightweight data storage and query. Data is stored in key-value (KV) pairs. Keys are of the string type, and values can be of the number, string, or Boolean type. Lightweight storage provides applications with data processing capability and allows applications to perform lightweight data storage and query. Data is stored in key-value (KV) pairs. Keys are of the string type, and values can be of the number, string, or Boolean type.
> **NOTE** > **NOTE**<br/>
> >
> The initial APIs of this module are supported since API version 6. Newly added APIs will be marked with a superscript to indicate their earliest API version. > - The initial APIs of this module are supported since API version 6. Newly added APIs will be marked with a superscript to indicate their earliest API version.
>
> - The APIs of this module are no longer maintained since API Version 9. You are advised to use [`@ohos.data.preferences`](js-apis-data-preferences.md).
>
> - The APIs of this module can be used only in the FA model.
## Modules to Import ## Modules to Import
...@@ -35,15 +38,15 @@ Reads the specified file and loads its data to the **Storage** instance for data ...@@ -35,15 +38,15 @@ Reads the specified file and loads its data to the **Storage** instance for data
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name| Type | Mandatory| Description |
| ---- | ------ | --------- | ------------------------ | | ------ | ------ | ---- | -------------------------- |
| path | string | Yes | Path of the target file. | | path | string | Yes | Path of the target file.|
**Return value** **Return value**
| Type | Description | | Type | Description |
| ------------------- | ------------------------------------------------------ | | ------------------- | ------------------------------------------------- |
| [Storage](#storage) | **Storage** instance used for data storage operations. | | [Storage](#storage) | **Storage** instance used for data storage operations.|
**Example** **Example**
...@@ -55,11 +58,11 @@ var context = featureAbility.getContext(); ...@@ -55,11 +58,11 @@ var context = featureAbility.getContext();
context.getFilesDir().then((filePath) => { context.getFilesDir().then((filePath) => {
path = filePath; path = filePath;
console.info("======================>getFilesDirPromise====================>"); console.info("======================>getFilesDirPromise====================>");
});
let storage = data_storage.getStorageSync(path + '/mystore'); let storage = data_storage.getStorageSync(path + '/mystore');
storage.putSync('startup', 'auto'); storage.putSync('startup', 'auto');
storage.flushSync(); storage.flushSync();
});
``` ```
...@@ -73,9 +76,9 @@ Reads the specified file and loads its data to the **Storage** instance for data ...@@ -73,9 +76,9 @@ Reads the specified file and loads its data to the **Storage** instance for data
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name | Type | Mandatory| Description |
| -------- | ---------------------------------------- | --------- | --------------------------------------------- | | -------- | ---------------------------------------- | ---- | -------------------------- |
| path | string | Yes | Path of the target file. | | path | string | Yes | Path of the target file.|
| callback | AsyncCallback&lt;[Storage](#storage)&gt; | Yes | Callback used to return the execution result. | | callback | AsyncCallback&lt;[Storage](#storage)&gt; | Yes | Callback used to return the execution result. |
**Example** **Example**
...@@ -88,16 +91,16 @@ var context = featureAbility.getContext(); ...@@ -88,16 +91,16 @@ var context = featureAbility.getContext();
context.getFilesDir().then((filePath) => { context.getFilesDir().then((filePath) => {
path = filePath; path = filePath;
console.info("======================>getFilesDirPromise====================>"); console.info("======================>getFilesDirPromise====================>");
});
data_storage.getStorage(path + '/mystore', function (err, storage) { data_storage.getStorage(path + '/mystore', function (err, storage) {
if (err) { if (err) {
console.info("Failed to get the storage. path: " + path + '/mystore'); console.info("Failed to get the storage. path: " + path + '/mystore');
return; return;
} }
storage.putSync('startup', 'auto'); storage.putSync('startup', 'auto');
storage.flushSync(); storage.flushSync();
}) })
});
``` ```
...@@ -111,15 +114,15 @@ Reads the specified file and loads its data to the **Storage** instance for data ...@@ -111,15 +114,15 @@ Reads the specified file and loads its data to the **Storage** instance for data
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name| Type | Mandatory| Description |
| ---- | ------ | --------- | ------------------------ | | ------ | ------ | ---- | -------------------------- |
| path | string | Yes | Path of the target file. | | path | string | Yes | Path of the target file.|
**Return value** **Return value**
| Type | Description | | Type | Description |
| ---------------------------------- | ---------------------------------- | | ---------------------------------- | ------------------------------- |
| Promise&lt;[Storage](#storage)&gt; | Promise used to return the result. | | Promise&lt;[Storage](#storage)&gt; | Promise used to return the result.|
**Example** **Example**
...@@ -131,15 +134,15 @@ var context = featureAbility.getContext(); ...@@ -131,15 +134,15 @@ var context = featureAbility.getContext();
context.getFilesDir().then((filePath) => { context.getFilesDir().then((filePath) => {
path = filePath; path = filePath;
console.info("======================>getFilesDirPromise====================>"); console.info("======================>getFilesDirPromise====================>");
});
let getPromise = data_storage.getStorage(path + '/mystore'); let getPromise = data_storage.getStorage(path + '/mystore');
getPromise.then((storage) => { getPromise.then((storage) => {
storage.putSync('startup', 'auto'); storage.putSync('startup', 'auto');
storage.flushSync(); storage.flushSync();
}).catch((err) => { }).catch((err) => {
console.info("Failed to get the storage. path: " + path + '/mystore'); console.info("Failed to get the storage. path: " + path + '/mystore');
}) })
});
``` ```
...@@ -153,9 +156,9 @@ Deletes the singleton **Storage** instance of a file from the memory, and delete ...@@ -153,9 +156,9 @@ Deletes the singleton **Storage** instance of a file from the memory, and delete
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name| Type | Mandatory| Description |
| ---- | ------ | --------- | ------------------------ | | ------ | ------ | ---- | -------------------------- |
| path | string | Yes | Path of the target file. | | path | string | Yes | Path of the target file.|
**Example** **Example**
...@@ -167,12 +170,11 @@ var context = featureAbility.getContext(); ...@@ -167,12 +170,11 @@ var context = featureAbility.getContext();
context.getFilesDir().then((filePath) => { context.getFilesDir().then((filePath) => {
path = filePath; path = filePath;
console.info("======================>getFilesDirPromise====================>"); console.info("======================>getFilesDirPromise====================>");
});
data_storage.deleteStorageSync(path + '/mystore'); data_storage.deleteStorageSync(path + '/mystore');
});
``` ```
## data_storage.deleteStorage ## data_storage.deleteStorage
deleteStorage(path: string, callback: AsyncCallback&lt;void&gt;): void deleteStorage(path: string, callback: AsyncCallback&lt;void&gt;): void
...@@ -183,9 +185,9 @@ Deletes the singleton **Storage** instance of a file from the memory, and delete ...@@ -183,9 +185,9 @@ Deletes the singleton **Storage** instance of a file from the memory, and delete
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name | Type | Mandatory| Description |
| -------- | ------------------------- | --------- | ------------------------------- | | -------- | ------------------------- | ---- | -------------------------- |
| path | string | Yes | Path of the target file. | | path | string | Yes | Path of the target file.|
| callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. | | callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. |
**Example** **Example**
...@@ -198,15 +200,15 @@ var context = featureAbility.getContext(); ...@@ -198,15 +200,15 @@ var context = featureAbility.getContext();
context.getFilesDir().then((filePath) => { context.getFilesDir().then((filePath) => {
path = filePath; path = filePath;
console.info("======================>getFilesDirPromise====================>"); console.info("======================>getFilesDirPromise====================>");
});
data_storage.deleteStorage(path + '/mystore', function (err) { data_storage.deleteStorage(path + '/mystore', function (err) {
if (err) { if (err) {
console.info("Failed to delete the storage with err: " + err); console.info("Failed to delete the storage with err: " + err);
return; return;
} }
console.info("Succeeded in deleting the storage."); console.info("Succeeded in deleting the storage.");
}) })
});
``` ```
...@@ -220,13 +222,14 @@ Deletes the singleton **Storage** instance of a file from the memory, and delete ...@@ -220,13 +222,14 @@ Deletes the singleton **Storage** instance of a file from the memory, and delete
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name| Type | Mandatory| Description |
| ---- | ------ | --------- | ------------------------ | | ------ | ------ | ---- | -------------------------- |
| path | string | Yes | Path of the target file. | | path | string | Yes | Path of the target file.|
**Return value** **Return value**
| Type | Description | | Type | Description |
| ------------------- | ------------------------------ | | ------------------- | ------------------------------- |
| Promise&lt;void&gt; | Promise that returns no value. | | Promise&lt;void&gt; | Promise that returns no value. |
**Example** **Example**
...@@ -239,14 +242,14 @@ var context = featureAbility.getContext(); ...@@ -239,14 +242,14 @@ var context = featureAbility.getContext();
context.getFilesDir().then((filePath) => { context.getFilesDir().then((filePath) => {
path = filePath; path = filePath;
console.info("======================>getFilesDirPromise====================>"); console.info("======================>getFilesDirPromise====================>");
});
let promisedelSt = data_storage.deleteStorage(path + '/mystore'); let promisedelSt = data_storage.deleteStorage(path + '/mystore');
promisedelSt.then(() => { promisedelSt.then(() => {
console.info("Succeeded in deleting the storage."); console.info("Succeeded in deleting the storage.");
}).catch((err) => { }).catch((err) => {
console.info("Failed to delete the storage with err: " + err); console.info("Failed to delete the storage with err: " + err);
}) })
});
``` ```
...@@ -259,10 +262,9 @@ Removes the singleton **Storage** instance of a file from the cache. The removed ...@@ -259,10 +262,9 @@ Removes the singleton **Storage** instance of a file from the cache. The removed
**System capability**: SystemCapability.DistributedDataManager.Preferences.Core **System capability**: SystemCapability.DistributedDataManager.Preferences.Core
**Parameters** **Parameters**
| Name| Type | Mandatory| Description |
| Name | Type | Mandatory | Description | | ------ | ------ | ---- | -------------------------- |
| ---- | ------ | --------- | ------------------------ | | path | string | Yes | Path of the target file.|
| path | string | Yes | Path of the target file. |
**Example** **Example**
...@@ -274,9 +276,9 @@ var context = featureAbility.getContext(); ...@@ -274,9 +276,9 @@ var context = featureAbility.getContext();
context.getFilesDir().then((filePath) => { context.getFilesDir().then((filePath) => {
path = filePath; path = filePath;
console.info("======================>getFilesDirPromise====================>"); console.info("======================>getFilesDirPromise====================>");
});
data_storage.removeStorageFromCacheSync(path + '/mystore'); data_storage.removeStorageFromCacheSync(path + '/mystore');
});
``` ```
...@@ -290,9 +292,9 @@ Removes the singleton **Storage** instance of a file from the cache. The removed ...@@ -290,9 +292,9 @@ Removes the singleton **Storage** instance of a file from the cache. The removed
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name | Type | Mandatory| Description |
| -------- | ------------------------- | --------- | ------------------------------- | | -------- | ------------------------- | ---- | -------------------------- |
| path | string | Yes | Path of the target file. | | path | string | Yes | Path of the target file.|
| callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. | | callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. |
**Example** **Example**
...@@ -305,15 +307,15 @@ var context = featureAbility.getContext(); ...@@ -305,15 +307,15 @@ var context = featureAbility.getContext();
context.getFilesDir().then((filePath) => { context.getFilesDir().then((filePath) => {
path = filePath; path = filePath;
console.info("======================>getFilesDirPromise====================>"); console.info("======================>getFilesDirPromise====================>");
});
data_storage.removeStorageFromCache(path + '/mystore', function (err) { data_storage.removeStorageFromCache(path + '/mystore', function (err) {
if (err) { if (err) {
console.info("Failed to remove storage from cache with err: " + err); console.info("Failed to remove storage from cache with err: " + err);
return; return;
} }
console.info("Succeeded in removing storage from cache."); console.info("Succeeded in removing storage from cache.");
}) })
});
``` ```
...@@ -327,14 +329,14 @@ Removes the singleton **Storage** instance of a file from the cache. The removed ...@@ -327,14 +329,14 @@ Removes the singleton **Storage** instance of a file from the cache. The removed
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name| Type | Mandatory| Description |
| ---- | ------ | --------- | ------------------------ | | ------ | ------ | ---- | -------------------------- |
| path | string | Yes | Path of the target file. | | path | string | Yes | Path of the target file.|
**Return value** **Return value**
| Type | Description | | Type | Description |
| ------------------- | ------------------------------ | | ------------------- | ------------------------------- |
| Promise&lt;void&gt; | Promise that returns no value. | | Promise&lt;void&gt; | Promise that returns no value. |
**Example** **Example**
...@@ -347,22 +349,20 @@ var context = featureAbility.getContext(); ...@@ -347,22 +349,20 @@ var context = featureAbility.getContext();
context.getFilesDir().then((filePath) => { context.getFilesDir().then((filePath) => {
path = filePath; path = filePath;
console.info("======================>getFilesDirPromise====================>"); console.info("======================>getFilesDirPromise====================>");
});
let promiserevSt = data_storage.removeStorageFromCache(path + '/mystore') let promiserevSt = data_storage.removeStorageFromCache(path + '/mystore')
promiserevSt.then(() => { promiserevSt.then(() => {
console.info("Succeeded in removing storage from cache."); console.info("Succeeded in removing storage from cache.");
}).catch((err) => { }).catch((err) => {
console.info("Failed to remove storage from cache with err: " + err); console.info("Failed to remove storage from cache with err: " + err);
}) })
});
``` ```
## Storage ## Storage
Provides APIs for obtaining and modifying storage data. Provides APIs for obtaining and modifying storage data.
### getSync ### getSync
getSync(key: string, defValue: ValueType): ValueType getSync(key: string, defValue: ValueType): ValueType
...@@ -373,16 +373,16 @@ Obtains the value corresponding to a key. If the value is null or not in the def ...@@ -373,16 +373,16 @@ Obtains the value corresponding to a key. If the value is null or not in the def
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name | Type | Mandatory| Description |
| -------- | ----------------------- | --------- | ------------------------------------------------------------ | | -------- | ----------------------- | ---- | ------------------------------------------------------------ |
| key | string | Yes | Key of the data. It cannot be empty. | | key | string | Yes | Key of the data. It cannot be empty. |
| defValue | [ValueType](#valuetype) | Yes | Default value to be returned if the value of the specified key does not exist. It can be a number, string, or Boolean value. | | defValue | [ValueType](#valuetype) | Yes | Default value to be returned if the value of the specified key does not exist. It can be a number, string, or Boolean value.|
**Return value** **Return value**
| Type | Description | | Type | Description |
| --------- | ------------------------------------------------------------ | | --------- | -------------------------------------------------------- |
| ValueType | Value corresponding to the specified key. If the value is null or not in the default value format, the default value is returned. | | ValueType | Value corresponding to the specified key. If the value is null or not in the default value format, the default value is returned.|
**Example** **Example**
...@@ -402,10 +402,10 @@ Obtains the value corresponding to a key. If the value is null or not in the def ...@@ -402,10 +402,10 @@ Obtains the value corresponding to a key. If the value is null or not in the def
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name | Type | Mandatory| Description |
| -------- | ------------------------------ | --------- | ------------------------------------------------------------ | | -------- | ------------------------------ | ---- | ----------------------------------------- |
| key | string | Yes | Key of the data. It cannot be empty. | | key | string | Yes | Key of the data. It cannot be empty. |
| defValue | [ValueType](#valuetype) | Yes | Default value to be returned. It can be a number, string, or Boolean value. | | defValue | [ValueType](#valuetype) | Yes | Default value to be returned. It can be a number, string, or Boolean value.|
| callback | AsyncCallback&lt;ValueType&gt; | Yes | Callback used to return the execution result. | | callback | AsyncCallback&lt;ValueType&gt; | Yes | Callback used to return the execution result. |
**Example** **Example**
...@@ -431,18 +431,19 @@ Obtains the value corresponding to a key. If the value is null or not in the def ...@@ -431,18 +431,19 @@ Obtains the value corresponding to a key. If the value is null or not in the def
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name | Type | Mandatory| Description |
| -------- | ----------------------- | --------- | ------------------------------------------------------------ | | -------- | ----------------------- | ---- | ----------------------------------------- |
| key | string | Yes | Key of the data. It cannot be empty. | | key | string | Yes | Key of the data. It cannot be empty. |
| defValue | [ValueType](#valuetype) | Yes | Default value to be returned. It can be a number, string, or Boolean value. | | defValue | [ValueType](#valuetype) | Yes | Default value to be returned. It can be a number, string, or Boolean value.|
**Return value** **Return value**
| Type | Description | | Type | Description |
| ------------------------ | ---------------------------------- | | ------------------------ | ------------------------------- |
| Promise&lt;ValueType&gt; | Promise used to return the result. | | Promise&lt;ValueType&gt; | Promise used to return the result.|
**Example** **Example**
```js ```js
let promiseget = storage.get('startup', 'default'); let promiseget = storage.get('startup', 'default');
promiseget.then((value) => { promiseget.then((value) => {
...@@ -463,15 +464,15 @@ Obtains the **Storage** instance corresponding to the specified file, writes dat ...@@ -463,15 +464,15 @@ Obtains the **Storage** instance corresponding to the specified file, writes dat
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name| Type | Mandatory| Description |
| ----- | ----------------------- | --------- | ------------------------------------------------------------ | | ------ | ----------------------- | ---- | ----------------------------------------- |
| key | string | Yes | Key of the data. It cannot be empty. | | key | string | Yes | Key of the data. It cannot be empty. |
| value | [ValueType](#valuetype) | Yes | New value to store. It can be a number, string, or Boolean value. | | value | [ValueType](#valuetype) | Yes | New value to store. It can be a number, string, or Boolean value.|
**Example** **Example**
```js ```js
storage.putSync('startup', 'auto') storage.putSync('startup', 'auto');
``` ```
...@@ -485,10 +486,10 @@ Obtains the **Storage** instance corresponding to the specified file, writes dat ...@@ -485,10 +486,10 @@ Obtains the **Storage** instance corresponding to the specified file, writes dat
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name | Type | Mandatory| Description |
| -------- | ------------------------- | --------- | ------------------------------------------------------------ | | -------- | ------------------------- | ---- | ----------------------------------------- |
| key | string | Yes | Key of the data. It cannot be empty. | | key | string | Yes | Key of the data. It cannot be empty. |
| value | [ValueType](#valuetype) | Yes | New value to store. It can be a number, string, or Boolean value. | | value | [ValueType](#valuetype) | Yes | New value to store. It can be a number, string, or Boolean value.|
| callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. | | callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. |
**Example** **Example**
...@@ -514,18 +515,19 @@ Obtains the **Storage** instance corresponding to the specified file, writes dat ...@@ -514,18 +515,19 @@ Obtains the **Storage** instance corresponding to the specified file, writes dat
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name| Type | Mandatory| Description |
| ----- | ----------------------- | --------- | ------------------------------------------------------------ | | ------ | ----------------------- | ---- | ----------------------------------------- |
| key | string | Yes | Key of the data. It cannot be empty. | | key | string | Yes | Key of the data. It cannot be empty. |
| value | [ValueType](#valuetype) | Yes | New value to store. It can be a number, string, or Boolean value. | | value | [ValueType](#valuetype) | Yes | New value to store. It can be a number, string, or Boolean value.|
**Return value** **Return value**
| Type | Description | | Type | Description |
| ------------------- | ------------------------------ | | ------------------- | --------------------------- |
| Promise&lt;void&gt; | Promise that returns no value. | | Promise&lt;void&gt; | Promise that returns no value. |
**Example** **Example**
```js ```js
let promiseput = storage.put('startup', 'auto'); let promiseput = storage.put('startup', 'auto');
promiseput.then(() => { promiseput.then(() => {
...@@ -546,15 +548,15 @@ Checks whether the storage object contains data with a given key. ...@@ -546,15 +548,15 @@ Checks whether the storage object contains data with a given key.
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name| Type | Mandatory| Description |
| ---- | ------ | --------- | ------------------------------------ | | ------ | ------ | ---- | ------------------------------- |
| key | string | Yes | Key of the data. It cannot be empty. | | key | string | Yes | Key of the data. It cannot be empty.|
**Return value** **Return value**
| Type | Description | | Type | Description |
| ------- | ------------------------------------------------------------ | | ------- | ------------------------------------- |
| boolean | Returns **true** if the storage object contains data with the specified key; returns **false** otherwise. | | boolean | Returns **true** if the storage object contains data with the specified key; returns **false** otherwise.|
**Example** **Example**
...@@ -576,16 +578,16 @@ Checks whether the storage object contains data with a given key. This API uses ...@@ -576,16 +578,16 @@ Checks whether the storage object contains data with a given key. This API uses
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name | Type | Mandatory| Description |
| -------- | ---------------------------- | --------- | --------------------------------------------- | | -------- | ---------------------------- | ---- | ------------------------------- |
| key | string | Yes | Key of the data. It cannot be empty. | | key | string | Yes | Key of the data. It cannot be empty.|
| callback | AsyncCallback&lt;boolean&gt; | Yes | Callback used to return the execution result. | | callback | AsyncCallback&lt;boolean&gt; | Yes | Callback used to return the execution result. |
**Return value** **Return value**
| Type | Description | | Type | Description |
| ------- | ------------------------------------------------------------ | | ------- | ------------------------------- |
| boolean | Returns **true** if the storage object contains data with the specified key; returns **false** otherwise. | | boolean | Returns **true** if the storage object contains data with the specified key; returns **false** otherwise.|
**Example** **Example**
...@@ -612,15 +614,15 @@ Checks whether the storage object contains data with a given key. This API uses ...@@ -612,15 +614,15 @@ Checks whether the storage object contains data with a given key. This API uses
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name| Type | Mandatory| Description |
| ---- | ------ | --------- | ------------------------------------ | | ------ | ------ | ---- | ------------------------------- |
| key | string | Yes | Key of the data. It cannot be empty. | | key | string | Yes | Key of the data. It cannot be empty.|
**Return value** **Return value**
| Type | Description | | Type | Description |
| ---------------------- | ---------------------------------- | | ---------------------- | --------------------------- |
| Promise&lt;boolean&gt; | Promise used to return the result. | | Promise&lt;boolean&gt; | Promise used to return the result.|
**Example** **Example**
...@@ -646,14 +648,14 @@ Deletes data with the specified key from this storage object. ...@@ -646,14 +648,14 @@ Deletes data with the specified key from this storage object.
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name| Type | Mandatory| Description |
| ---- | ------ | --------- | ------------------------------------ | | ------ | ------ | ---- | --------------------------------- |
| key | string | Yes | Key of the data. It cannot be empty. | | key | string | Yes | Key of the data. It cannot be empty.|
**Example** **Example**
```js ```js
storage.deleteSync('startup') storage.deleteSync('startup');
``` ```
...@@ -667,9 +669,9 @@ Deletes data with the specified key from this storage object. This API uses an a ...@@ -667,9 +669,9 @@ Deletes data with the specified key from this storage object. This API uses an a
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name | Type | Mandatory| Description |
| -------- | ------------------------- | --------- | ------------------------------------ | | -------- | ------------------------- | ---- | ------------------------------- |
| key | string | Yes | Key of the data. It cannot be empty. | | key | string | Yes | Key of the data. It cannot be empty.|
| callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. | | callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. |
**Example** **Example**
...@@ -695,14 +697,14 @@ Deletes data with the specified key from this storage object. This API uses a pr ...@@ -695,14 +697,14 @@ Deletes data with the specified key from this storage object. This API uses a pr
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name| Type | Mandatory| Description |
| ---- | ------ | --------- | ---------------- | | ------ | ------ | ---- | --------------------- |
| key | string | Yes | Key of the data. | | key | string | Yes | Key of the data.|
**Return value** **Return value**
| Type | Description | | Type | Description |
| ------------------- | ------------------------------ | | ------------------- | --------------------------- |
| Promise&lt;void&gt; | Promise that returns no value. | | Promise&lt;void&gt; | Promise that returns no value. |
**Example** **Example**
...@@ -728,7 +730,7 @@ Saves the modification of this object to the **Storage** instance and synchroniz ...@@ -728,7 +730,7 @@ Saves the modification of this object to the **Storage** instance and synchroniz
**Example** **Example**
```js ```js
storage.flushSync() storage.flushSync();
``` ```
...@@ -742,8 +744,8 @@ Saves the modification of this object to the **Storage** instance and synchroniz ...@@ -742,8 +744,8 @@ Saves the modification of this object to the **Storage** instance and synchroniz
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name | Type | Mandatory| Description |
| -------- | ------------------------- | --------- | ------------------------------- | | -------- | ------------------------- | ---- | ---------- |
| callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. | | callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. |
**Example** **Example**
...@@ -770,7 +772,7 @@ Saves the modification of this object to the **Storage** instance and synchroniz ...@@ -770,7 +772,7 @@ Saves the modification of this object to the **Storage** instance and synchroniz
**Return value** **Return value**
| Type | Description | | Type | Description |
| ------------------- | ------------------------------ | | ------------------- | --------------------------- |
| Promise&lt;void&gt; | Promise that returns no value. | | Promise&lt;void&gt; | Promise that returns no value. |
**Example** **Example**
...@@ -796,7 +798,7 @@ Clears this **Storage** object. ...@@ -796,7 +798,7 @@ Clears this **Storage** object.
**Example** **Example**
```js ```js
storage.clearSync() storage.clearSync();
``` ```
...@@ -810,8 +812,8 @@ Clears this **Storage** object. This API uses an asynchronous callback to return ...@@ -810,8 +812,8 @@ Clears this **Storage** object. This API uses an asynchronous callback to return
**Parameters** **Parameters**
| Name | Type | Mandatory | Description | | Name | Type | Mandatory| Description |
| -------- | ------------------------- | --------- | ------------------------------- | | -------- | ------------------------- | ---- | ---------- |
| callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. | | callback | AsyncCallback&lt;void&gt; | Yes | Callback that returns no value. |
**Example** **Example**
...@@ -836,9 +838,8 @@ Clears this **Storage** object. This API uses a promise to return the result. ...@@ -836,9 +838,8 @@ Clears this **Storage** object. This API uses a promise to return the result.
**System capability**: SystemCapability.DistributedDataManager.Preferences.Core **System capability**: SystemCapability.DistributedDataManager.Preferences.Core
**Return value** **Return value**
| Type | Description | | Type | Description |
| ------------------- | ------------------------------ | | ------------------- | --------------------------- |
| Promise&lt;void&gt; | Promise that returns no value. | | Promise&lt;void&gt; | Promise that returns no value. |
**Example** **Example**
...@@ -864,8 +865,8 @@ Subscribes to data changes. The **StorageObserver** needs to be implemented. Whe ...@@ -864,8 +865,8 @@ Subscribes to data changes. The **StorageObserver** needs to be implemented. Whe
**Parameters** **Parameters**
| Name | Type | Description | | Name | Type | Description |
| -------- | --------------------------------------------------- | ------------------------------------------------------------ | | -------- | --------------------------------------------------- | ---------------------------------------- |
| type | string | Event type. The value **change** indicates data change events. | | type | string | Event type. The value **change** indicates data change events.|
| callback | Callback&lt;[StorageObserver](#storageobserver)&gt; | Callback used to return data changes. | | callback | Callback&lt;[StorageObserver](#storageobserver)&gt; | Callback used to return data changes. |
**Example** **Example**
...@@ -891,8 +892,8 @@ Unsubscribes from data changes. ...@@ -891,8 +892,8 @@ Unsubscribes from data changes.
**Parameters** **Parameters**
| Name | Type | Description | | Name | Type | Description |
| -------- | --------------------------------------------------- | ------------------------------------------------------------ | | -------- | --------------------------------------------------- | ---------------------------------------- |
| type | string | Event type. The value **change** indicates data change events. | | type | string | Event type. The value **change** indicates data change events.|
| callback | Callback&lt;[StorageObserver](#storageobserver)&gt; | Callback used to return data changes. | | callback | Callback&lt;[StorageObserver](#storageobserver)&gt; | Callback used to return data changes. |
**Example** **Example**
...@@ -909,9 +910,9 @@ storage.off('change', observer); ...@@ -909,9 +910,9 @@ storage.off('change', observer);
**System capability**: SystemCapability.DistributedDataManager.Preferences.Core **System capability**: SystemCapability.DistributedDataManager.Preferences.Core
| Name | Type | Mandatory | Description | | Name| Type| Mandatory| Description |
| ---- | ------ | --------- | ------------- | | ---- | -------- | ---- | ---------------- |
| key | string | No | Data changed. | | key | string | No | Data changed.|
## ValueType ## ValueType
...@@ -920,7 +921,7 @@ Enumerates the value types. ...@@ -920,7 +921,7 @@ Enumerates the value types.
**System capability**: SystemCapability.DistributedDataManager.Preferences.Core **System capability**: SystemCapability.DistributedDataManager.Preferences.Core
| Type | Description | | Type | Description |
| ------- | ----------------------------- | | ------- | -------------------- |
| number | The value is a number. | | number | The value is a number. |
| string | The value is a string. | | string | The value is a string. |
| boolean | The value is of Boolean type. | | boolean | The value is of Boolean type.|
\ No newline at end of file
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