@@ -30,9 +30,9 @@ The preference persistent file of an application is stored in the application sa
The following table lists the APIs used for persisting user preference data. For more information about the APIs, see [User Preferences](../reference/apis/js-apis-data-preferences.md).
| putSync(key: string, value: ValueType): void | Writes data to the Preferences instance. You can use **flush()** to persist the **Preferences** instance data. An asynchronous API is also provided. |
| hasSync(key: string): void | Checks whether the **Preferences** instance contains a KV pair with the given key. The key cannot be empty. An asynchronous API is also provided. |
| getSync(key: string, defValue: ValueType): void | Obtains the value of the specified key. If the value is null or not of the default value type, **defValue** is returned. An asynchronous API is also provided. |
...
...
@@ -40,7 +40,7 @@ The following table lists the APIs used for persisting user preference data. For
| flush(callback: AsyncCallback<void>): void | Flushes the data of this **Preferences** instance to a file for data persistence. |
| on(type: 'change', callback: Callback<{ key : string }>): void | Subscribes to data changes of the specified key. When the value of the specified key is changed and saved by **flush()**, a callback will be invoked to return the new data. |
| off(type: 'change', callback?: Callback<{ key : string }>): void | Unsubscribes from data changes. |
| deletePreferences(context: Context, name: string, callback: AsyncCallback<void>): void | Deletes a **Preferences** instance from memory. If the **Preferences** instance has a persistent file, this API also deletes the persistent file.|
| deletePreferences(context: Context, name: string, callback: AsyncCallback<void>): void | Deletes a **Preferences** instance from memory. If the **Preferences** instance has a persistent file, this API also deletes the persistent file. |
## How to Develop
...
...
@@ -58,11 +58,13 @@ The following table lists the APIs used for persisting user preference data. For
console.error(`Failed to get preferences. Code:${err.code},message:${err.message}`);
return;
...
...
@@ -102,7 +105,7 @@ The following table lists the APIs used for persisting user preference data. For
3. Write data.
Use **putSync()** to write data to the cached **Preferences** instance. After data is written, you can use **flush()** to persist the **Preferences** instance data to a file if necessary.
Use **putSync()** to save data to the cached **Preferences** instance. After data is written, you can use **flush()** to persist the **Preferences** instance data to a file if necessary.
> **NOTE**
>
...
...
@@ -157,7 +160,7 @@ The following table lists the APIs used for persisting user preference data. For
```js
try{
preferences.flush((err)=>{
preferences.flush((err:BusinessError)=>{
if(err){
console.error(`Failed to flush. Code:${err.code}, message:${err.message}`);
return;
...
...
@@ -174,18 +177,20 @@ The following table lists the APIs used for persisting user preference data. For
Specify an observer as the callback to return the data changes for an application. When the value of the subscribed key is changed and saved by **flush()**, the observer callback will be invoked to return the new data. Example:
@@ -32,7 +32,7 @@ The underlying devices manage the data by device. The device KV stores support d
The **DatamgrService** provides the following synchronization types:
- Manual synchronization: The application calls **sync()** to trigger a synchronization. The list of devices to be synchronized and the synchronization mode must be specified. The synchronization mode can be **PULL_ONLY** (pulling remote data to the local end), **PUSH_ONLY** (pushing local data to the remote end), or **PUSH_PULL** (pushing local data to the remote end and pulling remote data to the local end). You can use the [**sync()** with the **query** parameter](../reference/apis/js-apis-distributedKVStore.md#sync-1) to synchronize the data that meets the specified conditions. The manual synchronization is available only for system applications.
- Manual synchronization: The application calls **sync()** to trigger a synchronization. The list of devices to be synchronized and the synchronization mode must be specified. The synchronization mode can be **PULL_ONLY** (pulling remote data to the local end), **PUSH_ONLY** (pushing local data to the remote end), or **PUSH_PULL** (pushing local data to the remote end and pulling remote data to the local end). You can use the [**sync()** with the **query** parameter](../reference/apis/js-apis-distributedKVStore.md#sync-1) to synchronize the data that meets the specified conditions.
- Automatic synchronization: The distributed database automatically pushes local data to the remote end and pulls remote data to the local end. An automatic synchronization is triggered when a device goes online or an application updates data.
...
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@@ -72,8 +72,6 @@ When data is added, deleted, or modified, a notification is sent to the subscrib
- Each KV store supports a maximum of eight callbacks for subscription of data change notifications.
- The manual synchronization is available only for system applications.
## Available APIs
...
...
@@ -247,24 +245,21 @@ The following uses a single KV store as an example to describe how to implement
> **NOTE**
>
> If manual synchronization is used, **deviceIds** is obtained by using [devManager.getTrustedDeviceListSync](../reference/apis/js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are all system interfaces and available only to system applications.
> If manual synchronization is used, **deviceIds** can be obtained by [devManager.getAvailableDeviceListSync](../reference/apis/js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
@@ -10,9 +10,16 @@ You can synchronize the application data in a local RDB store on a device to oth
OpenHamony supports synchronization of the relational data of an application across multiple devices.
- Distributed table list<br>After a table is created for an application in an RDB store, you can set it as a distributed table. When querying the RDB store of a remote device, you can obtain the distributed table name of the remote device based on the local table name.
- Distributed table list
- Synchronization mode<br>Data can be synchronized between devices in either of the following ways: <br>- Pushing data from a local device to a remote device. <br>- Pulling data from a remote device to a local device.
After a table is created for an application in an RDB store, you can set it as a distributed table. When querying the RDB store of a remote device, you can obtain the distributed table name of the remote device based on the local table name.
- Synchronization mode
Data can be synchronized between devices in either of the following ways:
- Pushing data from a local device to a remote device.
- Pulling data from a remote device to a local device.
## Working Principles
...
...
@@ -44,12 +51,10 @@ When data is added, deleted, or modified, a notification is sent to the subscrib
- Each RDB store supports a maximum of eight callbacks for subscription of data change notifications.
- Third-party applications cannot call the distributed APIs that must be specified with the device.
## Available APIs
The following table lists the APIs for cross-device data synchronization of RDB stores. Most of the APIs are executed asynchronously, using a callback or promise to return the result. The following table uses the callback-based APIs as an example. For more information about the APIs, see [RDB Store](../reference/apis/js-apis-data-relationalStore.md).
Most of the APIs for cross-device data synchronization of RDB stores are executed asynchronously in callback or promise mode. The following table uses the callback-based APIs as an example. For more information about the APIs, see [RDB Store](../reference/apis/js-apis-data-relationalStore.md).
| API| Description|
| -------- | -------- |
...
...
@@ -73,7 +78,7 @@ The following table lists the APIs for cross-device data synchronization of RDB
1. Request the **ohos.permission.DISTRIBUTED_DATASYNC** permission. For details, see [Declaring Permissions in the Configuration File](../security/accesstoken-guidelines.md#declaring-permissions-in-the-configuration-file).
2. Display a dialog box to ask authorization from the user when the application is started for the first time. For details, see [Requesting User Authorization](../security/accesstoken-guidelines.md#requesting-user-authorization).
...
...
@@ -142,20 +147,19 @@ The following table lists the APIs for cross-device data synchronization of RDB
> **NOTE**
>
> **deviceIds** is obtained by using [devManager.getTrustedDeviceListSync](../reference/apis/js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are all system interfaces and available only to system applications.
> The value of **deviceIds** can be obtained by [deviceManager.getAvailableDeviceListSync](../reference/apis/js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
@@ -57,13 +57,14 @@ Before implementing a **DataShare** service, you need to create a **DataShareExt
2. Right-click the **DataShareAbility** directory, and choose **New > TypeScript File** to create a file named **DataShareExtAbility.ts**.
3. Import **@ohos.application.DataShareExtensionAbility** and other dependencies to the **DataShareExtAbility.ts** file, and
override the service implementation as required. For example, if the data provider provides only the data insertion, deletion, and query services, you can override only these APIs.
3. Import **@ohos.application.DataShareExtensionAbility** and other dependencies to the **DataShareExtAbility.ts** file, and override the service implementation as required. For example, if the data provider provides only the data insertion, deletion, and query services, you can override only these APIs.
4. Implement the data provider services. For example, implement data storage of the data provider by using a database, reading and writing files, or accessing the network.
...
...
@@ -75,20 +76,20 @@ override the service implementation as required. For example, if the data provid
+TBL_NAME
+' (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER, isStudent BOOLEAN, Binary BINARY)';
@@ -29,7 +29,7 @@ Currently, the UDMF provides the public data channel for cross-application data
## Available APIs
The following table lists the UDMF APIs. All of them are executed asynchronously in callback or promise mode. In the following table, callback-based APIs are used as an example. For more information about the APIs, see [UDMF](../reference/apis/js-apis-data-udmf.md).
The following table lists the UDMF APIs. All of them are executed asynchronously in callback or promise mode. In the following table, callback-based APIs are used as an example. For more information about the APIs, see [Unified Data Channel](../reference/apis/js-apis-data-unifiedDataChannel.md) and [Standard Data Definition and Description](../reference/apis/js-apis-data-uniformTypeDescriptor.md).
To streamline cross-application data interaction of OpenHarmony and minimize the application/service data interaction costs, the Unified Data Management Framework (UDMF) provides standard data definitions to define common data types. Applications can use the APIs provided by the UDMF to create and use these data types.
For example, in the cross-application drag scenario, the application of the drag source writes the data to be dragged to a [drag event](../reference/arkui-ts/ts-universal-events-drag-drop.md#dragevent) based on the standard data definitions. The application of the drop target reads the dragged data from the drag event and parses the data based on the standard data definitions. The data dragged between different applications complies with the same standard definitions, which avoids exhaustive data type adaptation and effectively reduces the development workload.
## Unified Data Types
The UDMF provides the following unified data types:
**Basic data types**<br>Basic data types include File and Text, which can be used for cross-application and cross-platform data interaction. Figure 1 and Figure 2 illustrate the basic data types.
**Basic data types**
Basic data types include File and Text, which can be used for cross-application and cross-platform data interaction. Figure 1 and Figure 2 illustrate the basic data types.
**Figure 1** UDMF File
Figure 2 UDMF Text
**Figure 2** UDMF Text
**System Defined Types (SDTs)**<br>The SDTs are specific to the platform or operating system, such as Form (UI card information), AppItem (app description information), and PixelMap (thumbnail). This type of data can be used for cross-application data interaction in a system or platform. Figure 3 illustrates the SDT data.
**System Defined Types (SDTs)**
The SDTs are specific to the platform or operating system, such as Form (UI card information), AppItem (app description information), and PixelMap (thumbnail). This type of data can be used for cross-application data interaction in a system or platform. Figure 3 illustrates the SDT data.
**Figure 3** UDMF SDT data
**App Defined Type (ADT)**<br>The SDT data is application-specific. This type of data can be used for across-platform data interaction for an application. As shown in Figure 4, the MyFile file format can be defined for use in an application ecosystem.
**App Defined Type (ADT)**
The SDT data is application-specific. This type of data can be used for across-platform data interaction for an application. As shown in Figure 4, the MyFile file format can be defined for use in an application ecosystem.
**Figure 4** UDMF ADT data
...
...
@@ -39,9 +46,9 @@ Figure 2 UDMF Text
## Available APIs
The UDMF provides the unified data object **UnifiedData** to encapsulate a group of data records **UnifiedRecord**. **UnifiedRecord** is an abstract definition of data content supported by the UDMF, for example, a text record or an image record. The data content type in a data record corresponds to **UnifiedDataType**.
The UDMF provides the unified data object **UnifiedData** to encapsulate a group of data records **UnifiedRecord**. **UnifiedRecord** is an abstract definition of data content supported by the UDMF, for example, a text record or an image record. The data content type in a data record corresponds to **UniformDataType**.
The following table describes common UDMF APIs. For more information, see [UDMF](../reference/apis/js-apis-data-udmf.md).
The following table describes common UDMF APIs. For more information about the APIs, see [Unified Data Channel](../reference/apis/js-apis-data-unifiedDataChannel.md) and [Standard Data Definition and Description](../reference/apis/js-apis-data-uniformTypeDescriptor.md).
@@ -4,11 +4,10 @@ The **DataShareExtensionAbility** module provides data share services based on t
>**NOTE**
>
> The initial APIs of this module are supported since API version 9. 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 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.
>
> The APIs provided by this module are system APIs.
> - The APIs provided by this module are system APIs and can be used only in the stage model.
>
> The APIs of this module can be used only in the stage model.
## Modules to Import
...
...
@@ -50,17 +49,17 @@ let TBL_NAME = 'TBL00';
letDDL_TBL_CREATE='CREATE TABLE IF NOT EXISTS '
+TBL_NAME
+' (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER, phoneNumber DOUBLE, isStudent BOOLEAN, Binary BINARY)';
@@ -4,9 +4,9 @@ The **DataShareResultSet** module provides APIs for accessing the result set obt
> **NOTE**
>
> The initial APIs of this module are supported since API version 9. 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 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.
>
> The APIs provided by this module are system APIs.
> - The APIs provided by this module are system APIs.
## Modules to Import
...
...
@@ -22,8 +22,9 @@ You can call [query()](js-apis-data-dataShare.md#query) to obtain the **DataShar
# @ohos.data.uniformTypeDescriptor (Standard Data Definition)
The **uniformTypeDescriptor** module provides abstract definitions of OpenHarmony standardized data types.
> **NOTE**
>
> The initial APIs of this module are supported since API version 10. Newly added APIs will be marked with a superscript to indicate their earliest API version.
@@ -12,8 +12,7 @@ The **distributedKVStore** module provides the following functions:
> **NOTE**
>
> - The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.
> - All the APIs that need to obtain **deviceId** in this module are available only to system applications.
> The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.
Creates a **Query** object with the device ID as the key prefix.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Deletes data of a device. This API uses an asynchronous callback to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Deletes data of a device. This API uses a promise to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Synchronizes the KV store manually. For details about the synchronization modes of KV stores, see [Cross-Device Synchronization of KV Stores](../../database/data-sync-of-kv-store.md).
> **NOTE**
>
> **deviceIds** is the **networkId** in [DeviceInfo](js-apis-device-manager.md#deviceinfo), which is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceIds** is **networkId** in [DeviceBasicInfo](js-apis-distributedDeviceManager.md#devicebasicinfo), which can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
Synchronizes the KV store manually. This API returns the result synchronously. For details about the synchronization modes of KV stores, see [Cross-Device Synchronization of KV Stores](../../database/data-sync-of-kv-store.md).
> **NOTE**
>
> **deviceIds** is the **networkId** in [DeviceInfo](js-apis-device-manager.md#deviceinfo), which is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceIds** is **networkId** in [DeviceBasicInfo](js-apis-distributedDeviceManager.md#devicebasicinfo), which can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
Obtains a string value that matches the specified device ID and key. This API uses an asynchronous callback to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains a string value that matches the specified device ID and key. This API uses a promise to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains all KV pairs that match the specified device ID and key prefix. This API uses an asynchronous callback to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains all KV pairs that match the specified device ID and key prefix. This API uses a promise to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains the KV pairs that match the specified device ID and **Query** object. This API uses an asynchronous callback to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains the KV pairs that match the specified device ID and **Query** object. This API uses a promise to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains a **KVStoreResultSet** object that matches the specified device ID and key prefix. This API uses an asynchronous callback to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains a **KVStoreResultSet** object that matches the specified device ID and key prefix. This API uses a promise to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains a **KVStoreResultSet** object that matches the specified device ID and **Query** object. This API uses an asynchronous callback to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains a **KVStoreResultSet** object that matches the specified device ID and **Query** object. This API uses a promise to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains a **KVStoreResultSet** object that matches the specified **Query** object for this device. This API uses an asynchronous callback to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains a **KVStoreResultSet** object that matches the specified predicate object and device ID. This API uses an asynchronous callback to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains a **KVStoreResultSet** object that matches the specified predicate object and device ID. This API uses a promise to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains the number of results that matches the specified device ID and **Query** object. This API uses an asynchronous callback to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
Obtains the number of results that matches the specified device ID and **Query** object. This API uses a promise to return the result.
> **NOTE**
>
> **deviceId** is obtained by [deviceManager.getTrustedDeviceListSync](js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are system interfaces and available only to system applications.
> **deviceId** can be obtained by [deviceManager.getAvailableDeviceListSync](js-apis-distributedDeviceManager.md#getavailabledevicelistsync).
> For details about how to obtain **deviceId**, see [sync()](#sync).
