harmony 鸿蒙Sharing Data Using DataShareExtensionAbility

2023-06-24
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Sharing Data Using DataShareExtensionAbility

When to Use

If complex services are involved in cross-application data access, you can use DataShareExtensionAbility to start the application of the data provider to implement data access.

You need to implement flexible service logics via callbacks of the service provider.

Working Principles

There are two roles in DataShare:

Data provider: implements operations, such as adding, deleting, modifying, and querying data, and opening a file, using DataShareExtensionAbility.
Data consumer: accesses the data provided by the provider using createDataShareHelper().

Figure 1 Data sharing mechanism dataShare

The DataShareExtensionAbility module, as the data provider, implements services related to data sharing between applications.
The DataShareHelper module, as the data consumer, provides APIs for accessing data, including adding, deleting, modifying, and querying data.
The data consumer communicates with the data provider via inter-process communication (IPC). The data provider can be implemented through a database or other data storage.
The ResultSet module is implemented through shared memory. Shared memory stores the result sets, and interfaces are provided to traverse result sets.

How to Develop

Data Provider Application Development (Only for System Applications)

The DataShareExtensionAbility provides the following APIs. You can override these APIs as required.

onCreate: called by the server to initialize service logic when the DataShare client connects to the DataShareExtensionAbility server.
insert: called to insert data upon the request of the client. Data insertion must be implemented in this callback on the server.
update: called to update data upon the request of the client. Data update must be implemented in this callback on the server.
batchUpdate: called to update batch data upon the request of the client. Batch data update must be implemented in this callback on the server.
delete: called to delete data upon the request of the client. Data deletion must be implemented in this callback on the server.
query: called to query data upon the request of the client. Data query must be implemented in this callback on the server.
batchInsert: called to batch insert data upon the request of the client. Batch data insertion must be implemented in this callback on the server.
normalizeUri: converts the URI provided by the client to the URI used by the server.
denormalizeUri: converts the URI used by the server to the initial URI passed by the client.

Before implementing a DataShare service, you need to create a DataShareExtensionAbility object in the DevEco Studio project as follows:

In the ets directory of the Module project, right-click and choose New > Directory to create a directory named DataShareExtAbility.
Right-click the DataShareExtAbility directory, and choose New > ArkTS File to create a file named DataShareExtAbility.ets.
In the DataShareExtAbility.ets file, import the DataShareExtensionAbility module. You can override the service implementation as required. For example, if the data provider provides only the insert, delete, and query services, you can override only these APIs and import the dependency modules. If permission verification is required, override the callbacks using getCallingPid, getCallingUid, and getCallingTokenId provided by the IPC module to obtain the data consumer information for permission verification.

   import { DataShareExtensionAbility, dataShare, dataSharePredicates, relationalStore, DataShareResultSet } from '@kit.ArkData';
   import { Want } from '@kit.AbilityKit';
   import { BusinessError } from '@kit.BasicServicesKit'

Implement the data provider services. For example, implement data storage of the data provider by creating and using a database, reading and writing files, or accessing the network.

   const DB_NAME = 'DB00.db';
   const TBL_NAME = 'TBL00';
   const DDL_TBL_CREATE = "CREATE TABLE IF NOT EXISTS "
     + TBL_NAME
     + ' (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER, isStudent BOOLEAN, Binary BINARY)';

   let rdbStore: relationalStore.RdbStore;
   let result: string;

   export default class DataShareExtAbility extends DataShareExtensionAbility {
     // Override onCreate().
     onCreate(want: Want, callback: Function) {
       result = this.context.cacheDir + '/datashare.txt';
       // Create an RDB store.
       relationalStore.getRdbStore(this.context, {
         name: DB_NAME,
         securityLevel: relationalStore.SecurityLevel.S3
       }, (err:BusinessError, data:relationalStore.RdbStore) => {
         rdbStore = data;
         rdbStore.executeSql(DDL_TBL_CREATE, [], (err) => {
           console.info(`DataShareExtAbility onCreate, executeSql done err:${err}`);
         });
         if (callback) {
           callback();
         }
       });
     }

     // Override query().
     query(uri: string, predicates: dataSharePredicates.DataSharePredicates, columns: Array<string>, callback: Function) {
       if (predicates === null||predicates === undefined) {
         console.info('invalid predicates');
       }
       try {
         rdbStore.query(TBL_NAME, predicates, columns, (err:BusinessError, resultSet:relationalStore.ResultSet) => {
           if (resultSet !== undefined) {
             console.info(`resultSet.rowCount:${resultSet.rowCount}`);
           }
           if (callback !== undefined) {
             callback(err, resultSet);
           }
         });
       } catch (err) {
         let code = (err as BusinessError).code;
         let message = (err as BusinessError).message
         console.error(`Failed to query. Code:${code},message:${message}`);
       }
     }
     // Override the batchUpdate API.
     batchUpdate(operations:Record<string, Array<dataShare.UpdateOperation>>, callback:Function) {
       let recordOps : Record<string, Array<dataShare.UpdateOperation>> = operations;
       let results : Record<string, Array<number>> = {};
       let a = Object.entries(recordOps);
       for (let i = 0; i < a.length; i++) {
         let key = a[i][0];
         let values = a[i][1];
         let result : number[] = [];
         for (const value of values) {
           rdbStore.update(TBL_NAME, value.values, value.predicates).then(async (rows) => {
             console.info('Update row count is ' + rows);
             result.push(rows);
           }).catch((err:BusinessError) => {
             console.info('Update failed, err is ' + JSON.stringify(err));
             result.push(-1)
           })
         }
         results[key] = result;
       }
       callback(null, results);
     }

     batchInsert(uri: string, valueBuckets:Array<ValuesBucket>, callback:Function) {
       if (valueBuckets == null||valueBuckets.length == undefined) {
        return;
       }
       let resultNum = valueBuckets.length
       rdbStore.batchInsert(TBL_NAME, valueBuckets, (err, ret) => {
        if (callback !== undefined) {
          callback(err, ret);
        }
       });
     }

     async normalizeUri(uri: string, callback:Function) {
       let ret = "normalize+" + uri;
       let err:BusinessError = {
         message: "message",
         code: 0,
         name: 'name'
       };
       await callback(err, ret);
     }

     async denormalizeUri(uri: string, callback:Function) {
       let ret = "denormalize+" + uri;

       let err:BusinessError = {
         message: "message",
         code: 0,
         name: 'name'
       };
       await callback(err, ret);
     }
     // Override other APIs as required.
   };

Define DataShareExtensionAbility in module.json5.

Table 1 Fields in module.json5

|Field|Description|Mandatory| |——–|——–|——–| |name|Ability name, corresponding to the ExtensionAbility class name derived from Ability.|Yes| |type|Ability type. The value dataShare indicates that the development is based on the datashare template.|Yes| |uri|Unique identifier for the data consumer to access the data provider.|Yes| |exported|Whether it is visible to other applications. Data sharing is allowed only when the value is true.|Yes| |readPermission|Permission required for accessing data. If this parameter is not set, read permission verification is not performed by default.
NOTE: The permission constraints for DataShareExtensionAbility are different from that for silent access. It is important to understand the difference and prevent confusion. For details, see Silent Access via DatamgrService.|No| |writePermission|Permission required for modifying data. If this parameter is not set, write permission verification is not performed by default.
NOTE: The permission constraints for DataShareExtensionAbility are different from that for silent access. It is important to understand the difference and prevent confusion. For details, see Silent Access via DatamgrService.|No| |metadata |Silent access configuration, which includes the following:
name: identifies the configuration, which has a fixed value of ohos.extension.dataShare.
resource: has a fixed value of $profile:data_share_config, which indicates that the profile name is data_share_config.json.|metadata is mandatory when the ability launch type is singleton. For details about the ability launch type, see launchType in the Internal Structure of the abilities Attribute.|

module.json5 example

   // The following uses settingsdata as an example.
   "extensionAbilities": [
     {
       "srcEntry": "./ets/DataAbility/DataExtAbility.ets",
       "name": "DataExtAbility",
       "icon": "$media:icon",
       "description": "$string:description_datashareextability",
       "type": "dataShare",
       "uri": "datashare://com.ohos.settingsdata.DataAbility",
       "exported": true,
       // Configure permissions based on actual situation. The permissions configured here are examples only.
       "readPermission": "ohos.permission.MANAGE_SECURE_SETTINGS",
       "writePermission": "ohos.permission.MANAGE_SECURE_SETTINGS",
       "metadata": [{"name": "ohos.extension.dataShare", "resource": "$profile:data_share_config"}]
     }
   ]

Table 2 Fields in the data_share_config.json file

|Field |Description |Mandatory| |——————-|————————————————————|—-| |tableConfig |Configuration label, which includes uri and crossUserMode.
- uri: specifies the range for which the configuration takes effect. The URI supports the following formats in descending order by priority:
1. *****: indicates all databases and tables.
2. datashare:///{bundleName}/{moduleName}/{storeName}: specifies a database.
3. datashare:///{bundleName}/{moduleName}/{storeName}/{tableName}: specifies a table.
If URIs of different formats are configured, only the URI with the higher priority takes effect.
- crossUserMode: Whether to share data between multiple users.
The value 1 means to share data between multiple users, and the value 2 means the opposite.|Yes| |isSilentProxyEnable|Whether to enable silent access for this ExtensionAbility.
false: Silent access is disabled.
true: Silent access is enabled.
The default value is true.
If an application has multiple ExtensionAbilities and this field is set to false for one of them, silent access is disabled for the application.
If the data provider has called enableSilentProxy or disableSilentProxy, silent access is enabled or disabled based on the API settings. Otherwise, the setting here takes effect.|No| |launchInfos |Information including storeId and tableNames.
If the data in a table involved in the configuration changes, an extensionAbility will be started based on the URI in extensionAbilities. You need to set this parameter only when the service needs to start an extensionAbility to process data that is not actively changed by the service.
- storeId: database name, excluding the file name extension. For example, if the database name is test.db, set this parameter to test.
- tableNames: names of the database tables. Any change in a table will start extension.|No|

data_share_config.json Example

   {
       "tableConfig":[
           {
               "uri":"*",
               "crossUserMode":1
           },
           {
               "uri":"datashare:///com.ohos.settingsdata/entry/DB00",
               "crossUserMode":1
           },
           {
               "uri":"datashare:///com.acts.datasharetest/entry/DB00/TBL00",
               "crossUserMode":2
           }
       ],
       "isSilentProxyEnable":true,
       "launchInfos":[
           {
               "storeId": "test",
               "tableNames":["test1", "test2"]
           }
       ]
   }

Data Consumer Application Development

Import the dependencies.

   import { UIAbility } from '@kit.AbilityKit';
   import { dataShare, dataSharePredicates, DataShareResultSet, ValuesBucket } from '@kit.ArkData';
   import { window } from '@kit.ArkUI';
   import { BusinessError } from '@kit.BasicServicesKit';

Define the URI string for communicating with the data provider.
The URI is the identifier of the context data provider in set in the configuration file. It can be added with suffix parameters to set the access target. The suffix parameters must start with a question mark (?).
- Currently, only the user parameter is supported.
- The value of user must be an integer. It indicates the user ID of the data provider. If It is not specified, the user ID of the data consumer is used. For details about the definition of user and how to obtain it, see user.
- Currently, the data consumer in cross-user access must have the ohos.permission.INTERACT_ACROSS_LOCAL_ACCOUNTS permission. Currently, cross-user access supports the add, delete, modify, and query operations, and does not support subscription notification.

   // Different from the URI defined in the module.json5 file, the URI passed in the parameter has an extra slash (/), because there is a DeviceID parameter between the second and the third slash (/).
   let dseUri = ('datashare:///com.ohos.settingsdata.DataAbility');

Create a DataShareHelper instance.

   let dsHelper: dataShare.DataShareHelper|undefined = undefined;
   let abilityContext: Context;

   export default class EntryAbility extends UIAbility {
     onWindowStageCreate(windowStage: window.WindowStage) {
       abilityContext = this.context;
       dataShare.createDataShareHelper(abilityContext, dseUri, (err, data) => {
         dsHelper = data;
       });
     }
   }

Use the APIs provided by DataShareHelper to access the services provided by the provider, for example, adding, deleting, modifying, and querying data.

   // Construct a piece of data.
   let key1 = 'name';
   let key2 = 'age';
   let key3 = 'isStudent';
   let key4 = 'Binary';
   let valueName1 = 'ZhangSan';
   let valueName2 = 'LiSi';
   let valueAge1 = 21;
   let valueAge2 = 18;
   let valueIsStudent1 = false;
   let valueIsStudent2 = true;
   let valueBinary = new Uint8Array([1, 2, 3]);
   let valuesBucket: ValuesBucket = { key1: valueName1, key2: valueAge1, key3: valueIsStudent1, key4: valueBinary };
   let updateBucket: ValuesBucket = { key1: valueName2, key2: valueAge2, key3: valueIsStudent2, key4: valueBinary };
   let predicates = new dataSharePredicates.DataSharePredicates();
   let valArray = ['*'];
   
   let record: Record<string, Array<dataShare.UpdateOperation>> = {};
   let operations1: Array<dataShare.UpdateOperation> = [];
   let operations2: Array<dataShare.UpdateOperation> = [];
   let operation1: dataShare.UpdateOperation = {
     values: valuesBucket,
     predicates: predicates
   }
   operations1.push(operation1);
   let operation2: dataShare.UpdateOperation = {
     values: updateBucket,
     predicates: predicates
   }
   operations2.push(operation2);
   record["uri1"] = operations1;
   record["uri2"] = operations2;
   
   if (dsHelper != undefined) {
     // Insert a piece of data.
     (dsHelper as dataShare.DataShareHelper).insert(dseUri, valuesBucket, (err:BusinessError, data:number) => {
       console.info(`dsHelper insert result:${data}`);
     });
     // Update data.
     (dsHelper as dataShare.DataShareHelper).update(dseUri, predicates, updateBucket, (err:BusinessError, data:number) => {
       console.info(`dsHelper update result:${data}`);
     });
     // Query data.
     (dsHelper as dataShare.DataShareHelper).query(dseUri, predicates, valArray, (err:BusinessError, data:DataShareResultSet) => {
       console.info(`dsHelper query result:${data}`);
     });
     // Delete data.
     (dsHelper as dataShare.DataShareHelper).delete(dseUri, predicates, (err:BusinessError, data:number) => {
       console.info(`dsHelper delete result:${data}`);
     });
     // Update data in batches.
     (dsHelper as dataShare.DataShareHelper).batchUpdate(record).then((data: Record<string, Array<number>>) => {
        // Traverse data to obtain the update result of each data record. value indicates the number of data records that are successfully updated. If value is less than 0, the update fails.
        let a = Object.entries(data);
        for (let i = 0; i < a.length; i++) {
          let key = a[i][0];
          let values = a[i][1]
          console.info(`Update uri:${key}`);
          for (const value of values) {
            console.info(`Update result:${value}`);
          }
        }
      });
     // Close the DataShareHelper instance.
     (dsHelper as dataShare.DataShareHelper).close();
   }