Querying Assets (ArkTS)

Available APIs

You can use query(query: AssetMap), an asynchronous API, and querySync(query: AssetMap), a synchronous API, to query assets.

The following table describes the attributes of AssetMap for querying an asset.

NOTE

In the following table, the attributes starting with DATA_LABEL are custom asset attributes reserved for services. These attributes are not encrypted. Therefore, do not put personal data in these attributes.

Attribute Name (Tag)	Value	Mandatory	Description
ALIAS	Type: Uint8Array Length: 1-256 bytes	No	Asset alias, which uniquely identifies an asset.
ACCESSIBILITY	Type: number Value range: see Accessibility	No	Access control based on the lock screen status.
REQUIRE_PASSWORD_SET	Type: boolean	No	Whether the asset is accessible only when a lock screen password is set.
AUTH_TYPE	Type: number Value range: see AuthType	No	Type of user authentication required for accessing the asset.
SYNC_TYPE	Type: number Value range: see SyncType	No	Type of sync supported by the asset.
IS_PERSISTENT	Type: boolean	No	Whether to retain the asset when the application is uninstalled.
DATA_LABEL_CRITICAL_1	Type: Uint8Array Length: 1-2048 bytes	No	Asset attribute information customized by the service with integrity protection. NOTE: The data length is 1 to 512 bytes before API version 12.
DATA_LABEL_CRITICAL_2	Type: Uint8Array Length: 1-2048 bytes	No	Asset attribute information customized by the service with integrity protection. NOTE: The data length is 1 to 512 bytes before API version 12.
DATA_LABEL_CRITICAL_3	Type: Uint8Array Length: 1-2048 bytes	No	Asset attribute information customized by the service with integrity protection. NOTE: The data length is 1 to 512 bytes before API version 12.
DATA_LABEL_CRITICAL_4	Type: Uint8Array Length: 1-2048 bytes	No	Asset attribute information customized by the service with integrity protection. NOTE: The data length is 1 to 512 bytes before API version 12.
DATA_LABEL_NORMAL_1	Type: Uint8Array Length: 1-2048 bytes	No	Asset attribute information customized by the service without integrity protection. NOTE: The data length is 1 to 512 bytes before API version 12.
DATA_LABEL_NORMAL_2	Type: Uint8Array Length: 1-2048 bytes	No	Asset attribute information customized by the service without integrity protection. NOTE: The data length is 1 to 512 bytes before API version 12.
DATA_LABEL_NORMAL_3	Type: Uint8Array Length: 1-2048 bytes	No	Asset attribute information customized by the service without integrity protection. NOTE: The data length is 1 to 512 bytes before API version 12.
DATA_LABEL_NORMAL_4	Type: Uint8Array Length: 1-2048 bytes	No	Asset attribute information customized by the service without integrity protection. NOTE: The data length is 1 to 512 bytes before API version 12.
DATA_LABEL_NORMAL_LOCAL_1¹²⁺	Type: Uint8Array Length: 1-2048 bytes	No	Local attribute information about the asset. The value is assigned by the service without integrity protection and will not be synced.
DATA_LABEL_NORMAL_LOCAL_2¹²⁺	Type: Uint8Array Length: 1-2048 bytes	No	Local attribute information about the asset. The value is assigned by the service without integrity protection and will not be synced.
DATA_LABEL_NORMAL_LOCAL_3¹²⁺	Type: Uint8Array Length: 1-2048 bytes	No	Local attribute information about the asset. The value is assigned by the service without integrity protection and will not be synced.
DATA_LABEL_NORMAL_LOCAL_4¹²⁺	Type: Uint8Array Length: 1-2048 bytes	No	Local attribute information about the asset. The value is assigned by the service without integrity protection and will not be synced.
RETURN_TYPE	Type: number Value range: see ReturnType	No	Type of the asset query result to return.
RETURN_LIMIT	Type: number	No	Maximum number of asset records to return.
RETURN_OFFSET	Type: number Value range: 1-65536	No	Offset of the asset query result. NOTE: This parameter specifies the starting asset record to return in batch asset query.
RETURN_ORDERED_BY	Type: number Value: asset.Tag.DATA_LABEL_xxx.	No	How the query results are sorted. Currently, the results can be sorted only by DATA_LABEL. NOTE: By default, assets are returned in the order in which they are added.
REQUIRE_ATTR_ENCRYPTED¹⁴⁺	Type: boolean	No	Whether to query the customized asset attribute information that is encrypted. By default, the unencrypted, customized asset attribute information is queried.
GROUP_ID¹⁸⁺	Type: Uint8Array Length: 7-127 bytes	No	Group to which the asset to be queried belongs. By default, this parameter is not specified.

Constraints

The assets queried are transmitted to the service through an IPC channel. Due to the limitation of the IPC buffer size, the maximum number of assets to be queried at a time cannot exceed 40.

Example

NOTE

The asset module provides an asynchronous API and a synchronous API for querying assets. The following uses the asynchronous API as an example. For more information about the APIs, see Asset Store Service.

For details about how to query the plaintext of an asset in a group, see Querying the Plaintext of an Asset in a Group. For details about how to query the attributes of an asset in a group, see Querying the Attributes of an Asset in a Group.

Querying the Plaintext of an Asset

Query the plaintext of asset demo_alias.

import { asset } from '@kit.AssetStoreKit';
import { util } from '@kit.ArkTS';
import { BusinessError } from '@kit.BasicServicesKit';

function stringToArray(str: string): Uint8Array {
  let textEncoder = new util.TextEncoder();
  return textEncoder.encodeInto(str);
}

function arrayToString(arr: Uint8Array): string {
  let textDecoder = util.TextDecoder.create("utf-8", { ignoreBOM: true });
  let str = textDecoder.decodeToString(arr, { stream: false })
  return str;
}

let query: asset.AssetMap = new Map();
query.set(asset.Tag.ALIAS, stringToArray('demo_alias')); // Specify the alias of the asset to query.
query.set(asset.Tag.RETURN_TYPE, asset.ReturnType.ALL); // Return all asset information, including attributes and asset plaintext.
try {
  asset.query(query).then((res: Array<asset.AssetMap>) => {
    for (let i = 0; i < res.length; i++) {
      // Parse the secret.
      let secret: Uint8Array = res[i].get(asset.Tag.SECRET) as Uint8Array;
      // Convert uint8array to string
      let secretStr: string = arrayToString(secret);
    }
  }).catch ((err: BusinessError) => {
    console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
  });
} catch (error) {
  let err = error as BusinessError;
  console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
}

Querying Attributes of an Asset

Query attributes of asset demo_alias.

import { asset } from '@kit.AssetStoreKit';
import { util } from '@kit.ArkTS';
import { BusinessError } from '@kit.BasicServicesKit';

function stringToArray(str: string): Uint8Array {
  let textEncoder = new util.TextEncoder();
  return textEncoder.encodeInto(str);
}

let query: asset.AssetMap = new Map();
query.set(asset.Tag.ALIAS, stringToArray('demo_alias')); // Specify the alias of the asset to query.
query.set(asset.Tag.RETURN_TYPE, asset.ReturnType.ATTRIBUTES); // Return only the attributes of the asset, that is, the result does not include the asset plaintext.
try {
  asset.query(query).then((res: Array<asset.AssetMap>) => {
    for (let i = 0; i < res.length; i++) {
      // Parse the attributes.
      let accessibility: number = res[i].get(asset.Tag.ACCESSIBILITY) as number;
    }
  }).catch ((err: BusinessError) => {
    console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
  });
} catch (error) {
  let err = error as BusinessError;
  console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
}

Querying Attributes of Assets

Query attributes of assets with tag 1 of demo_label and return a total of 10 records sorted by DATA_LABEL_NORMAL_1 starting from the fifth record that matches the search criteria.

import { asset } from '@kit.AssetStoreKit';
import { util } from '@kit.ArkTS';
import { BusinessError } from '@kit.BasicServicesKit';

function stringToArray(str: string): Uint8Array {
  let textEncoder = new util.TextEncoder();
  return textEncoder.encodeInto(str);
}

let query: asset.AssetMap = new Map();
query.set(asset.Tag.RETURN_TYPE, asset.ReturnType.ATTRIBUTES); // Return only the attributes of the asset, that is, the result does not include the asset plaintext.
query.set(asset.Tag.DATA_LABEL_NORMAL_1, stringToArray('demo_label'));
query.set(asset.Tag.RETURN_OFFSET, 5); // Return results from the fifth asset that matches the search criteria.
query.set(asset.Tag.RETURN_LIMIT, 10); // Return information about 10 assets that match the search criteria.
query.set(asset.Tag.RETURN_ORDERED_BY, asset.Tag.DATA_LABEL_NORMAL_1); // Sort the query results by DATA_LABEL_NORMAL_1.
try {
  asset.query(query).then((res: Array<asset.AssetMap>) => {
    for (let i = 0; i < res.length; i++) {
      // Parse the attributes.
      let accessibility: number = res[i].get(asset.Tag.ACCESSIBILITY) as number;
    }
  }).catch ((err: BusinessError) => {
    console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
  });
} catch (error) {
  let err = error as BusinessError;
  console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
}