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.

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}`);
}

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