Interface (FetchResult)
FetchResult provides APIs to manage the file retrieval result.
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.
Modules to Import
import { photoAccessHelper } from '@kit.MediaLibraryKit';
getCount
getCount(): number
Obtains the total number of files in the result set.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Return value
| Type | Description |
|---|---|
| number | Total number of files obtained. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getCountDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
let fetchCount = fetchResult.getCount();
console.info('fetchCount = ', fetchCount);
}
isAfterLast
isAfterLast(): boolean
Checks whether the cursor is in the last row of the result set.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Return value
| Type | Description |
|---|---|
| boolean | true is returned if the cursor is in the last row of the result set; false otherwise. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
let fetchCount = fetchResult.getCount();
console.info('count:' + fetchCount);
let photoAsset: photoAccessHelper.PhotoAsset = await fetchResult.getLastObject();
if (fetchResult.isAfterLast()) {
console.info('photoAsset isAfterLast displayName = ', photoAsset.displayName);
} else {
console.info('photoAsset not isAfterLast.');
}
}
close
close(): void
Closes this FetchResult instance to invalidate it. After this instance is released, the APIs in this instance cannot be invoked.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('fetchResultCloseDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
try {
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
fetchResult.close();
console.info('close succeed.');
} catch (err) {
console.error(`close fail. error: ${err.code}, ${err.message}`);
}
}
getFirstObject
getFirstObject(callback: AsyncCallback<T>): void
Obtains the first file asset in the result set. This API uses an asynchronous callback to return the result.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| callback | AsyncCallback<T> | Yes | Callback function. If the first file asset in the result set is successfully obtained, err is undefined, and data is the specific search result. Otherwise, err is an error object. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getFirstObjectDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
fetchResult.getFirstObject((err, photoAsset) => {
if (photoAsset !== undefined) {
console.info('photoAsset displayName: ', photoAsset.displayName);
} else {
console.error(`photoAsset failed with err:${err.code}, ${err.message}`);
}
});
}
getFirstObject
getFirstObject(): Promise<T>
Obtains the first file asset in the result set. This API uses a promise to return the result.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Return value
| Type | Description |
|---|---|
| Promise<T> | Promise used to return the first object in the result set. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getFirstObjectDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
let photoAsset: photoAccessHelper.PhotoAsset = await fetchResult.getFirstObject();
console.info('photoAsset displayName: ', photoAsset.displayName);
}
getNextObject
getNextObject(callback: AsyncCallback<T>): void
Obtains the next file asset in the result set. This API uses an asynchronous callback to return the result.
Before using this API, you must use isAfterLast() to check whether the current position is the end of the result set.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| callback | AsyncCallback<T> | Yes | Callback function. If the next file asset in the result set is successfully obtained, err is undefined, and data is the specific search result. Otherwise, err is an error object. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getNextObjectDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
await fetchResult.getFirstObject();
if (!fetchResult.isAfterLast()) {
fetchResult.getNextObject((err, photoAsset) => {
if (photoAsset !== undefined) {
console.info('photoAsset displayName: ', photoAsset.displayName);
} else {
console.error(`photoAsset failed with err: ${err.code}, ${err.message}`);
}
});
}
}
getNextObject
getNextObject(): Promise<T>
Obtains the next file asset in the result set. This API uses a promise to return the result.
Before using this API, you must use isAfterLast() to check whether the current position is the end of the result set.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Return value
| Type | Description |
|---|---|
| Promise<T> | Promise used to return the next object in the result set. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getNextObjectDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
await fetchResult.getFirstObject();
if (!fetchResult.isAfterLast()) {
let photoAsset: photoAccessHelper.PhotoAsset = await fetchResult.getNextObject();
console.info('photoAsset displayName: ', photoAsset.displayName);
}
}
getLastObject
getLastObject(callback: AsyncCallback<T>): void
Obtains the last file asset in the result set. This API uses an asynchronous callback to return the result.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| callback | AsyncCallback<T> | Yes | Callback function. If the last file asset in the result set is successfully obtained, err is undefined, and data is the specific search result. Otherwise, err is an error object. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getLastObjectDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
fetchResult.getLastObject((err, photoAsset) => {
if (photoAsset !== undefined) {
console.info('photoAsset displayName: ', photoAsset.displayName);
} else {
console.error(`photoAsset failed with err: ${err.code}, ${err.message}`);
}
});
}
getLastObject
getLastObject(): Promise<T>
Obtains the last file asset in the result set. This API uses a promise to return the result.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Return value
| Type | Description |
|---|---|
| Promise<T> | Promise used to return the last object in the result set. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getLastObjectDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
let photoAsset: photoAccessHelper.PhotoAsset = await fetchResult.getLastObject();
console.info('photoAsset displayName: ', photoAsset.displayName);
}
getObjectByPosition
getObjectByPosition(index: number, callback: AsyncCallback<T>): void
Obtains a file asset with the specified index in the result set. This API uses an asynchronous callback to return the result.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| index | number | Yes | Index of the file asset to obtain. The value starts from 0. |
| callback | AsyncCallback<T> | Yes | Callback function. If the file asset with the specified index in the result set is successfully obtained, err is undefined, and data is the specific search result. Otherwise, err is an error object. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getObjectByPositionDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
fetchResult.getObjectByPosition(0, (err, photoAsset) => {
if (photoAsset !== undefined) {
console.info('photoAsset displayName: ', photoAsset.displayName);
} else {
console.error(`photoAsset failed with err: ${err.code}, ${err.message}`);
}
});
}
getObjectByPosition
getObjectByPosition(index: number): Promise<T>
Obtains a file asset with the specified index in the result set. This API uses a promise to return the result.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| index | number | Yes | Index of the file asset to obtain. The value starts from 0. |
Return value
| Type | Description |
|---|---|
| Promise<T> | Promise used to return the file asset obtained. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getObjectByPositionDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
if (fetchResult === undefined) {
console.error('fetchResult is undefined');
return;
}
let photoAsset: photoAccessHelper.PhotoAsset = await fetchResult.getObjectByPosition(0);
console.info('photoAsset displayName: ', photoAsset.displayName);
}
getAllObjects
getAllObjects(callback: AsyncCallback<Array<T>>): void
Obtains all the file assets in the result set. This API uses an asynchronous callback to return the result.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| callback | AsyncCallback<Array<T>> | Yes | Callback function. If all file assets in the result set are successfully obtained, err is undefined, and data is the specific search result. Otherwise, err is an error object. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getAllObjectDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
fetchResult.getAllObjects((err, photoAssetList) => {
if (photoAssetList !== undefined) {
console.info('photoAssetList length: ', photoAssetList.length);
} else {
console.error(`photoAssetList failed with err:${err.code}, ${err.message}`);
}
});
}
getAllObjects
getAllObjects(): Promise<Array<T>>
Obtains all the file assets in the result set. This API uses a promise to return the result.
Atomic service API: This API can be used in atomic services since API version 20.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Return value
| Type | Description |
|---|---|
| Promise<Array<T>> | Promise used to return an array of all file assets. |
Error codes
For details about the error codes, see File Management Error Codes.
| ID | Error Message |
|---|---|
| 13900020 | Invalid argument. |
| 14000011 | System inner fail. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getAllObjectDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
let photoAssetList: Array<photoAccessHelper.PhotoAsset> = await fetchResult.getAllObjects();
console.info('photoAssetList length: ', photoAssetList.length);
}
contains23+
contains(object: T): Promise<boolean>
Checks whether the specified file asset is contained in the result set. This API uses a promise to return the result.
Model restriction: This API can be used only in the stage model.
Atomic service API: This API can be used in atomic services since API version 23.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| object | T | Yes | Specified file asset. |
Return value
| Type | Description |
|---|---|
| Promise<boolean> | Promise used to return the result. true indicates that the specified file asset is contained in the result set, and false indicates the opposite. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('fetchResultContainsDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
try {
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
let asset: photoAccessHelper.PhotoAsset = await fetchResult.getFirstObject();
let ret: boolean = await fetchResult.contains(asset);
console.info(`succeed. ${ret}`);
} catch (err) {
console.error(`fail. error: ${err.code}, ${err.message}`);
}
}
getObjectsByIndexSet23+
getObjectsByIndexSet(indexSet: number[]): Promise<T[]>
Obtains the file asset array corresponding to the specified index set in the result set. This API uses a promise to return the result.
Model restriction: This API can be used only in the stage model.
Atomic service API: This API can be used in atomic services since API version 23.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| indexSet | number[] | Yes | Specified index set. |
Return value
| Type | Description |
|---|---|
| Promise<T[]> | Promise object, which returns the file asset array corresponding to the specified index set. |
Error codes
For details about the error codes, see Media Library Error Codes.
| ID | Error Message |
|---|---|
| 23800151 | The scenario parameter verification fails. Possible causes: 1.The indexSet is null,undefined or empty. 2.The indexSet length is bigger than 500. 3.The max value of indexSet is equal or bigger than the fetch result length. 4.The min value of indexSet is less than 0. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('fetchResultGetObjectsByIndexSetDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
try {
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
let indexSet: number[] = [0, 1];
let ret: photoAccessHelper.PhotoAsset[] = await fetchResult.getObjectsByIndexSet(indexSet);
console.info(`succeed. ${ret.length}`);
} catch (err) {
console.error(`fail. error: ${err.code}, ${err.message}`);
}
}
getIndex23+
getIndex(object: T): Promise<number>
Obtains the index of a specified file asset in the result set. This API uses a promise to return the result.
Model restriction: This API can be used only in the stage model.
Atomic service API: This API can be used in atomic services since API version 23.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| object | T | Yes | Specified file asset. |
Return value
| Type | Description |
|---|---|
| Promise<number> | Promise used to return the result. If the object exists in the result set, the corresponding index is returned. Otherwise, -1 is returned. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('fetchResultGetIndexDemo');
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOption: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
try {
let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
let asset: photoAccessHelper.PhotoAsset = await fetchResult.getFirstObject();
let ret: number = await fetchResult.getIndex(asset);
console.info(`succeed. ${ret}`);
} catch (err) {
console.error(`fail. error: ${err.code}, ${err.message}`);
}
}
getRangeObjects23+
getRangeObjects(index: number, offset: number): Promise<T[]>
Obtains the file asset array of a specified length (second parameter) from the specified index (first parameter) in the result set. This API uses a promise to return the result.
System capability: SystemCapability.FileManagement.PhotoAccessHelper.Core
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| index | number | Yes | Index of the file asset to be obtained. The value must be greater than or equal to 0 and less than the number of objects in the result set. |
| offset | number | Yes | Number of file assets to be obtained. The value must be greater than 0. The sum of index and offset must be less than the total number of objects in the result set. Otherwise, error code 23800151 is thrown. |
Return value
| Type | Description |
|---|---|
| Promise<T[]> | Promise array. |
Error codes
For details about the error codes, see Media Library Error Codes.
| ID | Error Message |
|---|---|
| 23800151 | The scenario parameter verification fails. Possible causes: index or offset validity check failed. |
| 23800301 | Internal system error. You are advised to retry and check the logs. Possible causes: 1. The database is corrupted. 2. The file system is abnormal. |
Example
For details about how to create a phAccessHelper instance, see the example provided in photoAccessHelper.getPhotoAccessHelper.
import { dataSharePredicates } from '@kit.ArkData';
import { photoAccessHelper} from '@kit.MediaLibraryKit';
async function example(phAccessHelper: photoAccessHelper.PhotoAccessHelper) {
console.info('getRangeObjectsDemo');
type PhotoAsset = photoAccessHelper.PhotoAsset;
let testNum: string = "getRangeObjects_test_003";
let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
let fetchOptions: photoAccessHelper.FetchOptions = {
fetchColumns: [],
predicates: predicates
};
let fetchResult1: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> =
await phAccessHelper.getAssets(fetchOptions);
let fetchResult2: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> =
await phAccessHelper.getAssets(fetchOptions);
let count: number = fetchResult1.getCount();
const half: number = Math.ceil(count / 2);
let promises: Promise<PhotoAsset[]>[] = [];
promises[0] = fetchResult1.getRangeObjects(0, half);
promises[1] = fetchResult2.getRangeObjects(half, count - half);
let photoAssetsArray: PhotoAsset[][] = await Promise.all(promises);
let photoAssets: PhotoAsset[] = photoAssetsArray[0].concat(photoAssetsArray[1]);
console.info('photoAssets length: ', photoAssets.length);
}