application-dev/file-management/save-user-file.md

# Saving User Files

When a user needs to download a file from the network to a local directory or save a user file into another directory, use **FilePicker** to save the file.

The operations for saving images, audio or video clips, and documents are similar. Call **save()** of the corresponding picker instance and pass in **saveOptions**. No permission is required if your application uses **FilePicker** to access files.

Currently, all the **save()** APIs of **FilePicker** can be perceived by users. Specifically, **FilePicker** is started to save the files to a directory managed by **FileManager**. The files are isolated from the assets managed by **Gallery** and cannot be viewed in **Gallery**.

To enable the saved image or video to be viewed in **Gallery**, [create the media asset using a security component](./photoAccessHelper-resource-guidelines.md#creating-a-media-asset-using-a-security-component).


## Saving Images or Videos

For example, select an image from **Gallery** and save it.

1. Import the [picker](../reference/apis/js-apis-file-picker.md), [fs](../reference/apis/js-apis-file-fs.md), [photoAccessHelper](../reference/apis/js-apis-photoAccessHelper.md), and [dataSharePredicates](../reference/apis/js-apis-data-dataSharePredicates.md) modules.

   ```ts
   import picker from '@ohos.file.picker';
   import fs from '@ohos.file.fs';
   import photoAccessHelper from '@ohos.file.photoAccessHelper';
   import dataSharePredicates from '@ohos.data.dataSharePredicates';
   ```

2. Obtain the thumbnail of the first image in the device. Before performing this operation, ensure that the device has at least one image.

   ```ts
   import common from '@ohos.app.ability.common';
   import image from '@ohos.multimedia.image';
   import { BusinessError } from '@ohos.base';

   let context = getContext(this) as common.UIAbilityContext;
   let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);

   let pixelmapArrayBuffer: ArrayBuffer;
   async function getPixelmap(): Promise<void> {
      try {
         let predicates = new dataSharePredicates.DataSharePredicates();
         let fetchOption: photoAccessHelper.FetchOptions = {
            fetchColumns: [],
            predicates: predicates
         };
         let fetchResult = await phAccessHelper.getAssets(fetchOption);
         console.info('[picker] getThumbnail fetchResult: ' + fetchResult);
         const asset = await fetchResult.getFirstObject();
         console.info('[picker] getThumbnail asset displayName = ', asset.displayName);
         asset.getThumbnail().then((pixelMap: image.PixelMap) => {
            let pixelBytesNumber = pixelMap.getPixelBytesNumber();
            const readBuffer = new ArrayBuffer(pixelBytesNumber);
            pixelMap.readPixelsToBuffer(readBuffer).then(() => {
               pixelmapArrayBuffer = readBuffer;
            })
         }).catch((err: BusinessError) => {
            console.error('[picker] getThumbnail failed with error: ' + JSON.stringify(err));
         });
      } catch (error) {
         let err: BusinessError = error as BusinessError;
         console.error('[picker] getThumbnail error = ' + JSON.stringify(err));
      }
   }
   ```

3. Create a **photoViewPicker** instance and call [save()](../reference/apis/js-apis-file-picker.md#save) to start the **FilePicker** page to save the image. After the user selects the destination folder, the image is saved and the URI of the saved image is returned.

   The permission on the URI returned by **save()** is read/write. Further file operations can be performed based on the URI. Note that the URI cannot be directly used in the **picker** callback to open a file. You need to define a global variable to save the URI and use a button to trigger file opening.

   ```ts
   import { BusinessError } from '@ohos.base';

   let uris: Array<string> = [];
   async function photoViewPickerSave(): Promise<void>{
      try {
         const photoSaveOptions = new picker.PhotoSaveOptions(); // Create a photoSaveOptions instance.
         photoSaveOptions.newFileNames = ["PhotoViewPicker01.png"]; // (Optional) Name of the file to be saved. The file name in the square brackets can be customized and must be unique. If the file name already exists in the device, change the file name. Otherwise, an error will be returned.

         const photoViewPicker = new picker.PhotoViewPicker();
         try {
            let photoSaveResult = await photoViewPicker.save(photoSaveOptions);
            if (photoSaveResult != undefined) {
               uris = photoSaveResult;
               console.info('photoViewPicker.save to file succeed and uris are:' + uris);
            }
         } catch (error) {
            let err: BusinessError = error as BusinessError;
            console.error(`[picker] Invoke photoViewPicker.save failed, code is ${err.code}, message is ${err.message}`);
         }
      } catch (error) {
         let err: BusinessError = error as BusinessError;
         console.info("[picker] photoViewPickerSave error = " + JSON.stringify(err));
      }
   }
   ```

4. After the application UI is returned from **FilePicker**, use a button to trigger the application's API. Use [fs.openSync()](../reference/apis/js-apis-file-fs.md#fsopensync) to open the image based on the URI and obtain the file descriptor (FD). Note that the **mode** parameter of **fs.openSync()** must be **fs.OpenMode.READ_WRITE**.

   Then, use [fs.write](../reference/apis/js-apis-file-fs.md#fswrite) to edit the image based on the FD. After that, use **fs.closeSync** to close the FD.

   ```ts
   import { BusinessError } from '@ohos.base';

   async function writeOnly(uri: string): Promise<void> {
      try {
         let file = fs.openSync(uri, fs.OpenMode.WRITE_ONLY);
         let writeLen = await fs.write(file.fd, pixelmapArrayBuffer);
         fs.closeSync(file);
         console.info("[picker] writeOnly writeLen = " + writeLen);
      } catch (error) {
         let err: BusinessError = error as BusinessError;
         console.info("[picker] writeOnly error: " + JSON.stringify(err));
      }
   }
   ```

## Saving Documents

1. Import the **picker** and **fs** modules.

   ```ts
   import picker from '@ohos.file.picker';
   import fs from '@ohos.file.fs';
   import { BusinessError } from '@ohos.base';
   ```

2. Create a **documentSaveOptions** instance.

   ```ts
   const documentSaveOptions = new picker.DocumentSaveOptions(); // Create a documentSaveOptions instance.
   documentSaveOptions.newFileNames = ["DocumentViewPicker01.txt"]; // (Optional) Set the name of the document to save.
   documentSaveOptions.fileSuffixChoices = ['.png', '.txt', '.mp4']; // (Optional) Types of the documents to save.
   ```

3. Create a **documentViewPicker** instance, and call [save()](../reference/apis/js-apis-file-picker.md#save-3) to open the **FilePicker** page to save the document. After the user selects the destination folder, the document is saved and the URI of the document saved is returned.

   The permission on the URI returned by **save()** is read/write. Further file operations can be performed based on the URI. Note that the URI cannot be directly used in the **picker** callback to open a file. You need to define a global variable to save the URI and use a button to trigger file opening.

   ```ts
   import { BusinessError } from '@ohos.base';

   let uris: Array<string> = [];
   const documentViewPicker = new picker.DocumentViewPicker(); // Create a documentViewPicker instance.
   documentViewPicker.save(documentSaveOptions).then((documentSaveResult: Array<string>) => {
     uris = documentSaveResult;
     console.info('documentViewPicker.save to file succeed and uris are:' + uris);
   }).catch((err: BusinessError) => {
     console.error(`Invoke documentViewPicker.save failed, code is ${err.code}, message is ${err.message}`);
   })
   ```

4. After the application UI is returned from **FilePicker**, use a button to trigger the application's API. Use [fs.openSync()](../reference/apis/js-apis-file-fs.md#fsopensync) to open the document based on the URI and obtain the FD. Note that the **mode** parameter of **fs.openSync()** must be **fs.OpenMode.READ_WRITE**.

   ```ts
   import fs from '@ohos.file.fs';

   const uri = '';
   let file = fs.openSync(uri, fs.OpenMode.READ_WRITE);
   console.info('file fd: ' + file.fd);
   ```

5. Use [fs.writeSync()](../reference/apis/js-apis-file-fs.md#writesync) to edit the document based on the FD, and then use **fs.closeSync** to close the FD.

   ```ts
   import fs from '@ohos.file.fs';

   let writeLen: number = fs.writeSync(file.fd, 'hello, world');
   console.info('write data to file succeed and size is:' + writeLen);
   fs.closeSync(file);
   ```

## Saving Audio Clips

1. Import the **picker** and **fs** modules.

   ```ts
   import picker from '@ohos.file.picker';
   import fs from '@ohos.file.fs';
   import { BusinessError } from '@ohos.base';
   ```

2. Create an **audioSaveOptions** instance.

   ```ts
   const audioSaveOptions = new picker.AudioSaveOptions(); // Create an audioSaveOptions instance.
   audioSaveOptions.newFileNames = ['AudioViewPicker01.mp3']; // (Optional) Set the name of the audio file to save.
   ```

3. Create an **audioViewPicker** instance, and call [save()](../reference/apis/js-apis-file-picker.md#save-6) to open the **FilePicker** page to save the audio clip. After the user selects the destination folder, the audio clip is saved and the URI of the audio clip saved is returned.

   The permission on the URI returned by **save()** is read/write. Further file operations can be performed based on the URI. Note that the URI cannot be directly used in the **picker** callback to open an audio clip. You need to define a global variable to save the URI and use a button to trigger the operation for opening the audio clip.

   ```ts
   let uri: string = '';
   const audioViewPicker = new picker.AudioViewPicker();
   audioViewPicker.save(audioSaveOptions).then((audioSelectResult: Array<string>) => {
     uri = audioSelectResult[0];
     console.info('audioViewPicker.save to file succeed and uri is:' + uri);
   }).catch((err: BusinessError) => {
     console.error(`Invoke audioViewPicker.save failed, code is ${err.code}, message is ${err.message}`);
   })
   ```

4. After the application UI is returned from **FilePicker**, use a button to trigger the application's API. Use [fs.openSync()](../reference/apis/js-apis-file-fs.md#fsopensync) to open the audio clip based on the URI and obtain the FD. Note that the **mode** parameter of **fs.openSync()** must be **fs.OpenMode.READ_WRITE**.

   ```ts
   let file = fs.openSync(uri, fs.OpenMode.READ_WRITE);
   console.info('file fd: ' + file.fd);
   ```

5. Use [fs.writeSync()](../reference/apis/js-apis-file-fs.md#writesync) to edit the audio clip based on the FD, and then use **fs.closeSync** to close the FD.

   ```ts
   let writeLen = fs.writeSync(file.fd, 'hello, world');
   console.info('write data to file succeed and size is:' + writeLen);
   fs.closeSync(file);
   ```