Download files

There are three ways of getting data that was previously uploaded:

Download File

You can download file to a local directory using Amplify.Storage.downloadFile.

You can use the path_provider package to create a local file in the user's documents directory where you can store the downloaded data.

1import 'package:path_provider/path_provider.dart';
2
3Future<void> downloadToLocalFile(String key) async {
4  final documentsDir = await getApplicationDocumentsDirectory();
5  final filepath = documentsDir.path + '/example.txt';
6  try {
7    final result = await Amplify.Storage.downloadFile(
8      key: key,
9      localFile: AWSFile.fromPath(filepath),
10      onProgress: (progress) {
11        safePrint('Fraction completed: ${progress.fractionCompleted}');
12      },
13    ).result;
14
15    safePrint('Downloaded file is located at: ${result.localFile.path}');
16  } on StorageException catch (e) {
17    safePrint(e.message);
18  }
19}

Download data

You can download a file to in-memory buffer with Amplify.Storage.downloadData:

1Future<void> downloadToMemory(String key) async {
2  try {
3    final result = await Amplify.Storage.downloadData(
4      key: key,
5      onProgress: (progress) {
6        safePrint('Fraction completed: ${progress.fractionCompleted}');
7      },
8    ).result;
9
10    safePrint('Downloaded data: ${result.bytes}');
11  } on StorageException catch (e) {
12    safePrint(e.message);
13  }
14}

Generate a download URL

You can get a downloadable URL for the file in storage by its key and access level.

When creating a downloadable URL, you can choose to check if the file exists by setting validateObjectExistence to true in S3GetUrlPluginOptions. If the file is inaccessible or does not exist, a StorageException is thrown. This allows you to check if an object exists during generating the presigned URL, which you can then use to download that object.

1Future<String> getDownloadUrl({
2  required String key,
3  required StorageAccessLevel accessLevel,
4}) async {
5  try {
6    final result = await Amplify.Storage.getUrl(
7      key: key,
8      options: const StorageGetUrlOptions(
9        accessLevel: accessLevel,
10        pluginOptions: S3GetUrlPluginOptions(
11          validateObjectExistence: true,
12          expiresIn: Duration(days: 1),
13        ),
14      ),
15    ).result;
16    return result.url.toString();
17  } on StorageException catch (e) {
18    safePrint('Could not get a downloadable URL: ${e.message}');
19    rethrow;
20  }
21}

Upload files

Get file properties