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Dart and Flutter

There is no official AWS SDK for Dart, but the minio Dart package is a mature S3 client that works against any S3-compatible service.

Install​

pubspec.yaml
dependencies:
  minio: ^3.5.0

Initialize the client​

lib/filebase.dart
import 'package:minio/minio.dart';

final filebase = Minio(
  endPoint: 's3.filebase.io',
  accessKey: const String.fromEnvironment('FILEBASE_KEY'),
  secretKey: const String.fromEnvironment('FILEBASE_SECRET'),
  region: 'auto',
  useSSL: true,
);

List buckets​

final buckets = await filebase.listBuckets();
for (final b in buckets) {
  print(b.name);
}

Create a bucket​

await filebase.makeBucket('my-bucket');

Upload an object​

import 'dart:io';

final file = File('photo.jpg');
final stream = file.openRead().cast<List<int>>();
final length = await file.length();

await filebase.putObject(
  'my-bucket',
  'photo.jpg',
  stream,
  size: length,
  metadata: {'Content-Type': 'image/jpeg'},
);

For Flutter mobile uploads, the image_picker plugin gives you an XFile:

import 'package:image_picker/image_picker.dart';

final picker = ImagePicker();
final XFile? image = await picker.pickImage(source: ImageSource.gallery);

if (image != null) {
  final bytes = await image.readAsBytes();
  await filebase.putObject(
    'uploads',
    'user-${userId}/${image.name}',
    Stream.value(bytes),
    size: bytes.length,
  );
}

List objects​

final stream = filebase.listObjects('my-bucket', prefix: 'photos/');
await for (final result in stream) {
  for (final obj in result.objects) {
    print('${obj.key} ${obj.size}');
  }
}

Download an object​

import 'dart:io';

final stream = await filebase.getObject('my-bucket', 'photo.jpg');
final file = File('./downloaded.jpg');
final sink = file.openWrite();
await stream.pipe(sink);

Delete an object​

await filebase.removeObject('my-bucket', 'photo.jpg');

Pre-signed URLs​

final url = await filebase.presignedGetObject(
  'my-bucket',
  'private.pdf',
  expires: 3600,
);

print(url);

Error handling​

try {
  await filebase.statObject('my-bucket', 'maybe.jpg');
} on MinioError catch (e) {
  if (e.code == 'NoSuchKey') {
    // handle missing
  } else {
    rethrow;
  }
}

What's next​