x_storage_presigned_url

A storage provider package for XStorage that supports Presigned URL-based storage services such as AWS S3 and other S3-compatible storage services.

Features

  • Abstract provider implementation for Presigned URL-based storage
  • File upload and download using Presigned URLs
  • File existence check
  • Support for AWS S3 and other S3-compatible storage services

Getting Started

Installation

Add this to your package's pubspec.yaml file:

dependencies:
  x_storage_presigned_url: ^0.0.1
  x_storage_core: ^0.0.1

Implementing the Provider

To implement your own Presigned URL storage provider, extend the PresignedUrlXStorageProvider class:

import 'package:x_storage_presigned_url/x_storage_presigned_url.dart';
import 'package:x_storage_core/x_storage_core.dart';

class MyPresignedUrlProvider extends PresignedUrlXStorageProvider {
  @override
  String get scheme => 'my_storage';

  @override
  Future<String> fetchUploadPresignedUrl({
    required List<String> dirs,
    required String filename,
  }) async {
    // Implement your logic to generate Presigned URL for upload
    // Example: Generate using AWS SDK
    return 'https://...';
  }
}

Basic Usage

// Create XStorage instance
final storage = XStorage();

// Register your custom provider
storage.registerProvider(MyPresignedUrlProvider());

// Save a file
await storage.saveFile(
  XUri.create('my_storage', 'path/to/file.txt'),
  Uint8List.fromList([/* data */]),
);

// Load a file
final data = await storage.loadFile(
  XUri.create('my_storage', 'path/to/file.txt'),
);

// Check if file exists
final exists = await storage.exists(
  XUri.create('my_storage', 'path/to/file.txt'),
);

Implementation Example

AWS S3 Implementation

import 'package:aws_s3_api/aws_s3_api.dart';

class S3PresignedUrlProvider extends PresignedUrlXStorageProvider {
  final S3Client s3Client;
  final String bucketName;

  S3PresignedUrlProvider({
    required this.s3Client,
    required this.bucketName,
  });

  @override
  String get scheme => 's3';

  @override
  Future<String> fetchUploadPresignedUrl({
    required List<String> dirs,
    required String filename,
  }) async {
    final path = [...dirs, filename].join('/');
    final url = await s3Client.getPresignedUrl(
      'PUT',
      bucketName,
      path,
      expires: Duration(minutes: 15),
    );
    return url.toString();
  }
}

Implementation Details

The PresignedUrlXStorageProvider provides the following features:

  • Network operations implementation using NetworkProviderMixin
  • saveFile: File upload using PUT request with Presigned URL
  • loadFile: File download using network URL
  • exists: File existence check using HEAD request
  • deleteFile: Currently not supported (throws UnsupportedError)

Methods that must be implemented when extending:

  • scheme: Specify the storage scheme
  • fetchUploadPresignedUrl: Generate Presigned URL for upload

Security Considerations

  • Set appropriate expiration times for Presigned URLs
  • Securely manage API keys and secrets
  • Configure proper bucket access permissions
  • Set up CORS configuration as needed
  • Use HTTPS for sensitive data transfer

Limitations

  • File deletion operation is not currently supported
  • Presigned URL generation must be handled server-side
  • Be mindful of URL expiration times

Supported Storage Services

This provider can be used with storage services that support Presigned URLs, including:

  • Amazon S3
  • Google Cloud Storage (Signed URLs)
  • Other S3-compatible storage services

Additional Information

For more information about developing packages, see the Dart guide for creating packages and the Flutter guide for developing packages and plugins.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Libraries

x_storage_presigned_url