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Getting started

Prerequisites​

The Dart binding wraps the Rust core via flutter_rust_bridge. You need to build the native library before running Dart code.

# From the repository root
cd bindings/dart/rust
cargo build -r
cd ..
dart pub get

The loader picks up the native library from rust/target/release/ automatically for native (non-cross-compiled) builds.

Your first program​

This program creates an in-memory storage, writes a file, reads it back, and checks metadata. It uses the memory service so there are no credentials or paths to configure.

import 'dart:typed_data';
import '../lib/opendal.dart';

void main() async {
  // Initialize storage with the memory service — no credentials needed.
  final storage = await Storage.init(schemeStr: "memory", map: {"root": "/"});

  // initFile() returns a factory function that mirrors dart:io File.
  final File = storage.initFile();

  final file = File("hello.txt");

  // Write bytes to the file.
  await file.write(Uint8List.fromList("Hello, OpenDAL!".codeUnits));

  // Read bytes back.
  final data = await file.read();
  print(String.fromCharCodes(data)); // Hello, OpenDAL!

  // Inspect metadata.
  final meta = await file.stat();
  print("isFile: ${meta.isFile}");
  print("contentLength: ${meta.contentLength}");

  // Delete the file.
  await file.delete();
}

read() returns Uint8List. write() takes Uint8List; a plain List<int> must be converted first with Uint8List.fromList(list).

meta.contentLength is typed BigInt?, not int. Use .toInt() or .toString() if you need a plain integer or a string.

Point it at a real backend​

Only Storage.init changes — the File and Directory API stays the same:

// Local filesystem rooted at /tmp
final storage = await Storage.init(schemeStr: "fs", map: {"root": "/tmp"});
final File = storage.initFile();

final file = File("test.txt");
await file.write(Uint8List.fromList("Hello from fs!".codeUnits));
print(await file.exists()); // true

For S3 or other services, pass the scheme and any configuration keys that service requires — see Services for the full list.

Sync variants​

Every async method has a blocking *Sync counterpart. Use them when you cannot await:

final storage = await Storage.init(schemeStr: "memory", map: {"root": "/"});
final File = storage.initFile();
final file = File("sync.txt");

file.writeSync(Uint8List.fromList([1, 2, 3]));
final data = file.readSync();
print(data); // [1, 2, 3]

Working with directories​

storage.initDir() returns a factory for Directory objects:

final storage = await Storage.init(schemeStr: "memory", map: {"root": "/"});
final Directory = storage.initDir();

final dir = Directory("my-dir/");
await dir.create();
print(await dir.exists()); // true

final meta = await dir.stat();
print("isDirectory: ${meta.isDirectory}"); // true