Connect-Dart

Connect-Dart is a slim library for using generated, type-safe, and idiomatic Dart clients to communicate with your app's servers using Protocol Buffers (Protobuf). It works with the Connect, gRPC, and gRPC-Web protocol.

Given a simple Protobuf schema, Connect-Dart generates idiomatic dart:

Click to expand eliza.connect.client.dart

import "package:connectrpc/connect.dart" as connect;
import "eliza.pb.dart" as connectrpcelizav1eliza;
import "eliza.connect.spec.dart" as specs;

extension type ElizaServiceClient(connect.Transport _transport) {
  Future<connectrpcelizav1eliza.SayResponse> say(
    connectrpcelizav1eliza.SayRequest input, {
    connect.Headers? headers,
    connect.AbortSignal? signal,
    Function(connect.Headers)? onHeader,
    Function(connect.Headers)? onTrailer,
  }) {
    return connect.Client(_transport).unary(
      specs.ElizaService.say,
      input,
      signal: signal,
      headers: headers,
      onHeader: onHeader,
      onTrailer: onTrailer,
    );
  }

  Stream<connectrpcelizav1eliza.ConverseResponse> converse(
    Stream<connectrpcelizav1eliza.ConverseRequest> input, {
    connect.Headers? headers,
    connect.AbortSignal? signal,
    Function(connect.Headers)? onHeader,
    Function(connect.Headers)? onTrailer,
  }) {
    return connect.Client(_transport).bidi(
      specs.ElizaService.converse,
      input,
      signal: signal,
      headers: headers,
      onHeader: onHeader,
      onTrailer: onTrailer,
    );
  }

  Stream<connectrpcelizav1eliza.IntroduceResponse> introduce(
    connectrpcelizav1eliza.IntroduceRequest input, {
    connect.Headers? headers,
    connect.AbortSignal? signal,
    Function(connect.Headers)? onHeader,
    Function(connect.Headers)? onTrailer,
  }) {
    return connect.Client(_transport).server(
      specs.ElizaService.introduce,
      input,
      signal: signal,
      headers: headers,
      onHeader: onHeader,
      onTrailer: onTrailer,
    );
  }
}

This code can then be integrated with just a few lines:

void main() async {
    late ElizaServiceClient elizaClient;
    final response = await elizaClient.say(SayRequest(sentence: "Hey!"))
    print(response.message);
}

That’s it! You no longer need to manually define request/response models, write encode/decode methods, specify the exact path of your request, nor worry about the underlying networking transport for your applications!

Quick Start

Head over to our quick start tutorial to get started. It only takes ~10 minutes to complete a working chat app that uses Connect-Dart!

Documentation

Comprehensive documentation for everything, including interceptors, streaming, and error handling is available on the connectrpc.com website.

Generation Options

Option	Type	Default	Details
keep_empty_files	Boolean	false	Generate files even if the proto file doesn't have any service definitions

Example Apps

Example apps are available in /example.

Contributing

We'd love your help making Connect better!

Extensive instructions for building the library and generator plugins locally, running tests, and contributing to the repository are available in our CONTRIBUTING.md guide. Please check it out for details.

Ecosystem

• connect-swift: Swift clients for idiomatic gRPC & Connect RPC
• connect-kotlin: Idiomatic gRPC & Connect RPCs for Kotlin
• connect-es: Type-safe APIs with Protobuf and TypeScript.
• connect-go: Service handlers and clients for GoLang
• conformance: Connect, gRPC, and gRPC-Web interoperability tests

Status

This project is stable and follows semantic versioning, which means any breaking changes will result in a major version increase. Our goal is to not make breaking changes unless absolutely necessary.

Legal

Offered under the Apache 2 license.