seanpfeifer / twirp-gen

Protobuf client code generators for Twirp services (https://github.com/twitchtv/twirp)

twirp-gen

Simple Protobuf code generators specifically for Twirp services.

This exists because other code generators either required external dependencies or were too complex for my needs.

Installing

# For TypeScript generation
go install github.com/seanpfeifer/twirp-gen/cmd/protoc-gen-twirpts@latest

# For C# generation
go install github.com/seanpfeifer/twirp-gen/cmd/protoc-gen-twirpcs@latest

# For JavaScript generation
go install github.com/seanpfeifer/twirp-gen/cmd/protoc-gen-twirpjs@latest

Ensure your ~/go/bin (Linux) or %USERPROFILE%/go/bin (Windows) are on your PATH.

Usage

# Typical Twirp usage to generate methods from the "examples" dir into "./examples_gen/generated.js"
# For TypeScript
protoc -I ./examples --twirpts_out=./examples_gen/ ./examples/*.proto
# For JavaScript
protoc -I ./examples --twirpjs_out=./examples_gen/ ./examples/*.proto

# If you use twirp.WithServerPathPrefix(), eg `twirp.WithServerPathPrefix("/rpc")`, you can specify the
# prefix with the "pathPrefix" flag
protoc -I ./examples --twirpjs_out=pathPrefix=/rpc:./examples_gen/ ./examples/*.proto

# C# is the same as above two examples, but uses `--twirpcs_out`
protoc -I ./examples --twirpcs_out=./examples_gen/ ./examples/*.proto
protoc -I ./examples --twirpcs_out=pathPrefix=/rpc:./examples_gen/ ./examples/*.proto

# For TypeScript, you can also add `protoCase=true` to generate field names in the same case as the proto file
protoc -I ./examples --twirpts_out=pathPrefix=/rpc,protoCase=true:./examples_gen/ ./examples/*.proto

Generator Options

Option	Language	Description
pathPrefix	TypeScript, JavaScript, C#	The path prefix to use for the Twirp service. This is useful if you use twirp.WithServerPathPrefix().
protoCase	TypeScript	If true, field names will be generated in the same case as the proto file. If false, field names will be generated in camelCase. This is useful if you DO NOT use twirp.WithServerJSONCamelCaseNames().

TypeScript

This is an extremely simple generator for TypeScript, which communicates with JSON only. Assumptions:

• You are OK with the fetch() browser API
  • That is, you don't need to worry about older browsers that may not support it
• Uses camelCase fields by default (ie, you have the option twirp.WithServerJSONCamelCaseNames(true) set)
  • If you don't want fields changed to camelCase, use protoCase=true in your twirpts_out options, eg if you want to use the same case as the proto file and to also generate with the path prefix /rpc:
    • --twirpts_out=pathPrefix=/rpc,protoCase=true:./

C#

This is an extremely simple generator for C#. This client makes requests using binary serialized Protobuf.

On error, the generated functions will throw a GeneratedAPI.Exception.

JavaScript

Another extremely simple generator, but for JavaScript, which communicates with JSON only. It makes a few assumptions to keep things simple:

• Your Twirp server has the option twirp.WithServerJSONCamelCaseNames(true) set
  • This client uses proto3 JSON serialization instead of the snake-case default in Twirp
• You are OK with the fetch() browser API
  • That is, you don't need to worry about older browsers that may not support it

Unity Example

Note that this example does not deal with errors. It is just a simple example of how to call the generated functions.

using System.Net.Http;
using UnityEngine;
using Google.Protobuf; // For ByteString in this example

public class APICaller : MonoBehaviour {
  public const string SERVER_ADDRESS = "http://localhost:8080/";

  static readonly HttpClient client = new HttpClient();
  static APICaller() {
    client.BaseAddress = new System.Uri(SERVER_ADDRESS);
    client.DefaultRequestHeaders.Accept.Add(GeneratedAPI.CONTENT_TYPE_PROTOBUF);
  }

  // Start is called before the first frame update
  async void Start() {
    var checkoutResult = await GeneratedAPI.CreateCheckoutSession(client, new Shop.CheckoutRequest { ItemId = "item_cool_stuff" });
    Debug.Log(checkoutResult);

    var logoutResult = await GeneratedAPI.Logout(client, new Account.LogoutRequest { AccountId = 42, Token = ByteString.CopyFrom(new byte[]{1,2,3,4,5}) });
    Debug.Log(logoutResult);
  }
}