apigen

apigen generates API client via execution environment such as curl.

Installation

$ go get github.com/ktr0731/apigen

Usage

This example is located under here

Generator

apigen requires *Definition which describes methods the service has.
Following definition defines CreatePost, ListPosts, GetPost, UpdatePost and DeletePost which belong to Dummy service. Request specify execution environment, apigen generates the API client and request/response types based on the execution result. ParamHint is only required when its method uses path parameters such as "/post/{postID}". apigen generates the request type by using it.

The artifact will be written to client_gen.go which is specified by apigen.WithWriter. Default output is stdout.

package main

import (
	"context"
	"log"
	"os"

	"github.com/ktr0731/apigen"
	"github.com/ktr0731/apigen/curl"
)

func main() {
	def := &apigen.Definition{
		Services: map[string][]*apigen.Method{
			"Dummy": {
				{
					Name:    "CreatePost",
					Request: curl.ParseCommand(`curl 'https://jsonplaceholder.typicode.com/posts' --data-binary '{"title":"foo","body":"bar","userId":1}'`),
				},
				{
					Name:    "ListPosts",
					Request: curl.ParseCommand(`curl https://jsonplaceholder.typicode.com/posts`),
				},
				{
					Name:    "GetPost",
					Request: curl.ParseCommand(`curl https://jsonplaceholder.typicode.com/posts?id=1`),
				},
				{
					Name:      "UpdatePost",
					Request:   curl.ParseCommand(`curl 'https://jsonplaceholder.typicode.com/posts/1' -X 'PUT' --data-binary '{"title":"foo","body":"bar","userId":1}'`),
					ParamHint: "/posts/{postID}",
				},
				{
					Name:      "DeletePost",
					Request:   curl.ParseCommand(`curl 'https://jsonplaceholder.typicode.com/posts/1' -X 'DELETE'`),
					ParamHint: "/posts/{postID}",
				},
			},
		},
	}

	f, err := os.Create("client_gen.go")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	if err := apigen.Generate(context.Background(), def, apigen.WithWriter(f)); err != nil {
		log.Fatal(err)
	}
}

The artifact is here.

Client

We can invoke the API server using the generated API client.

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log"

	"github.com/ktr0731/apigen/client"
)

func main() {
	client := NewDummyClient(client.WithInterceptors(client.ConvertStatusCodeToErrorInterceptor()))

	res, err := client.GetPost(context.Background(), &GetPostRequest{ID: "10"})
	if err != nil {
		log.Fatal(err)
	}

	b, err := json.MarshalIndent(&res, "", "  ")
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(string(b))
}

The output is:

[
  {
    "body": "quo et expedita modi cum officia vel magni\ndoloribus qui repudiandae\nvero nisi sit\nquos veniam quod sed accusamus veritatis error",
    "id": 10,
    "title": "optio molestias id quia eum",
    "userId": 1
  }
]