Custom http status code in kratos.

main.go

package main

import (
	"context"
	"log"

	"github.com/go-kratos/kratos/v2"
	"github.com/go-kratos/kratos/v2/transport/http"
)

type customStatusCode struct{}

var customStatusCodeKey = new(customStatusCode)

// mix a custom code value to ctx
func WithCustomStatusCode(ctx context.Context, code int) context.Context {
	return context.WithValue(ctx, customStatusCodeKey, code)
}

// get value from ctx
func FromCustomStatusCode(ctx context.Context) (int, bool) {
	code, ok := ctx.Value(customStatusCodeKey).(int)
	return code, ok
}

func WithHttpCode(ctx context.Context, code int) {
	if hc, ok := ctx.(http.Context); ok {
		r := hc.Request()
		ctx := r.Context()
		ctx = WithCustomStatusCode(ctx, code)
		hc.Reset(hc.Response(), r.WithContext(ctx))
	}
}

func main() {
	srv := http.NewServer(
		http.Address(":8000"),
		http.ResponseEncoder(func(w http.ResponseWriter, r *http.Request, i any) error {
			if code, ok := FromCustomStatusCode(r.Context()); ok {
				w.WriteHeader(code)
			}
			return http.DefaultResponseEncoder(w, r, i)
		}),
	)

	// your service method
	h := func(ctx context.Context) (any, error) {
		WithHttpCode(ctx, 201)

		reply := map[string]any{
			"id":   1,
			"name": "a",
		}
		return reply, nil
	}

	// simulate what happened in generated xx_http.pb.go
	srv.Route("/").GET("/a", func(ctx http.Context) error {
		reply, _ := h(ctx)
		return ctx.Result(200, reply)
	})

	k := kratos.New(kratos.Server(srv))
	if err := k.Run(); err != nil {
		log.Fatal(err)
	}

	// $ curl http://localhost:8000/a -v
	//
	// ...
	// < HTTP/1.1 201 Created
	// < Content-Type: application/json
	// ...
	// {"id":1,"name":"a"}
}