pingcap/fn

fn's Issues

Support for more custom request parsers

Here is my implementation

package main

import (
	"context"
	"net/http"
	"net/url"

	"github.com/pingcap/fn"
)
func main() {
	// Use reflection out(0) resp injection new request parser
	fn.SetRequestPlugin(func(ctx context.Context, r *http.Request) (url.Values, error) {
		return r.URL.Query(), nil
	})
	server := &http.Server{
		Addr:    ":8080",
		Handler: fn.Wrap(func (query url.Values) (string, error) {
			return query.Get("params"), nil
		}),
	}
	server.ListenAndServe()
}

Improve the test coverage

• wrapper.go
• adatper.go
• group.go
• interface.go
• plugin.go
• form_helper.go
• types.go

unhandled error unpacking

demo:

package main

import (
	"context"
	"net/http"

	"github.com/gorilla/mux"
	"github.com/pingcap/fn"
	"github.com/pkg/errors"
)

var (
	// ErrTest define an error
	ErrTest = errors.New("test")
	errs    = map[error]int{
		ErrTest: 1001,
	}
)

// Unknown default error code
const Unknown = 1000

type statusCodeError struct {
	err        error
	statusCode int
}

func (s *statusCodeError) StatusCode() int {
	return s.statusCode
}

func (s *statusCodeError) Error() string {
	return s.err.Error()
}

func (s *statusCodeError) Unwrap() error {
	return s.err
}

// ErrorWithStatusCode Rewrite
func ErrorWithStatusCode(err error, statusCode int) error {
	return &statusCodeError{err, statusCode}
}

// Error1 fn.ErrorWithStatusCode wrapped error cannot be unpacked to the original error
func Error1() (string, error) {
	return "", fn.ErrorWithStatusCode(errors.WithStack(ErrTest), 500)
}

// Error2 ErrorWithStatusCode rewrite and implement the `StatusCode`, `Unwrap` interface to support the original error
func Error2() (string, error) {
	return "", ErrorWithStatusCode(errors.WithStack(ErrTest), 500)
}

// Error3 The ErrorWithStatusCode error can no longer be set with a status code if it is wrapped.
func Error3() (string, error) {
	return "", errors.WithStack(ErrorWithStatusCode(ErrTest, 500))
}

// Code 通过 error 获取 code 定义
func Code(err error) int {
	code, ok := errs[err]
	if !ok {
		for err != nil {
			err = errors.Unwrap(err)
			code, ok = errs[err]
			if ok {
				return code
			}
		}
		code = Unknown
	}
	return code
}

func main() {
	// generate a response with a status code via error
	fn.SetErrorEncoder(func(ctx context.Context, err error) interface{} {
		code := Code(err)
		return map[string]interface{}{
			"code":    code,
			"message": err.Error(),
		}
	})
	router := mux.NewRouter()
	router.Handle("/error1", fn.Wrap(Error1))
	router.Handle("/error2", fn.Wrap(Error2))
	router.Handle("/error3", fn.Wrap(Error3))
	server := &http.Server{
		Addr:    ":8080",
		Handler: router,
	}
	server.ListenAndServe()
}

run server

go run main.go

test response

$ curl -i http://127.0.0.1:8080/error1
HTTP/1.1 500 Internal Server Error
Content-Type: application/json; charset=utf-8
Date: Thu, 27 Feb 2020 09:39:56 GMT
Content-Length: 31

{"code":1000,"message":"test"}

$ curl -i http://127.0.0.1:8080/error2
HTTP/1.1 500 Internal Server Error
Content-Type: application/json; charset=utf-8
Date: Thu, 27 Feb 2020 09:40:04 GMT
Content-Length: 31

{"code":1001,"message":"test"}

$curl -i http://127.0.0.1:8080/error3
HTTP/1.1 400 Bad Request
Content-Type: application/json; charset=utf-8
Date: Thu, 27 Feb 2020 09:40:11 GMT
Content-Length: 31

{"code":1001,"message":"test"}

If possible I can submit a merge request to fix these issues