verbose logger for gin framework

logger.go

type responseWriter struct {
	gin.ResponseWriter
	buf bytes.Buffer
}

func (w *responseWriter) Write(b []byte) (int, error) {
	w.buf.Write(b)
	return w.ResponseWriter.Write(b)
}

func (w *responseWriter) Body() []byte {
	return w.buf.Bytes()
}

type requestReader struct {
	body io.ReadCloser
	buf  bytes.Buffer
}

func (r *requestReader) Read(p []byte) (int, error) {
	n, err := r.body.Read(p)
	r.buf.Write(p[0:n])
	return n, err
}

func (r *requestReader) Close() error {
	return r.body.Close()
}

func VerboseLogger(w io.Writer) gin.HandlerFunc {
	return func(c *gin.Context) {
		p := responseWriter{
			ResponseWriter: c.Writer,
		}
		c.Writer = &p
		r := requestReader{body: c.Request.Body}
		c.Request.Body = &r
		c.Next()

		if s := c.GetHeader("Content-Type"); s != "" {
			fmt.Fprintln(w, "< Content-Type:", s)
		}
		if r.buf.Len() > 0 {
			fmt.Fprintf(w, "< %s\n", r.buf.Bytes())
		}
		if s := p.Header().Get("Content-Type"); s != "" {
			fmt.Fprintln(w, "> Content-Type:", s)
		}
		if body := p.Body(); len(body) > 0 {
			fmt.Fprintf(w, "> %s\n", body)
		}
	}
}