Function DefaultErrorEncoder

transport/http/server.go:190–211

DefaultErrorEncoder writes the error to the ResponseWriter, by default a content type of text/plain, a body of the plain text of the error, and a status code of 500. If the error implements Headerer, the provided headers will be applied to the response. If the error implements json.Marshaler, and th

(_ context.Context, err error, w http.ResponseWriter)

// encoded form of the error will be used. If the error implements StatusCoder,
// the provided StatusCode will be used instead of 500.
func DefaultErrorEncoder(_ context.Context, err error, w http.ResponseWriter) {
	contentType, body := "text/plain; charset=utf-8", []byte(err.Error())
	if marshaler, ok := err.(json.Marshaler); ok {
		if jsonBody, marshalErr := marshaler.MarshalJSON(); marshalErr == nil {
			contentType, body = "application/json; charset=utf-8", jsonBody
		}
	}
	w.Header().Set("Content-Type", contentType)
	if headerer, ok := err.(Headerer); ok {
		for k, values := range headerer.Headers() {
			for _, v := range values {
				w.Header().Add(k, v)
			}
		}
	}
	code := http.StatusInternalServerError
	if sc, ok := err.(StatusCoder); ok {
		code = sc.StatusCode()
	}
	w.WriteHeader(code)
	w.Write(body)
}

// StatusCoder is checked by DefaultErrorEncoder. If an error value implements
// StatusCoder, the StatusCode will be used when encoding the error. By default,