feat: SendError helper

Author: codingconcepts

README.md

@@ -22,7 +22,7 @@ Update your existing handler signatures, by adding an `error` return type and ut
 func addProduct(w http.ResponseWriter, r *http.Request) error {
   var p product
   if err := errhandler.ParseJSON(r, &p); err != nil {
-    return fmt.Errorf("parsing request json: %w", err)
+    return SendError(w, http.StatusUnprocessableEntity, err)
   }
 
   products[p.ID] = p

errhandler.go

@@ -37,6 +37,16 @@ func SendString(w http.ResponseWriter, message string) error {
 	return nil
 }
 
+// SendError returns an error response to the caller, or fails with an error.
+func SendError(w http.ResponseWriter, code int, err error) error {
+	w.Header().Set("Content-Type", "text/plain")
+	w.WriteHeader(code)
+	if _, err := w.Write([]byte(err.Error())); err != nil {
+		return err
+	}
+	return nil
+}
+
 // ParseJSON can be used to parse a string from the body of a request.
 func ParseJSON(r *http.Request, val any) error {
 	return json.NewDecoder(r.Body).Decode(val)

errhandler_test.go

@@ -57,6 +57,14 @@ func TestWrap_ServeHTTP(t *testing.T) {
 			expectedStatus: http.StatusOK,
 			expectedBody:   "{\"a\":1}\n",
 		},
+		{
+			name: "send error",
+			handler: Wrap(func(w http.ResponseWriter, r *http.Request) error {
+				return SendError(w, http.StatusUnprocessableEntity, fmt.Errorf("error doing stuff: %w", errors.New("database error")))
+			}),
+			expectedStatus: http.StatusUnprocessableEntity,
+			expectedBody:   "error doing stuff: database error",
+		},
 		{
 			name: "error",
 			handler: Wrap(func(w http.ResponseWriter, r *http.Request) error {