Better error responses

main.go

@@ -22,14 +22,29 @@ type Note struct {
 func httpError(err error, statusCode int, message string, w http.ResponseWriter) bool {
 	if err != nil {
 		log.Println(err)
-		w.WriteHeader(statusCode)
+		writeError(w, statusCode, message)
-		io.WriteString(w, message)
 		return true
 	}
 
 	return false
 }
 
+func writeError(w http.ResponseWriter, statusCode int, message string) {
+	type errorResponse struct {
+		Message string `json:"message"`
+	}
+
+	response := errorResponse{Message: message}
+	json, err := json.Marshal(response)
+	if err != nil {
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(statusCode)
+	w.Write(json)
+}
+
 func getNotes(w http.ResponseWriter, req *http.Request, _ httprouter.Params) {
 	res, err := db.Query(`SELECT Id, Content FROM Notes`)
 	if httpError(err, http.StatusInternalServerError, "Failed to load notes", w) {
@@ -72,8 +87,7 @@ func postNotes(w http.ResponseWriter, req *http.Request, _ httprouter.Params) {
 	}
 
 	if len(note.Content) == 0 {
-		w.WriteHeader(http.StatusBadRequest)
+		writeError(w, http.StatusBadRequest, "Missing note content")
-		io.WriteString(w, "Missing note content")
 		return
 	}
 
@@ -119,8 +133,7 @@ func getNote(w http.ResponseWriter, req *http.Request, p httprouter.Params) {
 
 	err = res.Scan(&note.Content)
 	if err == sql.ErrNoRows {
-		w.WriteHeader(http.StatusNotFound)
+		writeError(w, http.StatusNotFound, "Note doesn't exist")
-		io.WriteString(w, "Note doesn't exist")
 		return
 	}
 
@@ -155,8 +168,7 @@ func putNote(w http.ResponseWriter, req *http.Request, p httprouter.Params) {
 	}
 
 	if len(note.Content) == 0 {
-		w.WriteHeader(http.StatusBadRequest)
+		writeError(w, http.StatusBadRequest, "Missing note content")
-		io.WriteString(w, "Missing note content")
 		return
 	}
 
@@ -178,8 +190,7 @@ func putNote(w http.ResponseWriter, req *http.Request, p httprouter.Params) {
 	}
 
 	if updated == 0 {
-		w.WriteHeader(http.StatusNotFound)
+		writeError(w, http.StatusNotFound, "Note doesn't exist")
-		io.WriteString(w, "Note doesn't exist")
 		return
 	}