Starting to add feedback in the registration (fixes #78)

backend/src/app.py

@@ -144,16 +144,26 @@ def register():
     req = flask.request.get_json(force=True)
     username = req.get('username', None)
     password = req.get('password', None)
-    new_user = User(
-        username=username,
-        password=guard.hash_password(password)
-    )
-    db.session.add(new_user)
-    db.session.commit()
-    ret = {'message': 'Account erstellt für den Account {}'.format(
-        new_user.username
-    )}
-    return ret, 200
+
+    get_list_by_username = User.query.filter_by(username=username).first()
+    print(get_list_by_username)
+    if get_list_by_username is None:
+        new_user = User(
+            username=username,
+            password=guard.hash_password(password)
+        )
+        db.session.add(new_user)
+        db.session.commit()
+        ret = {'message': 'Account erstellt für den Account {}'.format(
+            new_user.username
+        )}
+        return ret, 200
+    else:
+        ret = {'message': 'Benutzername {} existiert bereits. Bitte wähle einen anderen '.format(
+            username
+        )}
+        return ret, 409
+
 
 
 @app.route('/umfrage', methods=['POST'])