update PUT /todos/:id to use sequelize

server.js

@@ -108,32 +108,31 @@ app.put('/todos/:id', (req, res) => {
       "error": "id is in incorrect format"
     });
   } else {
-    var matchesTodo = _.findWhere(todos, {
-      id: todoId
-    });
-    if (!matchesTodo) {
-      res.status(404).json({
-        "error": "no todo found with that id"
-      });
-    }
 
     var body = _.pick(req.body, 'description', 'completed');
-    var validAttributes = {};
+    var attributes = {};
 
-    if (body.hasOwnProperty('completed') && _.isBoolean(body.completed)) {
-      validAttributes.completed = body.completed;
-    } else if (body.hasOwnProperty('completed')) {
-      return res.status(400).send();
+    if (body.hasOwnProperty('completed')) {
+      attributes.completed = body.completed;
     }
 
-    if (body.hasOwnProperty('description') && _.isString(body.description) && body.description.trim().length !== 0) {
-      validAttributes.description = body.description;
-    } else if (body.hasOwnProperty('description')) {
-      return res.status(400).send();
+    if (body.hasOwnProperty('description')) {
+      attributes.description = body.description;
     }
 
-    _.extend(matchesTodo, validAttributes);
-    res.json(matchesTodo);
+    db.todo.findById(todoId).then( (todo) => {
+      if (todo) {
+        todo.update(attributes).then( (todo) => {
+          res.json(todo);
+        }, (e) => {
+          res.status(400).json(e);
+        });
+      } else {
+        res.status(404).send();
+      }
+    }, () => {
+      res.status(500).send();
+    });
   }
 });