insert values ​to a table in mongodb with nodejs - node.js

Question

I created a table in mongodb and I want to add values ​​to it via nodejs, this is my code:
mongoose.connect('mongodb://localhost:27017/attendances', { useNewUrlParser: true });
const Schema = mongoose.Schema;
const dataSchema = new Schema({ userId: String, date: Date, start: Date,end:Date });
const dataModel = mongoose.model("datas",dataSchema);
const db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function () {
console.log('connect to DB');
});
router.post('/add', (req, res) => {
const {userId,date,start} = req.body;
console.log('add',userId,date,start);
dataModel.create({userId:userId,date:date,start:start},function (err, result) {
});
dataModel.findOne({userId:userId,date:new Date().toDateString()},function(err,result){
console.log('findOne',result);
res.end(result);
})
});
He does not add my values ​​to the table.
Where's my mistake?
This is my err:
Error: datas validation failed: start: Cast to date failed for value
"11:56:26" at path "start"

Answer 1

There is a more than one mistake.
First:
Your Object Validation fails. I need to know whats inside your start variable.
Second:
You use two different dates one is date variable other one is generated by querying with date:new Date().toDateString()
Third:
Javascript works asynchronously. You cannot know when your findOne triggers after object successfully created.