Insertion of JSON data in MongoDB

Question

I have the following JSON data to insert into my MongoDB:

[ { type: 'date',
label: 'Date Field',
className: 'form-control',
name: 'date-1500532692937' },
{ type: 'date',
label: 'Date Field',
className: 'form-control',
name: 'date-1500532693129' },
{ type: 'checkbox-group',
label: 'Checkbox Group',
name: 'checkbox-group-1500532701822',
values: [ [Object] ] } ]

The first problem is in the last entry of checkbox, the values should be

[{"label": "Option 1","value": "option-1","selected": true}]}] 

but it only tunrs out to be object, this data is coming from an AJAX call from my client end where contentType is set to application/json; charset=utf-8.

The second problem is that when I try to insert this JSON data into Mongo, i am returned with an undefined error causing only the ID to be stored and none of the JSON components.

Note: If i insert a JSON array having only one element there is no problem. i need to store all this information together as it represents a form built using a formbuilder and I want to access all of the elements together.

Any help/advice would be greatly appreciated, thank you in advance. My code is as follows:

AJAX at client end:

        $.ajax({
        type: "POST",
        contentType: "application/json; charset=utf-8",
        data: ans,
        traditional: true,
        url: "/j",
        success: function(){
            console.log('success');
        }
        });

Insertion into Mongo at server end:

 //FETCHING THE JSON OF THE CLAUSE FORM CREATED BY THE ADMIN
       router.post('/j', function(req, res, next) {

       req.session.fdata = req.body; //JSON FETCHED FROM 
                                                       JAVASCRIPT USING AJAX, STORED IN SESSION


     if(req.session.fdata==null) //CHECKING IF WE ARE RECEIVING VALUES
     {
      res.redirect('/admin');
     }
     else {

     mongo.connect(url, function (err, db) {

        assert.equal(null, err);



        db.collection('clauses').insertOne(req.session.fdata, function (err, result) {

            console.log('New Clause Added');
            console.log(req.session.fdata3);
            db.close();

        });
    });

    res.redirect('/admin');


}
//console.log(req.session.fdata);
});