Ember Data Store.createRecord().save() posting and empty object

I am trying to make a post request using Ember Data and using JSON server in the backend.

I can see a POST /results 201 0.847 ms - 23 in console but in actual JSON file it's just an empty object with just id

{"id": "rkU3UcPRW"}

My Model looks like

import DS from 'ember-data';

export default DS.Model.extend({
    quizAttemped: DS.attr('string'),
    quizId: DS.attr('string'),
    timeAttempedAt: DS.attr('string'),
    result: DS.attr(),
    attempedBy: DS.attr('string'),
    postedBy: DS.attr('string')});

My Adapter Looks like

import DS from 'ember-data';

export default DS.JSONAPIAdapter.extend({
namespace: '',
host: 'http://localhost:3000',
headers: function() {
    var headers = {};
    headers['Content-Type'] = 'application/vnd.api+json';
    return headers;
},
save: function() {
    return this._super();
}});

Serializer

import DS from 'ember-data';
export default DS.JSONSerializer.extend({});

And i am calling

postResults() {
    let store = this.get('store');
    const quizId = this.get('evaluatingQuizId');
    store.find('quiz', quizId).then((data) => {
        store.createRecord('result', {
            quizAttemped: data.data.topic,
            quizId: quizId,
            timeAttempedAt: new Date().getTime(),
            result: this.get('resultArray'),
            attempedBy: this.get('userInsession.emailId'),
            postedBy: data.data.postedBy
        }).save();
    });
}