How to add parent object to child in a one-to-may relationship in ember js

I have two models in ember.js with a one-to-may relationship. Now I want to create a new child object and need to assign an associated parent object. I can't figure out how to do this. My models are defined with the following code:

model of parent-object

import DS from 'ember-data';

export default DS.Model.extend({
    name: DS.attr('string'),
    children: DS.hasMany('child')
});

model of child-object

import DS from 'ember-data';

export default DS.Model.extend({
    name: DS.attr('string'),
    parent: DS.belongsTo('parent')
});

In the model()-method of the route create a child object.

var child = this.store.createRecord('child');

and then query for the parent-object.

var parent = this.findRecord('parent', 2);

Then I tried to bind them together but anythig I tried failed. For example:

parent.get('child').addObject(child) // or
parent.get('child').pushObject(child) // or
child.set('parent', parent)

These things result in parent not having anything in child and child not having anything in parent. I also did some attempts with async promise resolving but with no success. It would be great if someone could post an example how to manage this.

Solution

Basically this works as you expect. But you have a few minor errors:

Sometimes you use child and sometimes child-object. Same goes for parent.
findRecord returns a PromiseObject. You probably want to wait for the promise to resolve.
Its not addObject.

Also you can do it from both sides. Either set the parent:

this.store.findRecord('parent-object', 2).then(parent => {
  const child = this.store.createRecord('child-object');
  child.set('parent', parent);
});

Or you add the child to the children:

this.store.findRecord('parent-object', 2).then(parent => {
  const child = this.store.createRecord('child-object');
  parent.get('children').pushObject(child);
});

Maybe check out this twiddle.