Can't Save hasMany/belongsTo Relationship if Both Are New in Ember-Data

Question

I have two models.

App.Request = DS.Model.extend({
    materials: DS.hasMany('App.Material')
});

App.Material = DS.Model.extend({
    request: DS.belongsTo('Mat.Request')
});

In the form for creating a request, I create a new request:

App.Request.createRecord();

And bind it to the fields of the form. To create a new material, you click a button and a modal appears. When the modal appears, it creates a new material in the materials array of the request: (The material modal has its own controller, so I have to get the request by going to the RequestsNewController.)

this.get('controllers.requestsNew.materials').createRecord();

Yay! It works. I can add many materials to the request and the UI is updating to show that the associations are being created correctly. Awesome! Until... I hit the save button, calling this code from the RequestsNewController:

this.get('transaction').commit();

Now, the materials I've added to my request are torn away (the part of the template that shows the materials in the request now shows no materials.)

This is a very simplified version of my code, but the point is that everything looks good until I commit the data to the server. I have a theory as to what's happening, but I have no idea how to fix it! I'm using Rails with Active Model Serializers on my backend, by the way.

When I call commit, the Rest Adapter first POSTs to /requests. The record is added, and I get the following back from the server:

{
    "request": {
        "id": 30,
        "material_ids": []
    }
}

Yay! My request has been saved, and I now have an ID from the server.

Next, the REST Adapter POSTs to /materials and it sends the following JSON:

{
    "material": {
        "request_id": 0,
    }
}

And the server responds, giving the material an ID.

But what's this? The REST Adapter is sending request_id: 0, not request_id: 30 like it should?

Here's my theory: After the request is saved, the server responds with an empty array of material_ids. This makes sense! We haven't sent the materials to the server yet because we need the request ID first! However, when Ember Data sees an empty array of material_ids, it removes the materials from the request. Then, when the materials save, they no longer have a request, hence request_id: 0.

When I create a request with no materials, commit, add materials, commit, it works!

What am I doing wrong?

Thanks!

I am having a similar issue, could you maybe show how you can add multiple materials? I can't seem to get it to work. That would be really helpful. — Markus, Aug 01 '13 at 12:25

score 3 · Accepted Answer · answered Apr 15 '13 at 17:52

I think this is a known issue currently, and your theory is true. ATM, I have two workarounds in mind. The first one is to embed the materials in the request, by configuring the adapter like this:

DS.RESTAdapter.map('App.Request', {
  materials: {embedded: 'always'}
});

The second one would be to add an observer on the didCreate event on the request, adding the materials once created, and then commit again.

Here are the related current issues about this: https://github.com/emberjs/data/pull/440 https://github.com/emberjs/data/pull/724 https://github.com/emberjs/data/issues/437 https://github.com/emberjs/data/pull/643

score 1 · Answer 2 · answered Apr 17 '13 at 02:12

1

You may be interested in that PR https://github.com/emberjs/data/pull/876

answered Apr 17 '13 at 02:12

Cyril Fluck

1,561
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Can't Save hasMany/belongsTo Relationship if Both Are New in Ember-Data

2 Answers2