Ember Data - Saving record loses has many relationships

15
votes

I am having an issue working with Ember Data Fixture Adapter. When saving a record, all of the record's hasMany associations are lost. I have created a simple JS Bin to illustrate the issue: http://jsbin.com/aqiHUc/42/edit

If you edit any of the users and save, all the projects disappear.

This is using Ember 1.0.0 and the latest canary build of Ember Data.

I am not sure if I am doing something wrong or if this is an issue with Ember Data.

Thanks

4
ember.jsember-data

4 Answers

10
votes

To answer my question, the DS.JSONSerializer.serializeHasMany seems to only processes and serialize manyToNone and manyToMany relationship types. You can override this behaviour by using a custom serializer for the model:

var get = Ember.get;
App.UserSerializer = DS.RESTSerializer.extend({
  serializeHasMany: function(record, json, relationship) {
    var key = relationship.key;

    var relationshipType = DS.RelationshipChange.determineRelationshipType(record.constructor, relationship);

    if (relationshipType === 'manyToNone' || relationshipType === 'manyToMany' || relationshipType === 'manyToOne') {
      json[key] = get(record, key).mapBy('id');
    }
  }
});

Still not quite sure if this is a bug or if this is the desired/expected behaviour.

7
votes

I hit the same problem and came to the same solution. Surely this is a bug in ember-data?

Here's my solution, the only difference is that I'm modifying JSONSerializer, rather than extended RESTSerializer because I'm using the local storage adapter.:

DS.JSONSerializer.reopen({
    serializeHasMany : function(record, json, relationship) {
        var key = relationship.key;

        var relationshipType = DS.RelationshipChange.determineRelationshipType(
                record.constructor, relationship);

        if (relationshipType === 'manyToNone'
                || relationshipType === 'manyToMany'
                || relationshipType === 'manyToOne') {
            json[key] = Ember.get(record, key).mapBy('id');
            // TODO support for polymorphic manyToNone and manyToMany
            // relationships
        }
    }
});
3
votes

This is not a bug, rather a design choice in Ember Data.

The JSONSerializer.serializeHasMany method doesn't serialize manyToOne by design; typically foreign key are persisted on the belongsTo side of the relation, and the hasOne may not persist a foreign key

A work around is explained in this post: http://www.toptal.com/emberjs/a-thorough-guide-to-ember-data see the section "One-to-many and Many-to-one Relationships" the hack is To force DS.hasMany IDs to be serialized as well, you can use the Embedded Records Mixin. like so attrs: {someRelationship: {serialize: 'ids'}}

2
votes

Now DS.RelationshipChange is removed. You should use record.constructor like:

record.constructor.determineRelationshipType(relationship)

that show your relation type.