在Ember数据中，在两个对象之间形成关联的最佳方法是什么？

Question

Let's say some DS.Model class Leaf belongsTo class Tree , and one Tree hasMany leaves , ie:

App.Leaf = DS.Model.extend({

    tree:   DS.belongsTo('App.Tree'),

});

App.Tree = DS.Model.extend({

    leaves:   DS.hasMany('App.Leaf'),

})

So far I'm manually manipulating Tree 's leaves field:

tree = App.store.create( App.Tree )
leaf = App.store.create( App.Leaf )
tree.get('leaves').pushObject( leaf )
App.store.commit()

Now this appears to work but then things get weird:

when I check leaf's tree field, I see a App.Tree instance is in there and the id matchs that of tree:

leaf.get('tree').get('id')  // outputs 1
tree.get('id')             // outputs 1

So far ok. Now I check tree's leaves field, which I presume is an Ember mutable-array, and I see this:

branch.get('leaves').content  // outputs [ 2 ]
leaf.get('id')                // outputs 1

So I presume the leaves mutable-array is storing an array of leaf ids, except its id does not match that of the leaf instance.

Note when the leaf's id is 2, it's stored in the branch.leaves.content field as 4, if leaf id is 3, the stored id is 6, etc.

Answer 1

Everything is working properly in your example, accessing the content variable branch.get('leaves') record array returns an array of the clientId 's of the objects.

However that is the exception as accessing properties any other way will transparently accesses the objects themselves.

In your case if you want ID's use branch.get('leaves').mapProperty('id')