gistfile1.txt

var Node = Ember.extend({
	datasource: null,
	links: Ember.computed(function () {
		var ds = this.get('datasource');
		if (ds) return ds.linksForNode(this.get('id));
		return [];
	}).property()
});

var Link = Ember.extend({});

var node1 = Node.create({id: 1, name: "node 1"});
var node2 = Node.create({id: 2, name: "node 2"});
var node3 = Node.create({id: 3, name: "node 3"});

var link1 = Link.create({left_node: 1, right_node: 2});
var link2 = Link.create({left_node: 1, right_node: 3});

var datasource = Ember.Object.create({
	nodes: [node1, node2, node3],
	links: [link1, link2],

	linksForNode: function (node_id) {
		var links = this.get('links', function (item) {
			return item.get('left_node') == node_id || item.get('right_node') == node_id
		});
		return links;
	}
});

node1.set('datasource', datasource);

node1.get('links') => [link1, link2];

node2.set('datasource', datasource);

node2.get('links') => [link1];

node3.set('datasource', datasource);

node3.get('links') => [link2];