Implement filterBy on DS.ManyArray

packages/ember-data/lib/system/many-array.js

@@ -2,6 +2,7 @@
   @module ember-data
 */
 import { PromiseArray } from "ember-data/system/promise-proxies";
+import FilteredSubset from "ember-data/system/record-arrays/filtered-subset";
 
 var get = Ember.get;
 var set = Ember.set;
@@ -277,5 +278,37 @@ export default Ember.Object.extend(Ember.MutableArray, Ember.Evented, {
     this.pushObject(record);
 
     return record;
+  },
+
+  /**
+    Get a filtered subset of the underlying `ManyArray`.
+    The subset updates when a record would match or mismatch the
+    specified filter parameters.
+
+    Example
+
+    ```javascript
+    var post = store.peekRecord('post', 1)
+    // All the comments that are deleted locally but not yet saved to the server.
+    var deletedComments = post.get('comments').filterBy('isDeleted');
+    ```
+
+    @method filterBy
+    @param {String} key property path
+    @param {*} value optional
+
+  */
+  filterBy: function(key, value) {
+    // only pass value to the arguments if it is present; this mimics the same
+    // behavior for `filterBy`: http://git.io/vIurH
+    var filterByArgs = [key];
+    if (arguments.length === 2) {
+      filterByArgs.push(value);
+    }
+
+    return FilteredSubset.create({
+      filterByArgs,
+      recordArray: this
+    });
   }
 });

packages/ember-data/lib/system/record-arrays/filtered-subset.js

@@ -0,0 +1,15 @@
+var FilteredSubset = Ember.ArrayProxy.extend({
+  init: function() {
+    this._super(...arguments);
+
+    var { filterByArgs, recordArray } = this.getProperties('filterByArgs', 'recordArray');
+    var [key] = filterByArgs;
+
+    var path = `recordArray.@each.${key}`;
+    Ember.defineProperty(this, 'content', Ember.computed(path, function() {
+      return this.filterBy.apply(recordArray, filterByArgs);
+    }));
+  }
+});
+
+export default FilteredSubset;

packages/ember-data/lib/system/record-arrays/record-array.js

@@ -4,25 +4,11 @@
 
 import { PromiseArray } from "ember-data/system/promise-proxies";
 import SnapshotRecordArray from "ember-data/system/snapshot-record-array";
+import FilteredSubset from "ember-data/system/record-arrays/filtered-subset";
 
 var get = Ember.get;
 var set = Ember.set;
 
-var FilteredSubset = Ember.ArrayProxy.extend({
-  init: function() {
-    this._super(...arguments);
-
-    var { filterByArgs, recordArray } = this.getProperties('filterByArgs', 'recordArray');
-    var [key] = filterByArgs;
-
-    var path = `recordArray.@each.${key}`;
-    Ember.defineProperty(this, 'content', Ember.computed(path, function() {
-      return this.filterBy.apply(recordArray, filterByArgs);
-    }));
-  }
-});
-
-
 /**
   A record array is an array that contains records of a certain type. The record
   array materializes records as needed when they are retrieved for the first

packages/ember-data/tests/integration/relationships/has-many-test.js

@@ -2340,3 +2340,75 @@ test("metadata should be reset between requests", function() {
     });
   });
 });
+
+
+test("filterBy - returns a filtered subset", function () {
+  var chapter, page;
+  run(function() {
+    env.store.push({
+      data: {
+        type: 'chapter',
+        id: '1',
+        relationships: {
+          pages: {
+            data: [
+              { type: 'page', id: '2' },
+              { type: 'page', id: '3' }
+            ]
+          }
+        }
+      },
+      included: [{
+        type: 'page',
+        id: '2'
+      }, {
+        type: 'page',
+        id: '3'
+      }]
+    });
+    chapter = env.store.peekRecord('chapter', 1);
+    page = env.store.peekRecord('page', 2);
+  });
+  run(function() {
+    page.deleteRecord();
+  });
+  run(function() {
+    equal(chapter.get('pages').filterBy('isDeleted').get('length'), 1, "Can filter by deleted records");
+  });
+});
+
+
+test("filterBy - returns a filtered subset", function () {
+  var chapter;
+  run(function() {
+    env.store.push({
+      data: {
+        type: 'chapter',
+        id: '1',
+        relationships: {
+          pages: {
+            data: [
+              { type: 'page', id: '2' },
+              { type: 'page', id: '3' }
+            ]
+          }
+        }
+      },
+      included: [{
+        type: 'page',
+        id: '2'
+      }, {
+        type: 'page',
+        id: '3'
+      }]
+    });
+    chapter = env.store.peekRecord('chapter', 1);
+  });
+  run(function() {
+    env.store.peekRecord('page', 2).deleteRecord();
+    var deletedChapters = chapter.get('pages').filterBy('isDeleted');
+    equal(deletedChapters.get('length'), 1);
+    env.store.peekRecord('page', 3).deleteRecord();
+    equal(deletedChapters.get('length'), 2);
+  });
+});