fix(mdChips): Run duplicate check after mdOnAppend.

The duplicate check was firing before the user's onAppend
method had a chance to run, so the check would always
compare a string against an object and fail.

fixes angular#2748. closes angular#4113.

src/components/chips/chips.spec.js

@@ -135,6 +135,30 @@ describe('<md-chips>', function() {
         expect(scope.items[3].name).toBe('Grape');
         expect(scope.items[3].uppername).toBe('GRAPE');
       });
+
+      it('should disallow duplicate object chips', function() {
+        var element = buildChips(CHIP_APPEND_TEMPLATE);
+        var ctrl = element.controller('mdChips');
+
+        // Manually set the items
+        ctrl.items = [{name: 'Apple', uppername: 'APPLE'}];
+
+        // Make our custom appendChip function return our existing item
+        var chipObj = function(chip) {
+          return ctrl.items[0];
+        };
+
+        scope.appendChip = jasmine.createSpy('appendChip').and.callFake(chipObj);
+
+        element.scope().$apply(function() {
+          ctrl.chipBuffer = 'Apple';
+          simulateInputEnterKey(ctrl);
+        });
+
+        expect(ctrl.items.length).toBe(1);
+        expect(scope.appendChip).toHaveBeenCalled();
+        expect(scope.appendChip.calls.mostRecent().args[0]).toBe('Apple');
+      });
     });
 
     describe('custom inputs', function() {
@@ -309,9 +333,9 @@ describe('<md-chips>', function() {
     });
   });
 
-  // *******************************
-  // Internal helper methods
-  // *******************************
+// *******************************
+// Internal helper methods
+// *******************************
 
   function buildChips(str) {
     var container;

src/components/chips/js/chipsController.js

@@ -181,10 +181,10 @@ MdChipsCtrl.prototype.getAdjacentChipIndex = function(index) {
  * @param newChip
  */
 MdChipsCtrl.prototype.appendChip = function(newChip) {
-  if (this.items.indexOf(newChip) + 1) return;
   if (this.useMdOnAppend && this.mdOnAppend) {
     newChip = this.mdOnAppend({'$chip': newChip});
   }
+  if (this.items.indexOf(newChip) + 1) return;
   this.items.push(newChip);
 };