feat(mdChips): Add md-on-select expression support.

Users want a way to be notified when a chip is selected.

fix #3413. closes #4088.

src/components/chips/chips.spec.js

@@ -6,6 +6,8 @@ describe('<md-chips>', function() {
     '<md-chips ng-model="items" md-on-append="appendChip($chip)"></md-chips>';
   var CHIP_REMOVE_TEMPLATE =
     '<md-chips ng-model="items" md-on-remove="removeChip($chip, $index)"></md-chips>';
+  var CHIP_SELECT_TEMPLATE =
+    '<md-chips ng-model="items" md-on-select="selectChip($chip)"></md-chips>';
   var CHIP_READONLY_AUTOCOMPLETE_TEMPLATE =
     '<md-chips ng-model="items" readonly="true">' +
     '  <md-autocomplete md-items="item in [\'hi\', \'ho\', \'he\']"></md-autocomplete>' +
@@ -134,6 +136,21 @@ describe('<md-chips>', function() {
       });
 
 
+      it('should call the select method when selecting a chip', function() {
+        var element = buildChips(CHIP_SELECT_TEMPLATE);
+        var ctrl = element.controller('mdChips');
+
+        scope.selectChip = jasmine.createSpy('selectChip');
+
+        element.scope().$apply(function() {
+          ctrl.items = ['Grape'];
+          ctrl.selectChip(0);
+        });
+
+        expect(scope.selectChip).toHaveBeenCalled();
+        expect(scope.selectChip.calls.mostRecent().args[0]).toBe('Grape');
+      });
+
       it('should handle appending an object chip', function() {
         var element = buildChips(CHIP_APPEND_TEMPLATE);
         var ctrl = element.controller('mdChips');
@@ -394,9 +411,9 @@ describe('<md-chips>', function() {
     });
   });
 
-// *******************************
-// Internal helper methods
-// *******************************
+  // *******************************
+  // Internal helper methods
+  // *******************************
 
   function buildChips(str) {
     var container;

src/components/chips/js/chipsController.js

@@ -67,11 +67,18 @@ function MdChipsCtrl ($scope, $mdConstant, $log, $element, $timeout) {
   this.chipBuffer = '';
 
   /**
-   * Whether to use the mdOnAppend expression to transform the chip buffer
+   * Whether to use the onAppend expression to transform the chip buffer
    * before appending it to the list.
    * @type {boolean}
    */
-  this.useMdOnAppend = false;
+  this.useOnAppend = false;
+
+  /**
+   * Whether to use the onSelect expression to notify the component's user
+   * after selecting a chip from the list.
+   * @type {boolean}
+   */
+  this.useOnSelect = false;
 }
 
 /**
@@ -181,8 +188,8 @@ MdChipsCtrl.prototype.getAdjacentChipIndex = function(index) {
  * @param newChip
  */
 MdChipsCtrl.prototype.appendChip = function(newChip) {
-  if (this.useMdOnAppend && this.mdOnAppend) {
-    newChip = this.mdOnAppend({'$chip': newChip});
+  if (this.useOnAppend && this.onAppend) {
+    newChip = this.onAppend({'$chip': newChip});
   }
   if (this.items.indexOf(newChip) + 1) return;
   this.items.push(newChip);
@@ -191,23 +198,34 @@ MdChipsCtrl.prototype.appendChip = function(newChip) {
 /**
  * Sets whether to use the md-on-append expression. This expression is
  * bound to scope and controller in {@code MdChipsDirective} as
- * {@code mdOnAppend}. Due to the nature of directive scope bindings, the
+ * {@code onAppend}. Due to the nature of directive scope bindings, the
  * controller cannot know on its own/from the scope whether an expression was
  * actually provided.
  */
-MdChipsCtrl.prototype.useMdOnAppendExpression = function() {
-  this.useMdOnAppend = true;
+MdChipsCtrl.prototype.useOnAppendExpression = function() {
+  this.useOnAppend = true;
 };
 
 /**
  * Sets whether to use the md-on-remove expression. This expression is
  * bound to scope and controller in {@code MdChipsDirective} as
- * {@code mdOnRemove}. Due to the nature of directive scope bindings, the
+ * {@code onRemove}. Due to the nature of directive scope bindings, the
+ * controller cannot know on its own/from the scope whether an expression was
+ * actually provided.
+ */
+MdChipsCtrl.prototype.useOnRemoveExpression = function() {
+  this.useOnRemove = true;
+};
+
+/*
+ * Sets whether to use the md-on-select expression. This expression is
+ * bound to scope and controller in {@code MdChipsDirective} as
+ * {@code onSelect}. Due to the nature of directive scope bindings, the
  * controller cannot know on its own/from the scope whether an expression was
  * actually provided.
  */
-MdChipsCtrl.prototype.useMdOnRemoveExpression = function() {
-  this.useMdOnRemove = true;
+MdChipsCtrl.prototype.useOnSelectExpression = function() {
+  this.useOnSelect = true;
 };
 
 /**
@@ -247,8 +265,8 @@ MdChipsCtrl.prototype.resetChipBuffer = function() {
 MdChipsCtrl.prototype.removeChip = function(index) {
   var removed = this.items.splice(index, 1);
 
-  if (removed && removed.length && this.useMdOnRemove && this.mdOnRemove) {
-    this.mdOnRemove({ '$chip': removed[0], '$index': index });
+  if (removed && removed.length && this.useOnRemove && this.onRemove) {
+    this.onRemove({ '$chip': removed[0], '$index': index });
   }
 };
 
@@ -280,6 +298,11 @@ MdChipsCtrl.prototype.selectAndFocusChipSafe = function(index) {
 MdChipsCtrl.prototype.selectChip = function(index) {
   if (index >= -1 && index <= this.items.length) {
     this.selectedChip = index;
+
+    // Fire the onSelect if provided
+    if (this.useOnSelect && this.onSelect) {
+      this.onSelect({'$chip': this.items[this.selectedChip] });
+    }
   } else {
     this.$log.warn('Selected Chip index out of bounds; ignoring.');
   }

src/components/chips/js/chipsDirective.js

@@ -68,6 +68,7 @@
    *    object when adding a chip.
    * @param {expression} md-on-remove An expression which will be called when a chip has been
    *    removed.
+   * @param {expression} md-on-select An expression which will be called when a chip is selected.
    * @param {string=} delete-hint A string read by screen readers instructing users that pressing
    *    the delete key will remove the chip.
    * @param {string=} delete-button-label A label for the delete button. Also hidden and read by
@@ -162,8 +163,9 @@
         readonly: '=readonly',
         placeholder: '@',
         secondaryPlaceholder: '@',
-        mdOnAppend: '&',
-        mdOnRemove: '&',
+        onAppend: '&mdOnAppend',
+        onRemove: '&mdOnRemove',
+        onSelect: '&mdOnSelect',
         deleteHint: '@',
         deleteButtonLabel: '@',
         requireMatch: '=?mdRequireMatch'
@@ -245,11 +247,15 @@
 
           // If an `md-on-append` attribute was set, tell the controller to use the expression
           // when appending chips.
-          if (attrs.mdOnAppend) mdChipsCtrl.useMdOnAppendExpression();
+          if (attrs.mdOnAppend) mdChipsCtrl.useOnAppendExpression();
 
           // If an `md-on-remove` attribute was set, tell the controller to use the expression
           // when removing chips.
-          if (attrs.mdOnRemove) mdChipsCtrl.useMdOnRemoveExpression();
+          if (attrs.mdOnRemove) mdChipsCtrl.useOnRemoveExpression();
+
+          // If an `md-on-select` attribute was set, tell the controller to use the expression
+          // when selecting chips.
+          if (attrs.mdOnSelect) mdChipsCtrl.useOnSelectExpression();
 
           // The md-autocomplete and input elements won't be compiled until after this directive
           // is complete (due to their nested nature). Wait a tick before looking for them to