Improve mixin of view ui hash to behaviors

This commit makes the view ui hash available consistently in
Behaviors, making it available in callbacks as well as the
events and triggers hashes.  There is also some refactoring to simplify
and centralize how the views ui hash is mixed into the Behaviors
reducing duplication

docs/marionette.behavior.md

@@ -273,3 +273,21 @@ Marionette.Behavior.extend({
 	}
 });
 ```
+
+### ui
+
+Behaviors can have their own ui hash, which will be mixed into the ui hash of its associated view instance.
+ui elements defined on either the behavior or the view will be made available within events, and triggers.  They
+also are attached directly to the behavior and can be accessed within behavior methods as `this.ui`.
+
+```js
+Marionette.Behavior.extend({
+    ui: {
+        'foo' : 'li.foo'
+    },
+
+    doStuff: function() {
+        this.ui.foo.trigger('something');
+    }
+})
+```

src/behavior.js

@@ -15,6 +15,12 @@ Marionette.Behavior = Marionette.Object.extend({
     this.view = view;
     this.defaults = _.result(this, 'defaults') || {};
     this.options  = _.extend({}, this.defaults, options);
+    // Construct an internal UI hash using
+    // the views UI hash and then the behaviors UI hash.
+    // This allows the user to use UI hash elements
+    // defined in the parent view as well as those
+    // defined in the given behavior.
+    this.ui = _.extend({}, _.result(view, 'ui'), _.result(this, 'ui'));
 
     Marionette.Object.apply(this, arguments);
   },

src/behaviors.js

@@ -37,23 +37,15 @@ Marionette.Behaviors = (function(Marionette, _) {
 
     behaviorEvents: function(behaviorEvents, behaviors) {
       var _behaviorsEvents = {};
-      var viewUI = this._uiBindings || _.result(this, 'ui');
 
       _.each(behaviors, function(b, i) {
         var _events = {};
         var behaviorEvents = _.clone(_.result(b, 'events')) || {};
-        var behaviorUI = b._uiBindings || _.result(b, 'ui');
 
-        // Construct an internal UI hash first using
-        // the views UI hash and then the behaviors UI hash.
-        // This allows the user to use UI hash elements
-        // defined in the parent view as well as those
-        // defined in the given behavior.
-        var ui = _.extend({}, viewUI, behaviorUI);
 
         // Normalize behavior events hash to allow
         // a user to use the @ui. syntax.
-        behaviorEvents = Marionette.normalizeUIKeys(behaviorEvents, ui);
+        behaviorEvents = Marionette.normalizeUIKeys(behaviorEvents, getBehaviorsUI(b));
 
         var j = 0;
         _.each(behaviorEvents, function(behaviour, key) {
@@ -140,7 +132,6 @@ Marionette.Behaviors = (function(Marionette, _) {
   // for views
   function BehaviorTriggersBuilder(view, behaviors) {
     this._view      = view;
-    this._viewUI    = _.result(view, 'ui');
     this._behaviors = behaviors;
     this._triggers  = {};
   }
@@ -154,10 +145,9 @@ Marionette.Behaviors = (function(Marionette, _) {
 
     // Internal method to build all trigger handlers for a given behavior
     _buildTriggerHandlersForBehavior: function(behavior, i) {
-      var ui = _.extend({}, this._viewUI, _.result(behavior, 'ui'));
       var triggersHash = _.clone(_.result(behavior, 'triggers')) || {};
 
-      triggersHash = Marionette.normalizeUIKeys(triggersHash, ui);
+      triggersHash = Marionette.normalizeUIKeys(triggersHash, getBehaviorsUI(behavior));
 
       _.each(triggersHash, _.bind(this._setHandlerForBehavior, this, behavior, i));
     },
@@ -174,6 +164,10 @@ Marionette.Behaviors = (function(Marionette, _) {
     }
   });
 
+  function getBehaviorsUI(behavior) {
+    return behavior._uiBindings || behavior.ui;
+  }
+
   return Behaviors;
 
 })(Marionette, _);

test/unit/behaviors.spec.js

@@ -276,6 +276,9 @@ describe('Behaviors', function() {
             'click @ui.foo': 'onFooClick',
             'click @ui.bar': 'onBarClick'
           },
+
+          testViewUI: function() { this.ui.bar.trigger('test'); },
+          testBehaviorUI: function() { this.ui.foo.trigger('test'); },
           onRender     : this.onRenderStub,
           onBeforeShow : this.onBeforeShowStub,
           onShow       : this.onShowStub,
@@ -344,6 +347,14 @@ describe('Behaviors', function() {
         expect(this.onRenderStub).to.have.been.calledOnce;
       });
 
+      it('should make the view\'s ui hash available to callbacks', function() {
+        expect(this.fooBehavior.testViewUI.bind(this.fooBehavior)).to.not.throw(Error);
+      });
+
+      it('should make the behavior\'s ui hash available to callbacks', function() {
+        expect(this.fooBehavior.testBehaviorUI.bind(this.fooBehavior)).to.not.throw(Error);
+      });
+
       describe("the $el", function() {
         beforeEach(function() {
           this.view.$el.find('.foo').click();