Add spec about $rawData value in extended context when binding to a f…

…unction that returns an observable view model.
haru01 · Feb 9, 2014 · f5832fd · f5832fd
1 parent ea06bdd
commit f5832fd
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Showing 2 changed files with 36 additions and 2 deletions.
diff --git a/spec/bindingDependencyBehaviors.js b/spec/bindingDependencyBehaviors.js
@@ -342,7 +342,7 @@ describe('Binding dependencies', function() {
 
         it('Should update all extended contexts (including values copied from the parent)', function() {
             ko.bindingHandlers.withProperties = {
-                init: function(element, valueAccessor, allBindingsAccessor, viewModel, bindingContext) {
+                init: function(element, valueAccessor, allBindings, viewModel, bindingContext) {
                     var innerBindingContext = bindingContext.extend(valueAccessor);
                     ko.applyBindingsToDescendants(innerBindingContext, element);
                     return { controlsDescendantBindings : true };
@@ -368,9 +368,41 @@ describe('Binding dependencies', function() {
             expect(vm.getSubscriptionsCount()).toEqual(0);
         });
 
+        it('Should maintain correct $rawData in extended context when parent is bound to a function that returns an observable view model', function() {
+            ko.bindingHandlers.extended = {
+                init: function(element, valueAccessor, allBindings, viewModel, bindingContext) {
+                    ko.applyBindingsToDescendants(bindingContext.extend(valueAccessor), element);
+                    return { controlsDescendantBindings : true };
+                }
+            };
+
+            var vm1 = ko.observable('vm1'),
+                vm2 = ko.observable('vm2'),
+                whichVm = ko.observable(vm1);
+            testNode.innerHTML = "<div data-bind='extended: {}'><div data-bind='text: $data'></div></div>";
+            ko.applyBindings(function() { return whichVm(); }, testNode);
+            expect(testNode).toContainText('vm1');
+
+            var parentContext = ko.contextFor(testNode),
+                childContext = ko.contextFor(testNode.childNodes[0].childNodes[0]);
+
+            expect(parentContext.$data).toEqual('vm1');
+            expect(parentContext.$rawData).toBe(vm1);
+
+            expect(childContext).not.toBe(parentContext);
+            expect(childContext.$data).toEqual('vm1');
+            expect(childContext.$rawData).toBe(vm1);
+
+            // Updating view model updates bindings and context
+            whichVm(vm2);
+            expect(testNode).toContainText('vm2');
+            expect(childContext.$data).toEqual('vm2');
+            expect(childContext.$rawData).toBe(vm2);
+        });
+
         it('Should update an extended child context', function() {
             ko.bindingHandlers.withProperties = {
-                init: function(element, valueAccessor, allBindingsAccessor, viewModel, bindingContext) {
+                init: function(element, valueAccessor, allBindings, viewModel, bindingContext) {
                     var childBindingContext = bindingContext.createChildContext(null, null, function(context) {
                         ko.utils.extend(context, valueAccessor());
                     });

diff --git a/src/binding/bindingAttributeSyntax.js b/src/binding/bindingAttributeSyntax.js
@@ -126,6 +126,8 @@
     // Similarly to "child" contexts, provide a function here to make sure that the correct values are set
     // when an observable view model is updated.
     ko.bindingContext.prototype['extend'] = function(properties) {
+        // If the parent context references an observable view model, "_subscribable" will always be the
+        // latest view model object. If not, "_subscribable" isn't set, and we can use the static "$data" value.
         return new ko.bindingContext(this._subscribable || this['$data'], this, null, function(self, parentContext) {
             // This "child" context doesn't directly track a parent observable view model,
             // so we need to manually set the $rawData value to match the parent.