Merge pull request #2064 from NativeScript/nnikolov/BindingChangingContextFix

Additional fix for changing binding context issue.

apps/tests/ui/bindable-tests.ts

@@ -492,6 +492,7 @@ export var test_bindingToNestedPropertyWithValueSyntax = function () {
     }, bindingSource);
 
     TKUnit.assertEqual(testElement.get("targetPropertyName"), "testValue");
+    TKUnit.assertTrue(bindingSource['$value'] === undefined, "We should not add $value to bindingSource.");
 }
 
 export var test_TwoElementsBindingToSameBindingContext = function () {
@@ -546,6 +547,58 @@ export var test_BindingToSource_FailsAfterBindingContextChange = function () {
     helper.buildUIAndRunTest(createLabel(), testFunc);
 }
 
+export var test_BindingToParentView_ShouldNotLeaveGarbageInViewModel = function () {
+    var createStack = function () {
+        var stack = new stackLayoutModule.StackLayout();
+        var label = new labelModule.Label();
+        stack.addChild(label);
+        return stack;
+    }
+    var stackViewModel = new observable.Observable();
+    var expectedValue = "testValue";
+    stackViewModel.set("testProperty", expectedValue);
+
+    var testFunc = function (views: Array<viewModule.View>) {
+        let testStack = <stackLayoutModule.StackLayout>(views[0]);
+        testStack.bindingContext = stackViewModel;
+        
+        let testLabel = <labelModule.Label>(testStack.getChildAt(0));
+        testLabel.bind({ sourceProperty: "$parent.testProperty", targetProperty: "text", expression: "$parent.testProperty"});
+
+        TKUnit.assertEqual(testLabel.text, expectedValue);
+        TKUnit.assertTrue(stackViewModel['$parent'] === undefined, "stackViewModel['$parent'] should be removed from parent binding context.");
+        TKUnit.assertTrue(testLabel.bindingContext['$parent'] === undefined, "testLabel.bindingContext['$parent'] should be removed from parent binding context.");
+    }
+
+    helper.buildUIAndRunTest(createStack(), testFunc);
+}
+
+export var test_BindingToParentsView_ShouldNotLeaveGarbageInViewModel = function () {
+    var createStack = function () {
+        var stack = new stackLayoutModule.StackLayout();
+        var label = new labelModule.Label();
+        stack.addChild(label);
+        return stack;
+    }
+    var stackViewModel = new observable.Observable();
+    var expectedValue = "testValue";
+    stackViewModel.set("testProperty", expectedValue);
+
+    var testFunc = function (views: Array<viewModule.View>) {
+        let testStack = <stackLayoutModule.StackLayout>(views[0]);
+        testStack.bindingContext = stackViewModel;
+        
+        let testLabel = <labelModule.Label>(testStack.getChildAt(0));
+        testLabel.bind({ sourceProperty: "$parents['StackLayout'].testProperty", targetProperty: "text", expression: "$parents['StackLayout'].testProperty"});
+
+        TKUnit.assertEqual(testLabel.text, expectedValue);
+        TKUnit.assertTrue(stackViewModel['$parent'] === undefined, "stackViewModel['$parent'] should be removed from parent binding context.");
+        TKUnit.assertTrue(testLabel.bindingContext['$parents'] === undefined, "testLabel.bindingContext['$parents'] should be removed from parent binding context.");
+    }
+
+    helper.buildUIAndRunTest(createStack(), testFunc);
+}
+
 export function test_BindingToDictionaryAtAppLevel() {
     var createLabel = function () {
         var label = new labelModule.Label();
@@ -998,6 +1051,7 @@ export function test_$ValueSupportWithinExpression() {
     model.set("anyColor", "red");
 
     TKUnit.assertEqual(bindableObj.get("test"), "red", "When anyColor is red test property should be red too.");
+    TKUnit.assertTrue(model['$value'] === undefined, "We should not add $value to binding context.");
 }
 
 class DummyNestedClass extends observable.Observable {

ui/core/bindable.ts

@@ -330,7 +330,7 @@ export class Binding {
             }
 
             let updateExpression = this.prepareExpressionForUpdate();
-            this.prepareContextForExpression(changedModel, updateExpression);
+            this.prepareContextForExpression(changedModel, updateExpression, undefined);
 
             let expressionValue = this._getExpressionValue(updateExpression, true, changedModel);
             if (expressionValue instanceof Error) {
@@ -357,7 +357,7 @@ export class Binding {
                     }
                 }
 
-                this.prepareContextForExpression(context, expression);
+                this.prepareContextForExpression(context, expression, addedProps);
                 model[contextKey] = context;
                 let result = exp.getValue(model, isBackConvert, changedModel ? changedModel : model);
                 // clear added props
@@ -443,17 +443,20 @@ export class Binding {
         }
     }
 
-    private prepareContextForExpression(model: Object, expression: string) {
+    private prepareContextForExpression(model: Object, expression: string, newProps: Array<string>) {
         let parentViewAndIndex: { view: viewModule.View, index: number };
         let parentView;
+        let addedProps = newProps || [];
         if (expression.indexOf(bc.bindingValueKey) > -1) {
             model[bc.bindingValueKey] = model;
+            addedProps.push(bc.bindingValueKey);
         }
 
         if (expression.indexOf(bc.parentValueKey) > -1) {
             parentView = this.getParentView(this.target.get(), bc.parentValueKey).view;
             if (parentView) {
                 model[bc.parentValueKey] = parentView.bindingContext;
+                addedProps.push(bc.parentValueKey);
             }
         }
 
@@ -464,6 +467,7 @@ export class Binding {
                 if (parentViewAndIndex.view) {
                     model[bc.parentsValueKey] = model[bc.parentsValueKey] || {};
                     model[bc.parentsValueKey][parentViewAndIndex.index] = parentViewAndIndex.view.bindingContext;
+                    addedProps.push(bc.parentsValueKey);
                 }
             }
         }