Merge pull request #218 from NativeScript/observable-json

Implemented Observable constructor that accepts JSON objects.

apps/tests/ui/observable-tests.ts

@@ -18,6 +18,27 @@ class TestObservable extends observable.Observable {
     }
 }
 
+export var test_Observable_Constructor = function () {
+    // <snippet module="data/observable" title="data/observable">
+    // ### Creating an Observable
+    // ``` JavaScript
+    var json = {
+        Name: "John",
+        Age: 34,
+        Married: true
+    };
+    var person = new observable.Observable(json);
+    var name = person.get("Name");
+    var age = person.get("Age");
+    var married = person.get("Married");
+    //// console.log(name + " " + age + " " + married); // Prints out "John 34 true" if uncommented.
+    // ```
+    // </snippet>
+    TKUnit.assert(name === "John", "Expected name is John");
+    TKUnit.assert(age === 34, "Expected age is 34");
+    TKUnit.assert(married === true, "Expected married is true");
+}
+
 export var tests_DummyTestForCodeSnippet = function () {
     // <snippet module="data/observable" title="data/observable">
     // ### Responding to property changes

data/observable/observable.d.ts

@@ -44,6 +44,12 @@ declare module "data/observable" {
      * Observable is used when you want to be notified when a change occurs. Use on/off methods to add/remove listener.
      */
     class Observable {
+
+        /**
+         * Creates an Observable instance and sets its properties accroding to the supplied JSON object.
+         */
+        constructor(json?: any);
+
         /**
          * Gets the name of the constructor function for this instance. E.g. for a Button class this will return "Button".
          */

data/observable/observable.ts

@@ -13,6 +13,16 @@ export module knownEvents {
 export class Observable implements definition.Observable {
     private _observers = {};
 
+    constructor(json?: any) {
+        if (json) {
+            for (var prop in json) {
+                if (json.hasOwnProperty(prop)) {
+                    this.set(prop, json[prop]);
+                }
+            }
+        }
+    }
+
     get typeName(): string {
         return types.getClass(this);
     }