feat(FirebaseListFactory): add $key and $value field to unwrapped snapshots

Closes angular#78

Author: jeffbcross

src/utils/firebase_list_factory.spec.ts

@@ -4,7 +4,8 @@ import {
   onChildAdded,
   onChildChanged,
   onChildRemoved,
-  onChildUpdated
+  onChildUpdated,
+  unwrapMapFn
 } from './firebase_list_factory';
 import {FirebaseListObservable} from './firebase_list_observable';
 import {
@@ -183,6 +184,37 @@ describe('FirebaseListFactory', () => {
         onChildRemoved([val1, val2, val3], val2)
       ).toEqual([val1, val3]);
     });
+  });
+
+
+  describe('unwrapMapFn', () => {
+    var val = {unwrapped: true};
+    var snapshot = {
+      key: () => 'key',
+      val: () => val
+    };
+
+    it('should return an object value with a $key property', () => {
+      expect(unwrapMapFn(snapshot as FirebaseDataSnapshot)).toEqual({
+        $key: 'key',
+        unwrapped: true
+      });
+    });
 
+
+    it('should return an object value with a $value property if value is scalar', () => {
+      expect(unwrapMapFn(Object.assign(snapshot, {val: () => 5}) as FirebaseDataSnapshot)).toEqual({
+        $key: 'key',
+        $value: 5
+      });
+      expect(unwrapMapFn(Object.assign(snapshot, {val: () => false}) as FirebaseDataSnapshot)).toEqual({
+        $key: 'key',
+        $value: false
+      });
+      expect(unwrapMapFn(Object.assign(snapshot, {val: () => 'lol'}) as FirebaseDataSnapshot)).toEqual({
+        $key: 'key',
+        $value: 'lol'
+      });
+    });
   });
 });

src/utils/firebase_list_factory.ts

@@ -1,4 +1,4 @@
-import {FirebaseListObservable} from './firebase_list_observable';
+import {FirebaseListObservable, AFUnwrappedDataSnapshot} from './firebase_list_observable';
 import {Observer} from 'rxjs/Observer';
 import * as Firebase from 'firebase';
 
@@ -49,8 +49,15 @@ export interface FirebaseListFactoryOpts {
   preserveSnapshot?: boolean;
 }
 
-function unwrapMapFn (snapshot:FirebaseDataSnapshot): any {
-  return snapshot.val();
+export function unwrapMapFn (snapshot:FirebaseDataSnapshot): AFUnwrappedDataSnapshot {
+  var unwrapped = snapshot.val();
+  if ((/string|number|boolean/).test(typeof unwrapped)) {
+    unwrapped = {
+      $value: unwrapped
+    };
+  }
+  unwrapped.$key = snapshot.key();
+  return unwrapped;
 }
 
 export function onChildAdded(arr:any[], child:any, prevKey:string): any[] {

src/utils/firebase_list_observable.ts

@@ -23,3 +23,8 @@ export class FirebaseListObservable<T> extends Observable<T> {
     this._ref.push(val);
   }
 }
+
+export interface AFUnwrappedDataSnapshot {
+  $key: string;
+  $value?: string | number | boolean;
+}