Add $resolved property to get $loaded() state (#837)

src/database/FirebaseArray.js

@@ -88,6 +88,14 @@
 
         this._sync.init(this.$list);
 
+        // $resolved provides quick access to the current state of the $loaded() promise.
+        // This is useful in data-binding when needing to delay the rendering or visibilty
+        // of the data until is has been loaded from firebase.
+        this.$list.$resolved = false;
+        this.$loaded().finally(function() {
+          self.$list.$resolved = true;
+        });
+
         return this.$list;
       }
 

src/database/FirebaseObject.js

@@ -36,6 +36,7 @@
         if( !(this instanceof FirebaseObject) ) {
           return new FirebaseObject(ref);
         }
+        var self = this;
         // These are private config props and functions used internally
         // they are collected here to reduce clutter in console.log and forEach
         this.$$conf = {
@@ -63,6 +64,14 @@
 
         // start synchronizing data with Firebase
         this.$$conf.sync.init();
+
+        // $resolved provides quick access to the current state of the $loaded() promise.
+        // This is useful in data-binding when needing to delay the rendering or visibilty
+        // of the data until is has been loaded from firebase.
+        this.$resolved = false;
+        this.$loaded().finally(function() {
+          self.$resolved = true;
+        });
       }
 
       FirebaseObject.prototype = {

tests/unit/FirebaseArray.spec.js

@@ -590,6 +590,39 @@ describe('$firebaseArray', function () {
     });
   });
 
+  describe('$resolved', function () {
+    it('should return false on init', function () {
+      arr = $firebaseArray(stubRef());
+      expect(arr.$resolved).toBe(false);
+    });
+
+    it('should return true once $loaded() promise is resolved', function () {
+      arr = $firebaseArray(stubRef());
+
+      arr.$loaded()
+        .finally(function () {
+          expect(arr.$resolved).toBe(true);
+          done();
+        });
+    });
+
+    it('should return true once $loaded() promise is rejected', function () {
+      var err = new Error('test_fail');
+
+      spyOn(firebase.database.Reference.prototype, "once").and.callFake(function (event, cb, cancel_cb) {
+        cancel_cb(err);
+      });
+
+      arr = $firebaseArray(stubRef());
+
+      arr.$loaded()
+        .finally(function () {
+          expect(arr.$resolved).toBe(true);
+          done();
+        });
+    });
+  });
+
   describe('$ref', function() {
     it('should return Firebase instance it was created with', function() {
       var ref = stubRef();

tests/unit/FirebaseObject.spec.js

@@ -240,6 +240,40 @@ describe('$firebaseObject', function() {
     });
   });
 
+  describe('$resolved', function () {
+    it('should return false on init', function () {
+      var ref = stubRef();
+      var obj = $firebaseObject(ref);
+      expect(obj.$resolved).toBe(false);
+    });
+
+    it('should return true once $loaded() promise is resolved', function () {
+      var obj = makeObject();
+
+      obj.$loaded()
+        .finally(function () {
+          expect(obj.$resolved).toBe(true);
+          done();
+        });
+    });
+
+    it('should return true once $loaded() promise is rejected', function () {
+      var err = new Error('test_fail');
+
+      spyOn(firebase.database.Reference.prototype, "once").and.callFake(function (event, cb, cancel_cb) {
+        cancel_cb(err);
+      });
+
+      var obj = makeObject();
+
+      obj.$loaded()
+        .finally(function () {
+          expect(obj.$resolved).toBe(true);
+          done();
+        });
+    });
+  });
+
   describe('$ref', function () {
     it('should return the Firebase instance that created it', function () {
       var ref = stubRef();