fix($parse): one-time binding for literal expressions works as expected

Meaning the watcher is only removed when all the properties of the object, or all the elements of the array, are defined. Closes angular#8209
walter-psjr · Aug 2, 2014 · c024f28 · c024f28
1 parent 108a69b
commit c024f28
Show file tree

Hide file tree

Showing 2 changed files with 88 additions and 2 deletions.
diff --git a/src/ng/parse.js b/src/ng/parse.js
@@ -1012,8 +1012,12 @@ function $ParseProvider() {
             var parser = new Parser(lexer, $filter, $parseOptions);
             parsedExpression = parser.parse(exp);
 
-            if (parsedExpression.constant) parsedExpression.$$watchDelegate = constantWatch;
-            else if (oneTime) parsedExpression.$$watchDelegate = oneTimeWatch;
+            if (parsedExpression.constant) {
+              parsedExpression.$$watchDelegate = constantWatch;
+            } else if (oneTime) {
+              parsedExpression.$$watchDelegate = parsedExpression.literal ?
+                oneTimeLiteralWatch : oneTimeWatch;
+            }
 
             if (cacheKey !== 'hasOwnProperty') {
               // Only cache the value if it's not going to mess up the cache object
@@ -1050,6 +1054,30 @@ function $ParseProvider() {
       }, objectEquality);
     }
 
+    function oneTimeLiteralWatch(scope, listener, objectEquality, parsedExpression) {
+      var unwatch;
+      return unwatch = scope.$watch(function oneTimeWatch(scope) {
+        return parsedExpression(scope);
+      }, function oneTimeListener(value, old, scope) {
+        if (isFunction(listener)) {
+          listener.call(this, value, old, scope);
+        }
+        if (isAllDefined(value)) {
+          scope.$$postDigest(function () {
+            if(isAllDefined(value)) unwatch();
+          });
+        }
+      }, objectEquality);
+
+      function isAllDefined(value) {
+        var allDefined = true;
+        forEach(value, function (val) {
+          if (!isDefined(val)) allDefined = false;
+        });
+        return allDefined;
+      }
+    }
+
     function constantWatch(scope, listener, objectEquality, parsedExpression) {
       var unwatch;
       return unwatch = scope.$watch(function constantWatch(scope) {

diff --git a/test/ng/parseSpec.js b/test/ng/parseSpec.js
@@ -1174,6 +1174,64 @@ describe('parser', function() {
           $rootScope.$digest();
           expect(fn()).toEqual(null);
         }));
+
+        describe('literal expressions', function () {
+          it('should only become stable when all the properties of an object have defined values', inject(function ($parse, $rootScope, log){
+            var fn = $parse('::{foo: foo, bar: bar}');
+            $rootScope.$watch(fn, function(value) { log(value); }, true);
+
+            expect(log.empty()).toEqual([]);
+            expect($rootScope.$$watchers.length).toBe(1);
+
+            $rootScope.$digest();
+            expect($rootScope.$$watchers.length).toBe(1);
+            expect(log.empty()).toEqual([{foo: undefined, bar: undefined}]);
+
+            $rootScope.foo = 'foo';
+            $rootScope.$digest();
+            expect($rootScope.$$watchers.length).toBe(1);
+            expect(log.empty()).toEqual([{foo: 'foo', bar: undefined}]);
+
+            $rootScope.foo = 'foobar';
+            $rootScope.bar = 'bar';
+            $rootScope.$digest();
+            expect($rootScope.$$watchers.length).toBe(0);
+            expect(log.empty()).toEqual([{foo: 'foobar', bar: 'bar'}]);
+
+            $rootScope.foo = 'baz';
+            $rootScope.$digest();
+            expect($rootScope.$$watchers.length).toBe(0);
+            expect(log.empty()).toEqual([]);
+          }));
+
+          it('should only become stable when all the elements of an array have defined values', inject(function ($parse, $rootScope, log){
+            var fn = $parse('::[foo,bar]');
+            $rootScope.$watch(fn, function(value) { log(value); }, true);
+
+            expect(log.empty()).toEqual([]);
+            expect($rootScope.$$watchers.length).toBe(1);
+
+            $rootScope.$digest();
+            expect($rootScope.$$watchers.length).toBe(1);
+            expect(log.empty()).toEqual([[undefined, undefined]]);
+
+            $rootScope.foo = 'foo';
+            $rootScope.$digest();
+            expect($rootScope.$$watchers.length).toBe(1);
+            expect(log.empty()).toEqual([['foo', undefined]]);
+
+            $rootScope.foo = 'foobar';
+            $rootScope.bar = 'bar';
+            $rootScope.$digest();
+            expect($rootScope.$$watchers.length).toBe(0);
+            expect(log.empty()).toEqual([['foobar', 'bar']]);
+
+            $rootScope.foo = 'baz';
+            $rootScope.$digest();
+            expect($rootScope.$$watchers.length).toBe(0);
+            expect(log.empty()).toEqual([]);
+          }));
+        });
       });
 
       describe('locals', function() {