feat(ngModel) Allow running the formatters without a change to the modelValue

Fixes #3407

Author: realityking

src/ng/directive/ngModel.js

@@ -799,6 +799,28 @@ var NgModelController = ['$scope', '$exceptionHandler', '$attrs', '$element', '$
     }
   };
 
+  function formatValue(modelValue) {
+    var formatters = ctrl.$formatters,
+        idx = formatters.length;
+
+    var viewValue = modelValue;
+    while (idx--) {
+      viewValue = formatters[idx](viewValue);
+    }
+
+    return viewValue;
+  }
+
+  this.$runFormatters = function() {
+    var modelValue = this.$modelValue,
+        viewValue = formatValue(this.$modelValue);
+
+    if (this.$viewValue !== viewValue) {
+      this.$viewValue = ctrl.$$lastCommittedViewValue = viewValue;
+      this.$render();
+    }
+  };
+
   // model -> value
   // Note: we cannot use a normal scope.$watch as we want to detect the following:
   // 1. scope value is 'a'
@@ -814,19 +836,11 @@ var NgModelController = ['$scope', '$exceptionHandler', '$attrs', '$element', '$
     // TODO(perf): why not move this to the action fn?
     if (modelValue !== ctrl.$modelValue) {
       ctrl.$modelValue = ctrl.$$rawModelValue = modelValue;
+      var oldViewValue = ctrl.$viewValue;
 
-      var formatters = ctrl.$formatters,
-          idx = formatters.length;
-
-      var viewValue = modelValue;
-      while (idx--) {
-        viewValue = formatters[idx](viewValue);
-      }
-      if (ctrl.$viewValue !== viewValue) {
-        ctrl.$viewValue = ctrl.$$lastCommittedViewValue = viewValue;
-        ctrl.$render();
-
-        ctrl.$$runValidators(undefined, modelValue, viewValue, noop);
+      ctrl.$runFormatters();
+      if (ctrl.$viewValue !== oldViewValue) {
+        ctrl.$$runValidators(undefined, modelValue, ctrl.$viewValue, noop);
       }
     }
 

test/ng/directive/ngModelSpec.js

@@ -578,6 +578,32 @@ describe('ngModel', function() {
 
         dealoc(form);
       }));
+
+      describe('$runFormatters', function() {
+        it('should reformat the value', function() {
+          spyOn(ctrl, '$render');
+          ctrl.$validators.spyValidator = jasmine.createSpy('spyValidator');
+          scope.$apply('value = "first"');
+          ctrl.$formatters.push(function(value) {
+            return 'change';
+          });
+          ctrl.$runFormatters();
+          expect(ctrl.$viewValue).toBe('change');
+        });
+
+        it('should not rerender nor validate in case view value is not changed', function() {
+          ctrl.$formatters.push(function(value) {
+            return 'nochange';
+          });
+
+          spyOn(ctrl, '$render');
+          ctrl.$validators.spyValidator = jasmine.createSpy('spyValidator');
+          scope.$apply('value = "first"');
+          ctrl.$runFormatters();
+          expect(ctrl.$validators.spyValidator).toHaveBeenCalledOnce();
+          expect(ctrl.$render).toHaveBeenCalledOnce();
+        });
+      });
     });