feat(ngModel): expose $processModelValue to run model -> view pipeline

Closes angular#3407
Closes angular#10764

src/ng/directive/ngModel.js

@@ -878,6 +878,139 @@ NgModelController.prototype = {
    */
   $overrideModelOptions: function(options) {
     this.$options = this.$options.createChild(options);
+  },
+
+  /**
+   * @ngdoc method
+   *
+   * @name  ngModel.NgModelController#$processModelValue
+
+   * @description
+   *
+   * Runs the model -> view pipeline on the current
+   * {@link ngModel.NgModelController#$modelValue $modelValue}.
+   *
+   * The following actions are performed by this method:
+   *
+   * - the `$modelValue` is run through the {@link ngModel.NgModelController#$formatters $formatters}
+   * and the result is set to the {@link ngModel.NgModelController#$viewValue $viewValue}
+   * - the `ng-empty` or `ng-not-empty` class is set on the element
+   * - if the `$viewValue` has changed:
+   *   - {@link ngModel.NgModelController#$render $render} is called on the control
+   *   - the {@link ngModel.NgModelController#$validators $validators} are run and
+   *   the validation status is set.
+   *
+   * This method is called by ngModel internally when the bound scope value changes.
+   * Application developers usually do not have to call this function themselves.
+   *
+   * This function can be used when the `$viewValue` or the rendered DOM value are not correctly
+   * formatted and the `$modelValue` must be run through the `$formatters` again.
+   *
+   * For example, consider a text input with an autocomplete list (for fruit), where the items are
+   * objects with a name and an id.
+   * A user enters `ap` and then selects `Apricot` from the list.
+   * Based on this, the autocomplete widget will call `$setViewValue({name: 'Apricot', id: 443})`,
+   * but the rendered value will still be `ap`.
+   * The widget can then call `ctrl.$processModelValue()` to run the model -> view
+   * pipeline again, which formats the object to the string `Apricot`,
+   * then updates the `$viewValue`, and finally renders it in the DOM.
+   *
+   * @example
+   * <example module="inputExample" name="ng-model-process">
+     <file name="app.js">
+      angular.module('inputExample', [])
+        .directive('processModel', function() {
+          return {
+            require: 'ngModel',
+            link: function(scope, element, attrs, ngModel) {
+
+              ngModel.$formatters.push(function(value) {
+                if (angular.isObject(value) && value.name) {
+                  return value.name;
+                }
+
+                return value;
+              });
+
+              ngModel.$parsers.push(function(value) {
+                if (angular.isString(value)) {
+                  return scope.items.find(function(item) {
+                    return item.name === value;
+                  }) || value;
+                }
+
+                return value;
+              });
+
+              scope.items = [
+                {name: 'Apricot', id: 443},
+                {name: 'Clementine', id: 972},
+                {name: 'Durian', id: 169},
+                {name: 'Jackfruit', id: 982},
+                {name: 'Strawberry', id: 863}
+              ];
+
+              scope.select = function(item) {
+                ngModel.$setViewValue(item);
+                ngModel.$processModelValue();
+              };
+            }
+          };
+        });
+     </file>
+     <file name="index.html">
+       <div style="display: flex;">
+         <div style="margin-right: 30px;">
+           Search Fruit:
+           <input ng-model="val" process-model />
+
+           <ul>
+             <li ng-repeat="item in items | filter:val"><button ng-click="select(item)">{{item.name}}</li>
+           </ul>
+         </div>
+         <div>
+           Model:<br>
+           <pre>{{val | json}}</pre>
+         </div>
+       </div>
+     </file>
+   * </example>
+   *
+   */
+  $processModelValue: function() {
+    var viewValue = this.$$format();
+
+    if (this.$viewValue !== viewValue) {
+      this.$$updateEmptyClasses(viewValue);
+      this.$viewValue = this.$$lastCommittedViewValue = viewValue;
+      this.$render();
+      // It is possible that model and view value have been updated during render
+      this.$$runValidators(this.$modelValue, this.$viewValue, noop);
+    }
+  },
+
+  /**
+   * This method is called internally to run the $formatters on the $modelValue
+   */
+  $$format: function() {
+    var formatters = this.$formatters,
+        idx = formatters.length;
+
+    var viewValue = this.$modelValue;
+    while (idx--) {
+      viewValue = formatters[idx](viewValue);
+    }
+
+    return viewValue;
+  },
+
+  /**
+   * This method is called internally when the bound scope value changes.
+   */
+  $$setModelValue: function(modelValue) {
+    this.$modelValue = this.$$rawModelValue = modelValue;
+    this.$$parserValid = undefined;
+    this.$processModelValue();
   }
 };
 
@@ -894,30 +1027,14 @@ function setupModelWatcher(ctrl) {
     var modelValue = ctrl.$$ngModelGet(scope);
 
     // if scope model value and ngModel value are out of sync
-    // TODO(perf): why not move this to the action fn?
+    // This cannot be moved to the action function, because it would not catch the
+    // case where the model is changed in the ngChange function or the model setter
     if (modelValue !== ctrl.$modelValue &&
-       // checks for NaN is needed to allow setting the model to NaN when there's an asyncValidator
-        // eslint-disable-next-line no-self-compare
-       (ctrl.$modelValue === ctrl.$modelValue || modelValue === modelValue)
+      // checks for NaN is needed to allow setting the model to NaN when there's an asyncValidator
+      // eslint-disable-next-line no-self-compare
+     (ctrl.$modelValue === ctrl.$modelValue || modelValue === modelValue)
     ) {
-      ctrl.$modelValue = ctrl.$$rawModelValue = modelValue;
-      ctrl.$$parserValid = undefined;
-
-      var formatters = ctrl.$formatters,
-          idx = formatters.length;
-
-      var viewValue = modelValue;
-      while (idx--) {
-        viewValue = formatters[idx](viewValue);
-      }
-      if (ctrl.$viewValue !== viewValue) {
-        ctrl.$$updateEmptyClasses(viewValue);
-        ctrl.$viewValue = ctrl.$$lastCommittedViewValue = viewValue;
-        ctrl.$render();
-
-        // It is possible that model and view value have been updated during render
-        ctrl.$$runValidators(ctrl.$modelValue, ctrl.$viewValue, noop);
-      }
+      ctrl.$$setModelValue(modelValue);
     }
 
     return modelValue;

test/ng/directive/ngModelSpec.js

@@ -603,6 +603,113 @@ describe('ngModel', function() {
         expect(ctrl.$modelValue).toBeNaN();
 
       }));
+
+      describe('$processModelValue', function() {
+        // Emulate setting the model on the scope
+        function setModelValue(ctrl, value) {
+          ctrl.$modelValue = ctrl.$$rawModelValue = value;
+          ctrl.$$parserValid = undefined;
+        }
+
+        it('should run the model -> view pipeline', function() {
+          var log = [];
+          var input = ctrl.$$element;
+
+          ctrl.$formatters.unshift(function(value) {
+            log.push(value);
+            return value + 2;
+          });
+
+          ctrl.$formatters.unshift(function(value) {
+            log.push(value);
+            return value + '';
+          });
+
+          spyOn(ctrl, '$render');
+
+          setModelValue(ctrl, 3);
+
+          expect(ctrl.$modelValue).toBe(3);
+
+          ctrl.$processModelValue();
+
+          expect(ctrl.$modelValue).toBe(3);
+          expect(log).toEqual([3, 5]);
+          expect(ctrl.$viewValue).toBe('5');
+          expect(ctrl.$render).toHaveBeenCalledOnce();
+        });
+
+        it('should add the validation and empty-state classes',
+          inject(function($compile, $rootScope, $animate) {
+            var input = $compile('<input name="myControl" maxlength="1" ng-model="value" >')($rootScope);
+            $rootScope.$digest();
+
+            spyOn($animate, 'addClass');
+            spyOn($animate, 'removeClass');
+
+            var ctrl = input.controller('ngModel');
+
+            expect(input).toHaveClass('ng-empty');
+            expect(input).toHaveClass('ng-valid');
+
+            setModelValue(ctrl, 3);
+            ctrl.$processModelValue();
+
+            // $animate adds / removes classes in the $$postDigest, which
+            // we cannot trigger with $digest, because that would set the model from the scope,
+            // so we simply check if the functions have been called
+            expect($animate.removeClass.calls.mostRecent().args[0][0]).toBe(input[0]);
+            expect($animate.removeClass.calls.mostRecent().args[1]).toBe('ng-empty');
+
+            expect($animate.addClass.calls.mostRecent().args[0][0]).toBe(input[0]);
+            expect($animate.addClass.calls.mostRecent().args[1]).toBe('ng-not-empty');
+
+            $animate.removeClass.calls.reset();
+            $animate.addClass.calls.reset();
+
+            setModelValue(ctrl, 35);
+            ctrl.$processModelValue();
+
+            expect($animate.addClass.calls.argsFor(1)[0][0]).toBe(input[0]);
+            expect($animate.addClass.calls.argsFor(1)[1]).toBe('ng-invalid');
+
+            expect($animate.addClass.calls.argsFor(2)[0][0]).toBe(input[0]);
+            expect($animate.addClass.calls.argsFor(2)[1]).toBe('ng-invalid-maxlength');
+          })
+        );
+
+        // this is analogue to $setViewValue
+        it('should run the model -> view pipeline even if the value has not changed', function() {
+          var log = [];
+
+          ctrl.$formatters.unshift(function(value) {
+            log.push(value);
+            return value + 2;
+          });
+
+          ctrl.$formatters.unshift(function(value) {
+            log.push(value);
+            return value + '';
+          });
+
+          spyOn(ctrl, '$render');
+
+          setModelValue(ctrl, 3);
+          ctrl.$processModelValue();
+
+          expect(ctrl.$modelValue).toBe(3);
+          expect(ctrl.$viewValue).toBe('5');
+          expect(log).toEqual([3, 5]);
+          expect(ctrl.$render).toHaveBeenCalledOnce();
+
+          ctrl.$processModelValue();
+          expect(ctrl.$modelValue).toBe(3);
+          expect(ctrl.$viewValue).toBe('5');
+          expect(log).toEqual([3, 5, 3, 5]);
+          // $render() is not called if the viewValue didn't change
+          expect(ctrl.$render).toHaveBeenCalledOnce();
+        });
+      });
     });