setViewValue in directive on input not updating actual visible input value

Question

I've been fighting with this for almost two days. I hope you guys can help me.

Summary:
I have problems setting the view value of some input fields programatically.
I have a form with inputs whose values are saved before the form is removed (multiple elements and multiple forms possible, user might close a form, and reopen later). On reopening the form I want to restore the previous view values (main reason is to get back also the invalid view values which were not saved in the model). This doesn't work.

If I call ctrl.$setViewValue(previousValue) I get the model (visibly) updated (if valid), the view values of the formControl (while debugging in console) are changed too, but I don't get them actually rendered in the input fields. I don't understand why :(

I reduced the problem to this fiddle:
http://jsfiddle.net/g0mjk750/1/

javascript

var app = angular.module('App', [])

    function Controller($scope) {
        $scope.form = {
            userContent: 'initial content'
        }
    }
app.controller('Controller', Controller);
app.directive('resetOnBlur', function () {
    return {
        restrict: 'A',
        require: 'ngModel',
        link: function (scope, element, attrs, ngModel) {
            element.bind('blur', function () {
                console.log(ngModel);
                scope.$apply(setAnotherValue);
            });
            function setAnotherValue() {
                ngModel.$setViewValue("I'm a new value of the model. I've been set using the setViewValue method");
            }
        }
    };
});

Html

<form name="myForm" ng-app="App" ng-controller="Controller" class="form">
    Text: {{form.userContent}}
    <hr />
    If you remove the text, "Required!" will be displayed.<br/>
    If you change the input value, the text will update.<br/>
    If you blur, the text will update, but the (visible) input value not.
    <hr />
    <input class="input" type="text" ng-model="form.userContent" name="userContent" reset-on-blur required></textarea>
    <span ng-show="myForm.userContent.$error.required">Required!</span>
</form>

I hope you guys can explain to me why this doesn't work and how to fix this...

Answer 1

You need to call ngModel.$render() to have the viewvalue change reflected in the input. There is no watch created on $viewValue so that changes are automatically reflected.

   function setAnotherValue() {
        ngModel.$setViewValue("I'm a new value of the model. I've been set using the setViewValue method");
        ngModel.$render();
    }

Plnkr

Default implementation of $render does this:-

 element.val(ctrl.$isEmpty(ctrl.$viewValue) ? '' : ctrl.$viewValue);

However you can override and customize your implementation for $render as well..