AngularJS does not send hidden field value

For a specific use case I have to submit a single form the "old way". Means, I use a form with action="". The response is streamed, so I am not reloading the page. I am completely aware that a typical AngularJS app would not submit a form that way, but so far I have no other choice.

That said, i tried to populate some hidden fields from Angular:

<input type="hidden" name="someData" ng-model="data" /> {{data}}

Please note, the correct value in data is shown.

The form looks like a standard form:

<form id="aaa" name="aaa" action="/reports/aaa.html" method="post">
...
<input type="submit" value="Export" />
</form>

If I hit submit, no value is sent to the server. If I change the input field to type "text" it works as expected. My assumption is the hidden field is not really populated, while the text field actually is shown due two-way-binding.

Any ideas how I can submit a hidden field populated by AngularJS?

Solution 1:

You cannot use double binding with hidden field. The solution is to use brackets :

<input type="hidden" name="someData" value="{{data}}" /> {{data}}

EDIT : See this thread on github : https://github.com/angular/angular.js/pull/2574

EDIT:

Since Angular 1.2, you can use 'ng-value' directive to bind an expression to the value attribute of input. This directive should be used with input radio or checkbox but works well with hidden input.

Here is the solution using ng-value:

<input type="hidden" name="someData" ng-value="data" />

Here is a fiddle using ng-value with an hidden input: http://jsfiddle.net/6SD9N

Solution 2:

You can always use a type=text and display:none; since Angular ignores hidden elements. As OP says, normally you wouldn't do this, but this seems like a special case.

<input type="text" name="someData" ng-model="data" style="display: none;"/>

Solution 3:

In the controller:

$scope.entityId = $routeParams.entityId;

In the view:

<input type="hidden" name="entityId" ng-model="entity.entityId" ng-init="entity.entityId = entityId" />

Solution 4:

I've found a nice solution written by Mike on sapiensworks. It is as simple as using a directive that watches for changes on your model:

.directive('ngUpdateHidden',function() {
    return function(scope, el, attr) {
        var model = attr['ngModel'];
        scope.$watch(model, function(nv) {
            el.val(nv);
        });
    };
})

and then bind your input:

<input type="hidden" name="item.Name" ng-model="item.Name" ng-update-hidden />

But the solution provided by tymeJV could be better as input hidden doesn't fire change event in javascript as yycorman told on this post, so when changing the value through a jQuery plugin will still work.

Edit I've changed the directive to apply the a new value back to the model when change event is triggered, so it will work as an input text.

.directive('ngUpdateHidden', function () {
    return {
        restrict: 'AE', //attribute or element
        scope: {},
        replace: true,
        require: 'ngModel',
        link: function ($scope, elem, attr, ngModel) {
            $scope.$watch(ngModel, function (nv) {
                elem.val(nv);
            });
            elem.change(function () { //bind the change event to hidden input
                $scope.$apply(function () {
                    ngModel.$setViewValue(  elem.val());
                });
            });
        }
    };
})

so when you trigger $("#yourInputHidden").trigger('change') event with jQuery, it will update the binded model as well.