AngularJS does not send hidden field value

Question

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

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;"/>

In the controller:

$scope.entityId = $routeParams.entityId;

In the view:

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

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.

Found a strange behaviour about this hidden value () and we can't make it to work.

After playing around we found the best way is just defined the value in controller itself after the form scope.

.controller('AddController', [$scope, $http, $state, $stateParams, function($scope, $http, $state, $stateParams) {

    $scope.routineForm = {};
    $scope.routineForm.hiddenfield1 = "whatever_value_you_pass_on";

    $scope.sendData = function {

// JSON http post action to API 
}

}])

I achieved this via -

 <p style="display:none">{{user.role="store_user"}}</p>

update @tymeJV 's answer eg:

 <div style="display: none">
    <input type="text" name='price' ng-model="price" ng-init="price = <%= @product.price.to_s %>" >
 </div>