Dynamic validation and name in a form with AngularJS

The problem should be fixed in AngularJS 1.3, according to this discussion on Github.

Meanwhile, here's a temporary solution created by @caitp and @Thinkscape:

// Workaround for bug #1404
// https://github.com/angular/angular.js/issues/1404
// Source: http://plnkr.co/edit/hSMzWC?p=preview
app.config(['$provide', function($provide) {
    $provide.decorator('ngModelDirective', function($delegate) {
        var ngModel = $delegate[0], controller = ngModel.controller;
        ngModel.controller = ['$scope', '$element', '$attrs', '$injector', function(scope, element, attrs, $injector) {
            var $interpolate = $injector.get('$interpolate');
            attrs.$set('name', $interpolate(attrs.name || '')(scope));
            $injector.invoke(controller, this, {
                '$scope': scope,
                '$element': element,
                '$attrs': attrs
            });
        }];
        return $delegate;
    });
    $provide.decorator('formDirective', function($delegate) {
        var form = $delegate[0], controller = form.controller;
        form.controller = ['$scope', '$element', '$attrs', '$injector', function(scope, element, attrs, $injector) {
            var $interpolate = $injector.get('$interpolate');
            attrs.$set('name', $interpolate(attrs.name || attrs.ngForm || '')(scope));
            $injector.invoke(controller, this, {
                '$scope': scope,
                '$element': element,
                '$attrs': attrs
            });
        }];
        return $delegate;
    });
}]);

Demo on JSFiddle.

You can't do what you're trying to do that way.

Assuming what you're trying to do is you need to dynamically add elements to a form, with something like an ng-repeat, you need to use nested ng-form to allow validation of those individual items:

<form name="outerForm">
<div ng-repeat="item in items">
   <ng-form name="innerForm">
      <input type="text" name="foo" ng-model="item.foo" />
      <span ng-show="innerForm.foo.$error.required">required</span>
   </ng-form>
</div>
<input type="submit" ng-disabled="outerForm.$invalid" />
</form>

Sadly, it's just not a well-documented feature of Angular.

Using nested ngForm allows you to access the specific InputController from within the HTML template. However, if you wish to access it from another controller it does not help.

e.g.

<script>
  function OuterController($scope) {
    $scope.inputName = 'dynamicName';

    $scope.doStuff = function() {
      console.log($scope.formName.dynamicName); // undefined
      console.log($scope.formName.staticName); // InputController
    }
  }
</script>

<div controller='OuterController'>
  <form name='myForm'>
    <input name='{{ inputName }}' />
    <input name='staticName' />
  </form>
  <a ng-click='doStuff()'>Click</a>
</div>

I use this directive to help solve the problem:

angular.module('test').directive('dynamicName', function($compile, $parse) {
  return {
    restrict: 'A',
    terminal: true,
    priority: 100000,
    link: function(scope, elem) {
      var name = $parse(elem.attr('dynamic-name'))(scope);
      // $interpolate() will support things like 'skill'+skill.id where parse will not
      elem.removeAttr('dynamic-name');
      elem.attr('name', name);
      $compile(elem)(scope);
    }
  };
});

Now you use dynamic names wherever is needed just the 'dynamic-name' attribute instead of the 'name' attribute.

e.g.

<script>
  function OuterController($scope) {
    $scope.inputName = 'dynamicName';

    $scope.doStuff = function() {
      console.log($scope.formName.dynamicName); // InputController
      console.log($scope.formName.staticName); // InputController
    }
  }
</script>

<div controller='OuterController'>
  <form name='myForm'>
    <input dynamic-name='inputName' />
    <input name='staticName' />
  </form>
  <a ng-click='doStuff()'>Click</a>
</div>