Dynamic validation and name in a form with AngularJS

The question:

I have this form : http://jsfiddle.net/dfJeN/

As you can see the name value for the input is statically set :

name="username"

, the form validation works fine (add something and remove all text from the input, a text must appears).

Then I try to dynamically set the name value : http://jsfiddle.net/jNWB8/

name="{input.name}"

Then I apply this to my validation

login.{{input.name}}.$error.required

(this pattern will be used in an ng-repeat) but my form validation is broken. It is correctly interpreted in my browser (if I inspect the element I saw login.username.$error.required).

Any Idea ?

EDIT: After logging the scope in the console it appears that the

{{input.name}}

expression is not interpolate. My form as an {{input.name}} attribute but no username.

UPDATE: Since 1.3.0-rc.3 name=”{{input.name}}” works as expected. Please see #1404

The Solutions:

Below are the methods you can try. The first solution is probably the best. Try others if the first one doesn’t work. Senior developers aren’t just copying/pasting – they read the methods carefully & apply them wisely to each case.

Method 1

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.

Method 2

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>

Method 3

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.

Method 4

Nice one by @EnISeeK…. but i got it to be more elegant and less obtrusive to other directives:

.directive("dynamicName",[function(){
    return {
        restrict:"A",
        require: ['ngModel', '^form'],
        link:function(scope,element,attrs,ctrls){
            ctrls[0].$name = scope.$eval(attrs.dynamicName) || attrs.dynamicName;
            ctrls[1].$addControl(ctrls[0]);
        }
    };
}])

Method 5

Just a little improvement over EnlSeek solution

angular.module('test').directive('dynamicName', ["$parse", function($parse) {
 return {
    restrict: 'A',
    priority: 10000, 
    controller : ["$scope", "$element", "$attrs", 
           function($scope, $element, $attrs){
         var name = $parse($attrs.dynamicName)($scope);
         delete($attrs['dynamicName']);
         $element.removeAttr('data-dynamic-name');
         $element.removeAttr('dynamic-name');
          $attrs.$set("name", name);
    }]

  };
}]);

Here is a plunker trial. Here is detailed explantion

Method 6

I expand the @caitp and @Thinkscape solution a bit, to allow dynamically created nested ng-forms, like this:

<div ng-controller="ctrl">
    <ng-form name="form">
        <input type="text" ng-model="static" name="static"/>

        <div ng-repeat="df in dynamicForms">
            <ng-form name="form{{df.id}}">
                <input type="text" ng-model="df.sub" name="sub"/>
                <div>Dirty: <span ng-bind="form{{df.id}}.$dirty"></span></div>
            </ng-form>
        </div>

        <div><button ng-click="consoleLog()">Console Log</button></div>
        <div>Dirty: <span ng-bind="form.$dirty"></span></div>
    </ng-form>      
</div>

Here is my demo on JSFiddle.

Method 7

I used Ben Lesh’s solution and it works well for me. But one problem I faced was that when I added an inner form using ng-form, all of the form states e.g. form.$valid, form.$error etc became undefined if I was using the ng-submit directive.

So if I had this for example:

<form novalidate ng-submit="saveRecord()" name="outerForm">
    <!--parts of the outer form-->
    <ng-form name="inner-form">
      <input name="someInput">
    </ng-form>
    <button type="submit">Submit</button>
</form>

And in the my controller:

$scope.saveRecord = function() {
    outerForm.$valid // this is undefined
}

So I had to go back to using a regular click event for submitting the form in which case it’s necessary to pass the form object:

<form novalidate name="outerForm">  <!--remove the ng-submit directive-->
    <!--parts of the outer form-->
    <ng-form name="inner-form">
      <input name="someInput">
    </ng-form>
    <button type="submit" ng-click="saveRecord(outerForm)">Submit</button>
</form>

And the revised controller method:

$scope.saveRecord = function(outerForm) {
    outerForm.$valid // this works
}

I’m not quite sure why this is but hopefully it helps someone.

Method 8

This issue has been fixed in Angular 1.3+
This is the correct syntax for what you are trying to do:

login[input.name].$invalid

Method 9

if we set dynamic name for a input like the below

<input name="{{dynamicInputName}}" />

then we have use set validation for dynamic name like the below code.

<div ng-messages="login.dynamicInputName.$error">
   <div ng-message="required">
   </div>
</div>


All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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