How to validate inputs dynamically created using ng-repeat, ng-show (angular)

AngularJS relies on input names to expose validation errors.

Unfortunately, as of today, it is not possible (without using a custom directive) to dynamically generate a name of an input. Indeed, checking input docs we can see that the name attribute accepts a string only.

To solve the 'dynamic name' problem you need to create an inner form (see ng-form):

<div ng-repeat="social in formData.socials">
      <ng-form name="urlForm">
            <input type="url" name="socialUrl" ng-model="social.url">
            <span class="alert error" ng-show="urlForm.socialUrl.$error.url">URL error</span>
      </ng-form>
  </div>

The other alternative would be to write a custom directive for this.

Here is the jsFiddle showing the usage of the ngForm: http://jsfiddle.net/pkozlowski_opensource/XK2ZT/2/

If you don't want to use ng-form you can use a custom directive that will change the form's name attribute. Place this directive as an attribute on the same element as your ng-model.

If you're using other directives in conjunction, be careful that they don't have the "terminal" property set otherwise this function won't be able to run (given that it has a priority of -1).

For example, when using this directive with ng-options, you must run this one line monkeypatch: https://github.com/AlJohri/bower-angular/commit/eb17a967b7973eb7fc1124b024aa8b3ca540a155

angular.module('app').directive('fieldNameHack', function() {
    return {
      restrict: 'A',
      priority: -1,
      require: ['ngModel'],
      // the ngModelDirective has a priority of 0.
      // priority is run in reverse order for postLink functions.
      link: function (scope, iElement, iAttrs, ctrls) {

        var name = iElement[0].name;
        name = name.replace(/\{\{\$index\}\}/g, scope.$index);

        var modelCtrl = ctrls[0];
        modelCtrl.$name = name;

      }
    };
});

I often find it useful to use ng-init to set the $index to a variable name. For example:

<fieldset class='inputs' ng-repeat="question questions" ng-init="qIndex = $index">

This changes your regular expression to:

name = name.replace(/\{\{qIndex\}\}/g, scope.qIndex);

If you have multiple nested ng-repeats, you can now use these variable names instead of $parent.$index.

Definition of "terminal" and "priority" for directives: https://docs.angularjs.org/api/ng/service/$compile#directive-definition-object

Github Comment regarding need for ng-option monkeypatch: https://github.com/angular/angular.js/commit/9ee2cdff44e7d496774b340de816344126c457b3#commitcomment-6832095 https://twitter.com/aljohri/status/482963541520314369

UPDATE:

You can also make this work with ng-form.

angular.module('app').directive('formNameHack', function() {
    return {
      restrict: 'A',
      priority: 0,
      require: ['form'],
      compile: function() {
        return {
          pre: function(scope, iElement, iAttrs, ctrls) {
            var parentForm = $(iElement).parent().controller('form');
            if (parentForm) {
                var formCtrl = ctrls[0];
                delete parentForm[formCtrl.$name];
                formCtrl.$name = formCtrl.$name.replace(/\{\{\$index\}\}/g, scope.$index);
                parentForm[formCtrl.$name] = formCtrl;
            }
          }
        }
      }
    };
});

Use the ng-form directive inside of the tag in which you are using the ng-repeat directive. You can then use the scope created by the ng-form directive to reference a generic name. For example:

    <div class="form-group col-sm-6" data-ng-form="subForm" data-ng-repeat="field in justificationInfo.justifications"">

        <label for="{{field.label}}"><h3>{{field.label}}</h3></label>
        <i class="icon-valid" data-ng-show="subForm.input.$dirty && subForm.input.$valid"></i>
        <i class="icon-invalid" data-ng-show="subForm.input.$dirty && subForm.input.$invalid"></i>
        <textarea placeholder="{{field.placeholder}}" class="form-control" id="{{field.label}}" name="input" type="text" rows="3" data-ng-model="field.value" required>{{field.value}}</textarea>

    </div>

Credit to: http://www.benlesh.com/2013/03/angular-js-validating-form-elements-in.html

Added more complex example with "custom validation" on the side of controller http://jsfiddle.net/82PX4/3/

<div class='line' ng-repeat='line in ranges' ng-form='lineForm'>
    low: <input type='text' 
                name='low'
                ng-pattern='/^\d+$/' 
                ng-change="lowChanged(this, $index)" ng-model='line.low' />
    up: <input type='text' 
                name='up'
                ng-pattern='/^\d+$/'
                ng-change="upChanged(this, $index)" 
                ng-model='line.up' />
    <a href ng-if='!$first' ng-click='removeRange($index)'>Delete</a>
    <div class='error' ng-show='lineForm.$error.pattern'>
        Must be a number.
    </div>
    <div class='error' ng-show='lineForm.$error.range'>
        Low must be less the Up.
    </div>
</div>

Looking over these solutions, the one provided by Al Johri above is the closest to my needs, but his directive was a little less programmable then I wanted. Here is my version of his solutions:

angular.module("app", [])
    .directive("dynamicFormName", function() {
        return {
            restrict: "A",
            priority: 0,
            require: ["form"],
            compile: function() {
                return {
                    pre: function preLink(scope, iElement, iAttrs, ctrls) {
                        var name = "field" + scope.$index;

                        if (iAttrs.dnfnNameExpression) {
                            name = scope.$eval(iAttrs.dnfnNameExpression);
                        }

                        var parentForm = iElement.parent().controller("form");
                        if (parentForm) {
                            var formCtrl = ctrls[0];
                            delete parentForm[formCtrl.$name];
                            formCtrl.$name = name;
                            parentForm[formCtrl.$name] = formCtrl;
                        }
                    }
                 }
            }
        };
   });

This solution lets you just pass a name generator expression to the directive and avoids the lock down to pattern substitution he was using.

I also had trouble initially with this solution since it didn't show an example of using it in markup, so here is how I used it.

<form name="theForm">
    <div ng-repeat="field in fields">
        <input type="number" ng-form name="theInput{{field.id}}" ng-model="field.value" dynamic-form-name dnfn-name-expression="'theInput' + field.id">        
    </div>
</form>

I have a more complete working example on github.

It is possible and here is how I do the same thing with a table of inputs.

wrap the table in a form like so

Then just use this

I have a form with multi-nested directives that all contain input(s), select(s), etc... These elements are all enclosed in ng-repeats, and dynamic string values.

This is how to use the directive:

<form name="myFormName">
  <nested directives of many levels>
    <your table here>
    <perhaps a td here>
    ex: <input ng-repeat=(index, variable) in variables" type="text"
               my-name="{{ variable.name + '/' + 'myFormName' }}"
               ng-model="variable.name" required />
    ex: <select ng-model="variable.name" ng-options="label in label in {{ variable.options }}"
                my-name="{{ variable.name + index + '/' + 'myFormName' }}"
        </select>
</form>

Note: you can add and index to the string concatenation if you need to serialize perhaps a table of inputs; which is what I did.

app.directive('myName', function(){

  var myNameError = "myName directive error: "

  return {
    restrict:'A', // Declares an Attributes Directive.
    require: 'ngModel', // ngModelController.

    link: function( scope, elem, attrs, ngModel ){
      if( !ngModel ){ return } // no ngModel exists for this element

      // check myName input for proper formatting ex. something/something
      checkInputFormat(attrs);

      var inputName = attrs.myName.match('^\\w+').pop(); // match upto '/'
      assignInputNameToInputModel(inputName, ngModel);

      var formName = attrs.myName.match('\\w+$').pop(); // match after '/'
      findForm(formName, ngModel, scope);
    } // end link
  } // end return

  function checkInputFormat(attrs){
    if( !/\w\/\w/.test(attrs.rsName )){
      throw myNameError + "Formatting should be \"inputName/formName\" but is " + attrs.rsName
    }
  }

  function assignInputNameToInputModel(inputName, ngModel){
    ngModel.$name = inputName
  }

  function addInputNameToForm(formName, ngModel, scope){
    scope[formName][ngModel.$name] = ngModel; return
  }

  function findForm(formName, ngModel, scope){
    if( !scope ){ // ran out of scope before finding scope[formName]
      throw myNameError + "<Form> element named " + formName + " could not be found."
    }

    if( formName in scope){ // found scope[formName]
      addInputNameToForm(formName, ngModel, scope)
      return
    }
    findForm(formName, ngModel, scope.$parent) // recursively search through $parent scopes
  }
});

This should handle many situations where you just don't know where the form will be. Or perhaps you have nested forms, but for some reason you want to attach this input name to two forms up? Well, just pass in the form name you want to attach the input name to.

What I wanted, was a way to assign dynamic values to inputs that I will never know, and then just call $scope.myFormName.$valid.

You can add anything else you wish: more tables more form inputs, nested forms, whatever you want. Just pass the form name you want to validate the inputs against. Then on form submit ask if the $scope.yourFormName.$valid

This will get the name in the ng-repeat to come up seperate in the form validation.

<td>
    <input ng-model="r.QTY" class="span1" name="{{'QTY' + $index}}" ng-pattern="/^[\d]*\.?[\d]*$/" required/>
</td>

But I had trouble getting it to look up in its validation message so I had to use an ng-init to get it to resolve a variable as the object key.

<td>
    <input ng-model="r.QTY" class="span1" ng-init="name = 'QTY' + $index" name="{{name}}" ng-pattern="/^[\d]*\.?[\d]*$/" required/>
    <span class="alert-error" ng-show="form[name].$error.pattern"><strong>Requires a number.</strong></span>
    <span class="alert-error" ng-show="form[name].$error.required"><strong>*Required</strong></span> 

validation is working with ng repeat if I use the following syntax scope.step3Form['item[107][quantity]'].$touched I don't know it's a best practice or the best solution, but it works

<tr ng-repeat="item in items">
   <td>
        <div class="form-group">
            <input type="text" ng-model="item.quantity" name="item[<% item.id%>][quantity]" required="" class="form-control" placeholder = "# of Units" />
            <span ng-show="step3Form.$submitted || step3Form['item[<% item.id %>][quantity]'].$touched">
                <span class="help-block" ng-show="step3Form['item[<% item.id %>][quantity]'].$error.required"> # of Units is required.</span>
            </span>
        </div>
    </td>
</tr>