AngularJS dynamic form field validation

Question

I am trying to validate some form fields which are given to me from a backend endpoint...

So basically the input elements are dynamically created inside a ng-repeat. Therefore, the input attributes are also dynamically added, such as the type, name, etc...

However because the name attribute is dynamically added, when I try to validate it, like this, for example:

myForm.elName.$valid

It doesn't return anything because at this point, it doesn't know what elName is.

I created a jsFiddle to demonstrate the problem: http://jsfiddle.net/peduarte/HB7LU/1889/

Any help or advice will be much appreciated!

FANX.

EDIT:
I've been referring to this AWESOME documentation: http://docs.angularjs.org/api/ng.directive:input.email

Please, develop. Why do you regret every seconds of angularJS? — Ant
– Ant, Commented Mar 20, 2014 at 6:36
This is what you are looking for stackoverflow.com/questions/27071413/… — SoEzPz
– SoEzPz, Commented Nov 21, 2014 at 22:56

Community · Accepted Answer · 2017-05-23 12:09:14Z

Try my custom directive:

myApp.directive("dynamicName",function($compile){
  return {
      restrict:"A",
      terminal:true,
      priority:1000,
      link:function(scope,element,attrs){
          element.attr('name', scope.$eval(attrs.dynamicName));
          element.removeAttr("dynamic-name");
          $compile(element)(scope);
      }
   };
});

Use it:

<input dynamic-name="field.name"
       type="{{ field.type }}"
       placeholder="{{ field.name }}"
       ng-model="field.value"
       required>

DEMO

Explanation of the problem:

By default, input elements using ngModelController (ng-model) call FormController.$addControl when they are linked to register itself and expose a property on the FormController with the name property of the input which is {{ field.name }} in this case. Therefore, even though the control is registered but you don't have exposed properties on FormController with named email, firstName, you only have {{ field.name }} referencing the last input item

Explanation of the solution:

In this solution, I created a custom directive to replace the {{ field.name }} with the correct name at runtime.

For more information why I have to use terminal:true, and priority:1000, check out this discussion: Add directives from directive in AngularJS

A isolated scope can be used instead of scope.$eval: scope: { dynamicName: '=' } in the directive configuration then simply scope.dynamicName inside link.
@Hugo Wood: I don't think we need isolate scope here. The purpose of this directive is to modify the current element based on current scope. Using current scope is more appropriate IMO.
can I loop through error messages dynamically ? they are hardcoded in the demo
@sisimh: yes, just use javascript bracket notation: {{ myForm[formFields[0].name].$valid }}: jsfiddle.net/3qu3tu6f
thank you for ur reply @KhanhTO , actually i am thinking of returning the validation error from the directive it self , in that case how can I concat form name with the error fields like what u did except that i dont have "myForm" hardcoded

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