Validate form using dynamically textarea name - angularjs

Question

I have one validation form using angular. I would like validate forms in ng-repeat using dynamically textarea name. Look on my code:
<div ng-repeat="comment in comments track by $index">
<form name="main.adminArticleReplyForm" novalidate>
<div ng-class="{'has-success':(main.adminArticleReplyForm.commentReply_{{$index}}.$valid), 'has-error':(!main.adminArticleReplyForm.commentReply_{{$index}}.$valid)}">
<textarea name="commentReply_{{$index}}" ng-model="main.commentReply[$index]" required></textarea>
<ul ng-show="(!main.adminArticleReplyForm.commentReply_{{comment.number}}.$pristine && main.adminArticleReplyForm.$error.minlength[0].$viewValue.length)">
<li>You have to add {{10 - main.adminArticleReplyForm.$error.minlength[0].$viewValue.length}} characters</li>
</ul>
<button type="submit">Submit</button>
</div>
</form>
</div>
And my problems:
If you check {{main.adminArticleReplyForm}} commentReply_{{$index}} is always last $index in ng-repeat for example if are 4 comments in array in form always is commentReply_4, but textareas name in DOM are correct.
I have to use controller as, in my case main, but if I remove main from form name, everything works nice.
Summary, {{main.adminArticleReplyForm}} is validate only for last $index in ng-repeat previously $indexes are ignored
Here is fiddle for look that every commentReply_{{$index}} is commentReply_2 https://jsfiddle.net/8od25zhb/5/

Answer 1

Description
you don't need to track it by index that make repeat last index
you don't need to add main to the form, because form is in repeat so make it unique, if you want to have just one form make it out of repeat; so we just use comment.adminArticleReplyForm as form name, and just main.comments used main from controller.
by this 2 step your forms validate just the textarea which inside it.
you don't need create unique names and models for textarea, because you create them inside ng-repeat and all are unique.
<div ng-app="app" ng-controller="ctrl as main">
<div ng-repeat="comment in main.comments">
<form name="comment.adminArticleReplyForm" novalidate>
{{comment.adminArticleReplyForm}}
<div>
<textarea name="commentReply" ng-model="comment.commentReply" required></textarea>
<button type="submit">Submit</button>
</div>
</form>
<hr/>
</div>
</div>

Answer 2

Since, AngularJS default validation works on hierarchy of element names to detect their state thus, the name of textarea you have used is commentReply_{{$index}} with a underscore but you are using commentReply{{comment.number}} in the validation expressions. So make it look with a underscore and it will work. So, final code will look something like this:
<div ng-repeat="comment in comments track by $index">
<form name="main.adminArticleReplyForm" novalidate>
<div ng-class="{'has-success':(main.adminArticleReplyForm.commentReply_{{$index}}.$valid), 'has-error':(!main.adminArticleReplyForm.commentReply_{{$index}}.$valid)}">
<textarea name="commentReply_{{$index}}" ng-model="main.commentReply[$index]" required></textarea>
<ul ng-show="(!main.adminArticleReplyForm.commentReply_{{comment.number}}.$pristine && main.adminArticleReplyForm.$error.minlength[0].$viewValue.length)">
<li>You have to add {{10 - main.adminArticleReplyForm.$error.minlength[0].$viewValue.length}} characters</li>
</ul>
<button type="submit">Submit</button>
</div>
</form>
</div>