isolate-form

An Angular directive for nested forms that prevents $invalid from propagating, allowing a nested form to be invalid without affecting its parent's validity.

Code originally written by 91K00, as seen here and here.

Usage:

 <form name="parent">
    <input type="text" ng-model="outside"/>
    <ng-form name="subform" isolate-form>
        <input type="text" ng-model="inside"/>
    </ng-form>
</form>
 

Example: http://jsfiddle.net/gikoo/qNrFX/