Custom attributes for Flask WTForms

I develop website on Flask and AngularJS. I need to send a form whith AJAX using AngularJS but it requires a custom attribute for input field. For example I have a form in Jinja2 template:

<form method="post" action="/">
    {{ form.hidden_tag() }}
    {{ form.name(placeholder="Name") }}
</form>

So how can I add an attribute from AngularJS lets say "ng-model" for my "name" field?

Thanks for your help!