Rails ERB template for http://jsfiddle.net/tatejohnson/vLhNb/. Adding and removing children to a Rails nested form with AngularJS.

new.html.erb

<h1>New Plan</h1>
<div ng-app>
  <%= form_for @plan do |form| %>
    <div ng-controller="PollCtrl" ng-init="polls = <%= @plan.polls.to_json %>">
      <div ng-repeat="poll in polls">
        <%= form.fields_for :polls, Poll.new, child_index: '{{$index}}' do |poll_form| %>
          <%= poll_form.text_field :title, id: 'plan_poll_{{$index}}', value: '{{poll.title}}' %>
        <% end %>
        <a href="#" ng-click="remove($index)" ng-show="isRemovable()">Remove</a>
      </div>
      <a href="#" ng-click="add()">Add</a>
    </div>
  <% end %>
</div>

You need to set an id on the text field, otherwise all your text fields will have plan_polls_attributes____index___title as their id. If you don't care, then you can omit it.