app/views/district/users/_staff_assignments.erb
<span class="awesome_nested">
<div id="user_staff_assignments" class="items">
<%= form.nested_fields_for :staff_assignments do |staff_assignment| %>
<%= render :partial => 'staff_assignment',:object => staff_assignment %>
<% end %>
</div>
<div class="form_row">
<%= link_to "Add a staff assignment","#", :class => "add" %>
</div>
</span>