app/views/admin/events/_form.html.erb
<%= form_for [:admin, @event], :remote => true do |f| %>
<%= error_messages_for(@event) %>
<label>Designation</label>
<%= f.select :designation_id,
options_from_collection_for_select(@designations, :id, :name, @event && @event.designation_id)
%><br />
<label>Name</label><%= f.text_field :name %><br />
<label>Effective from</label>
<%= f.text_field :effective_at, :class => "datepicker",
:value => @event.effective_at_formatted
%>
<label>URL</label><%= f.text_area :url %><br />
<label>Description</label><%= f.text_area :description %><br />
<% end %>