app/views/payforms/_date_select.html.erb
<% form_tag({action: :go, department_id: @department},
{id: 'date_form', class: 'onchange_submit', method: :get} ) do %>
<%= select_tag :date, options_for_select(last_10_dates.map{|d|d.to_s(:long)},
Payform.default_period_date(date, @department).to_s(:long)) %>
<%= submit_tag "Change Date", id: 'submit_date' %>
<% end %>