Customer
<%= select 'coitem', 'customer_id', Customer.find(:all).collect {|c| [c.name.to_s, c.id] } %>

Rentable
<%= select 'coitem', 'rentable_id', Rentable.find(:all).collect {|r| [r.title.to_s, r.id] } %>

Out date
<%= date_select 'coitem', 'out_date' %>

Due date
<%= date_select 'coitem', 'due_date' %>