how to get the index of the element passed to the render view ?

rubyonrails-talk
1

I am displaying a collection of expenses in a form

the view in which the fom is displayed : ...         = simple_form_for(@project, :html => {:class => 'form-stacked' }) do |f|           - unless @project.expenses.count > 0             No expenses           - else             #expenses               = f.fields_for :expenses do |f|                 = render "backoffice/projects/expense_fields", :f => f         .clearfix

and the expense_fields partial is :

.row   = f.input :label, :wrapper => :nolabel, :input_html => { :class => "span3" }

I would like to test when the first expense item is displayed :

.row         - "if first expense.. test             = f.input :label, :input_html => { :class => "span3" } # use the standard wrapper with labels         - else       = f.input :label, :wrapper => :nolabel, :input_html => { :class => "span3" } # no label wrapper

is there any way to do it ?

thanks for your feedback