Railsfields_for枚举ID

Question

If I have a standard fields_for method such as:

<%= f.fields_for :exptypes do |builder| %>
    <%= render 'exptype_fields', :f => builder %>
<% end %>

Is there such a way to get:

<%= f.fields_for :exptypes do |builder, i| %>
    <%= render 'exptype_fields', :f => builder, :i => i %>
<% end %>

So that a unique number ( i ) is passed to the form?

What I want to do is make unique div tags inside partials so I can run javascript on specific partials in the code.

Answer 1

You're in luck - Rails does this already, automatically. From http://guides.rubyonrails.org/layouts_and_rendering.html under 3.4.6 Local Variables

Rails also makes a counter variable available within a partial called by the collection, named after the member of the collection followed by _counter. For example, if you're rendering @products, within the partial you can refer to product_counter to tell you how many times the partial has been rendered. This does not work in conjunction with the as: :value option.

In your case, this is probably going to be exptype_fields_counter .