Rails: Using form_for multiple times (DOM ids)
You can use :namespace => 'some_unique_prefix' option. In contrast to :index, this will not change the value used in the name attribute.
It's also possible to use an array, e.g. when you have nested forms or different forms that happen to have some fields in common: :namespace => [@product.id, tag.id] or :namespace => [:product, @product.id]
I found the answer myself, one can pass a :index option to form_for. That string will be used in the id and for attributes:
<%= form_for @person, :index => @person.id do |f| %> <%= f.label :name %> <%= f.text_field :name %> <%= f.submit %><% end %>will parse
<form accept-charset="UTF-8" action="/person/11" class="edit_person" id="edit_person_11" method="post"> <!-- Hidden div for csrf removed --><label for="person_11_name">Name</label> <input id="person_11_name" name="person[11][name]" size="30" type="text" /> <input name="commit" type="submit" value="Update Person" /> </form>Notice it'll change the name of the inputs as well.