Rails 3 + Ajax: how to access my local form builder instance
Can you use fields_for in your partial, and pass the @object to it? That way you don't need to pass a form builder?
partial:
<%= fields_for object do |f| %> f.text_field :field_name<% end %>$('#info').html("<%= escape_javascript(render 'my_second_fields_partial', object: @object) %>
Many thanks to @flyfish, his answer helped me solved how to do ajax with nested attributes. I took @flynfish answer and tweeked it for my situation:
<%= fields_for object do |f| %> <%= f.fields nested_object, child_index: Time.now.to_i do |builder| %><% end %>$('#info').html("<%= escape_javascript(render 'my_second_fields_partial', object: @object), nested_object: @nested_object %>
The child_index is important for without it your params hash will build with [0] and will then overlay any other records built with the initial fields_for which starts at zero and increments from there.