Question

I am creating a nested form and using Ryan Bates Railscast. I am creating a typical form that uses a partial.

= form_for(@project, :html => { :class => 'addProjectForm' }) do |f|
  ...
  %p
    = f.fields_for :crew_members do |crew|
      #fields
      = render 'crew_member_fields', :m => crew
      = link_to_add_fields "Add Crew Members", f, :crew_members
  %p

I then a call a helper class to be able to clone the “fields” class and add it to my form.

module ProjectsHelper
  def link_to_add_fields(name, f, association)
    new_object = f.object.class.reflect_on_association(association).klass.new
    fields = f.fields_for(association, new_object, :child_index => "new_#{association}") do |builder|
      render(association.to_s.singularize + "_fields", :f => builder)
    end
    link_to_function(name, h("add_fields(this, \"#{association}\", \"#{escape_javascript(fields)}\")"))
  end
end

The helper class then calls a javascript function to handle the details.

function add_fields(link, association, content) {
        var new_id = new Date().getTime();
        var regexp = new RegExp("new_" + association, "g");
        $(link).parent().before(content.replace(regexp, new_id));
}

My issue is when I add the

= link_to_add_fields "Add Crew Members", f, :crew_members

line, I get the error

undefined local variable or method `m' for #<#<Class:0xa763964>:0xa761588>

    Extracted source (around line #1):

    1: = m.label "Crew Member Name"
    2: = m.label "Crew Member Role"
    3: %br
    4: = m.text_field :name

This makes it seem like the partial is not getting the builder variable, but if I do not have the

= link_to_add_fields "Add Crew Members", f, :crew_members

line, then the partial displays just fine. I am confused on how to debug next. Sorry for the long post, but I want you to have all the information. Thanks for the help.

Answer 1

I think you have a typo in the helper.

module ProjectsHelper
  def link_to_add_fields(name, f, association)
    new_object = f.object.class.reflect_on_association(association).klass.new
    fields = f.fields_for(association, new_object, :child_index => "new_#{association}") do |builder|
      render(association.to_s.singularize + "_fields", :f => builder)
    end
    link_to_function(name, h("add_fields(this, \"#{association}\", \"#{escape_javascript(fields)}\")"))
  end
end

render(association.to_s.singularize + "_fields", :f => builder) should be
render(association.to_s.singularize + "_fields", :m => builder)