Rendering partial results in syntax error

Question

Currently working on nested forms with the following railscast http://railscasts.com/episodes/196-nested-model-form-revised

I have an Opportunity model,

class Opportunity < ActiveRecord::Base
    has_many :headings
    accepts_nested_attributes_for :headings
end

a Heading model

class Heading < ActiveRecord::Base
    belongs_to :opportunity
    has_many :subheadings
    accepts_nested_attributes_for :subheadings
end

and a Subheading model

class Subheading < ActiveRecord::Base
    belongs_to :heading
end

Right now I am just working on the view for the new action for the Opportunity model.

<h1>Add an opportunity</h1>
<%= form_for(@opportunity, :html => {:role => 'form'}) do |f| %>
    <%= f.fields_for :headings do |builder| %>
        <%= render 'heading_fields', f: builder %>
    <% end %>
    <%= link_to_add_fields "Add heading", f, :headings %>
    <%= f.submit %>
<% end %>

And the _heading_fields.html.erb partial:

<fieldset>
    <%= f.label :title, "Heading" %>
    <%= f.text_field :title %>
    <%= f.hidden_field :_destroy %>
    <%= link_to "Remove section", '#', class: "remove_fields" %>
    <%= link_to_add_fields "Add section", f, :subheadings %>
</fieldset>

And finally the link_to_add_fields method in the application helper:

def link_to_add_fields(name, f, association)
    new_object = f.object.send(association).klass.new
    id = new_object.object_id
    fields = f.fields_for(association, new_object, child_index: id) do |builder|
        render(association.to_s.singularize + "_fields", f: builder)
    end
    link_to(name, '#', class: "add_fields", data: {id: id, fields: fields.gsub("\n", "")})
end

Now I am receiving the following error for the render call in the link_to_add_fields function:

syntax error, unexpected tIDENTIFIER, expecting keyword_end

It seems to have something to do with the underscore in the name of the partial being rendered in the link_to_add_fields method as it goes away when the underscore is not present.

Greatly appreciate any help at solving this headache!

Answer 1

Debug

As mentioned in the comments, you're basically going to have an issue with the closing of your loops - Rails is expecting an end call, but you've set an identifier of sorts instead.

Having looked through your code, I cannot see where the issue might be, so I'll give you some details on how I'd debug it:

I would remove any elements which I would presume would be causing the issue, until I got it to work

For example, I would begin by replacing the def link_to_add_fields(name, f, association) with a piece of demo content:

def link_to_add_fields(name, f, association)
    "test"
end

If this outputs the correct string, it means the error is inside this method (which I'm guessing anyway). If this was the case, I would then try this:

def link_to_add_fields(name, f, association)
    new_object = f.object.send(association).klass.new
    id = new_object.object_id
    fields = "test"
    link_to(name, '#', class: "add_fields", data: {id: id, fields: fields})
end

If this works, it means the problem is likely going to be with the f.fields_for loop which you're using. Although this is just my guess, it's basically how I'd debug - sequentially remove things until it actually works

---

Fields

If you're looking to add fields dynamically to your form, you may wish to use the cocoon gem. The Railscast you're using is firstly a little out of date, and only allows you to add single fields to your form

The "right" way to do it is to use an ajax method, which I detail here

There's a very good site I found which showed you how to do it, but the site has since gone offline. Anyway, I'll explain it for you here:

#config/routes.rb
resources :controller do
   collection do
      get :add_field
   end
end

This gives you a route to send ajax requests to:

Controller

#app/views/controller/form.html.erb
<%= form_for @model do |f| %>
   <%= render partial: "fields", locals: { builder: f } %>
   <%= link_to "Add Field", controller_add_field_path, id: "add_field", remote: true %>
   <%= f.submit "test" %>
<% end %>

#app/views/controllers/your_controller.rb
Class YourController < ActiveRecord::Base
   def add_field
      @model = Model.new
      @model.association.build
      render "add_field", layout: false
   end
end

Views

Now you need to render the add_field view, with the fields_for partial

#app/views/controller/_form.html.erb
<%= form_for @model do |f| %>
    <%= render partial: "fields", locals: { builder: f } %>
<% end %>


#app/views/controller/_fields.html.erb
<%= f.fields_for :association, child_index: Time.now.to_i do |a| %>
    <%= a.text_feld :your_fields %>
<% end %>

JQuery

All you need to do then is create a way to fetch the new fields:

#app/assets/javascripts/application.js.coffee
$ ->
  $(document).on "ajax:success", "#add_field", (data) ->
       el_to_add = $(data).html()
       $('#new_form').append(el_to_add)