Rails unwanted duplication with the nested_form gem - ruby-on-rails

Question

I'm not sure what is happening here. I've checked everything here but I'm getting this double file upload field:
Even if I use only one field it still renders two images.
_form.html.erb:
<%= nested_form_for #home, :html=>{:multipart => true } do |f| %>
<% if #home.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#home.errors.count, "error") %> prohibited this blog from being saved:</h2>
<ul>
<% #home.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<p>
<%= f.label :body %><br />
<%= f.text_area :body %>
</p>
<p>
<%= f.fields_for :attachments do |attachment_form| %>
<%= attachment_form.file_field :file %>
<br /><br />
<%= attachment_form.link_to_remove "Remove this attachment" %>
<% for attachment in #home.attachments %>
<div class="show_image">
<%= image_tag attachment.file_url(:thumb).to_s %>
</div>
<% end %>
<% end %>
<br /><br />
<%= f.link_to_add "Add attachmnt", :attachments %>
</p>
<br /><br />
<p><%= f.submit %></p>
<br /><br />
<% end %>
Models:
attachment.rb:
class Attachment < ActiveRecord::Base
attr_accessible :description, :file
belongs_to :attachable, :polymorphic => true
mount_uploader :file, FileUploader
end
home.rb:
class Home < ActiveRecord::Base
attr_accessible :body, :attachments_attributes
has_many :attachments, :as => :attachable
accepts_nested_attributes_for :attachments, :allow_destroy => true
end
homes_controller.rb:
class HomesController < ApplicationController
# GET /homes
# GET /homes.json
def index
#homes = Home.all
respond_to do |format|
format.html # index.html.erb
format.json { render :json => #homes }
end
end
# GET /homes/1
# GET /homes/1.json
def show
#home = Home.find(params[:id])
respond_to do |format|
format.html # show.html.erb
format.json { render :json => #home }
end
end
# GET /homes/new
# GET /homes/new.json
def new
#home = Home.new
respond_to do |format|
format.html # new.html.erb
format.json { render :json => #home }
end
end
# GET /homes/1/edit
def edit
#home = Home.find(params[:id])
end
# POST /homes
# POST /homes.json
def create
#home = Home.new(params[:home])
respond_to do |format|
if #home.save
format.html { redirect_to #home, :notice => 'Home was successfully created.' }
format.json { render :json => #home, :status => :created, :location => #home }
else
format.html { render :action => "new" }
format.json { render :json => #home.errors, :status => :unprocessable_entity }
end
end
end
# PUT /homes/1
# PUT /homes/1.json
def update
#home = Home.find(params[:id])
respond_to do |format|
if #home.update_attributes(params[:home])
format.html { redirect_to #home, :notice => 'Home was successfully updated.' }
format.json { head :no_content }
else
format.html { render :action => "edit" }
format.json { render :json => #home.errors, :status => :unprocessable_entity }
end
end
end
# DELETE /homes/1
# DELETE /homes/1.json
def destroy
#home = Home.find(params[:id])
#home.destroy
respond_to do |format|
format.html { redirect_to homes_url }
format.json { head :no_content }
end
end
end
How do I stop this from happening?
Any help with this would be great, I've been looking at this for hours!

Answer 1

My first guess would be bad data created while getting this set up. Maybe there are previous attachments on the Home object that are not being displayed correctly, but still exist in the database. Does the same problem happen if you create a new Home and attempt to add attachments?
The fields_for block is creating a button and a display of each photo for each attachment it's being passed. I think that's why you're seeing the duplication. The fields_for is an iterator on attachments with a duplicate iterator inside it (for attachment in #home.attachments).