Configuring Rails 3 + Polymorphic Image model + Paperclip and Amazon S3, No errors, but nothing uploading - ruby-on-rails-3

Question

I suspect the problem lies in the way I am creating the polymorphic image attribute. I am using fields_for in the form.
In this case a user can create a post and add an image using paperclip, storing it with S3.
I am using a polymorphic image model "post_image":
class PostImage < ActiveRecord::Base
belongs_to :imageable, :polymorphic => true
#.merge(PAPERCLIP_OPS)
has_attached_file :image, :styles => { :medium => "200x200>", :thumb => "50x50>" },
:storage => :s3,
:s3_credentials => "#{Rails.root}/config/s3.yml",
:path => "/:style/:id/:filename",
:bucket => "zounds-dev"
validates_attachment_presence :image
validates_attachment_size :image, :less_than => 5.megabytes
end
Post Model:
class Post < ActiveRecord::Base
has_many :post_images, :as => :imageable, :dependent => :destroy
.
.
.
accepts_nested_attributes_for :post_images, :reject_if => lambda { |t| t[:post_image].nil?}, :allow_destroy => true
end
New Post Form:
=form_for( setup_post(#post,current_user), :html => { :multipart => true}) do |f|
%dl
=f.fields_for :post_images do |ff|
=ff.file_field :image
%dt.field=f.label :name
%dd.field=f.text_field :name
%dt.field=f.label :description
%dd.field=f.text_area :description
=f.fields_for :user do |u|
=render "user_fields", :f => u
=f.fields_for :assignments do |ff|
=ff.check_box :_destroy, {:checked => ff.object.persisted?}, '0','1'
=ff.label :_destroy, ff.object.group.name
=ff.hidden_field :group_id
.action=f.submit "Save Post"
The setup_post helper method used in the Post form_for: (the groups stuff isn't relevant here)
def setup_post(post, current_user)
groups = current_user.groups_as_owner + current_user.groups_as_member
(groups - post.groups).each do |group|
post.assignments.build(:group => group)
end
post.assignments.sort_by {|x| x.group.name }
post_image = post.post_images.build
post
end
Post controller:
def new
#user = User.find(params[:user_id])
# #post = #user.posts.build
#post = Post.new
respond_to do |format|
format.html # new.html.erb
format.xml { render :xml => #post }
end
end
def create
#user = current_user
#post = #user.posts.build(params[:post])
.
.
.
end
I suspect the problem is that I am using fields_for for the post_image attribute, but I've looked all over and can't figure out what the proper way to implement a polymorphic nested image attribute is.
I also did the s3sh amazon s3 console thing, and although I couldn't upload an image because I couldn't figure out how to pass in the right image path to the open() function, I connected to S3. My s3.yml file is set up correctly as well.
Thanks yall,
Brian

Answer 1

The issue was with the reject_if in accepts_nested_attributes for the Post model
accepts_nested_attributes_for :post_images, :reject_if => lambda { |t| t[:post_image].nil?}, :allow_destroy => true
commenting it out fixed the issue.