cocoon gem not passing parameters - ruby-on-rails

Question

So although I have used cocoon successfully before, I'm still relatively new and for whatever reason can't seem to get it to pass through the parameters (I've tried with two different applications and on fedora 22 and mac 10.10.4).
For context I've been using the standard rails forms in .erb and have both :post and :post_items which only currently have a description. I'm using cocoon 1.2.6.
So in application.js I have
//= require cocoon
in post.rb
class Post < ActiveRecord::Base
has_many :post_items
accepts_nested_attributes_for :post_items, :reject_if => :all_blank, :allow_destroy => true
validates :title, :post_items, presence: true
validates :title, length: {maximum: 255}
end
in post_item.rb
class PostItem < ActiveRecord::Base
belongs_to :post
end
and my relevant controllers are (posts_controller.rb):
def index
#post = Post.new
end
def create
params[:post][:ip_address] = request.remote_ip
#post = Post.create(post_params)
if #post.save
flash[:success] = "Your post was successfully created"
redirect_to #post
else
flash[:failure] = "There was an error saving your post"
render 'index'
end
end
private
def find_post
#post = Post.find(params[:id])
end
def post_params
params.require(:post).permit(:title, :tags, :hits, :ip_address, post_items_attributes: [:id, :description, :_destroy])
end
And finally in my views I have (_form.html.erb)
<%= form_for #post, html: {multipart: true} do |f| %>
<% if #post.errors.any? %>
<p>There were <%= #post.errors.count %> errors</p>
<% #post.errors.full_messages.each do |msg| %>
<p><%= msg %></p>
<% end %>
<% end %>
<!-- a bunch of fields here -->
<div class="six columns">
<h3>Add images</h3>
<div id="post_items">
<% f.fields_for :post_items do |post_item| %>
<%= render 'post_item_fields', f: post_item %>
<% end %>
<div class="links">
<%= link_to_add_association 'Add Image', f, :post_items, class: "add-button" %>
</div>
</div>
<%= f.button :submit, class: "button submit-button" %>
<% end %>
and lastly _post_item_fields.html.erb
<div class="nested-fields">
<div class="field">
<%= f.label :description %>
<%= f.text_area :description %>
</div>
<%= link_to_remove_association "Remove", f %>
</div>
There are CSS files that modify the html but I have no js other than what's automatically built. I've literally been stuck on this problem for days now and I can't figure out what's wrong. I have tried the post.rb without the validates code but it still doesn't work.
The only lead I have is that when you print out the parameters it has already dropped the post_items parameters and for the life of me I can't figure out why.
Thanks for the help!
EDIT: for the sake of information I've added my migrations.
in db/migrate/20150722191917_create_post_items.rb
class CreatePostItems < ActiveRecord::Migration
def change
create_table :post_items do |t|
t.string :description
t.belongs_to :post, index: true, foreign_key: true
end
end
end
and in db/migrate/20150722173629_create_posts.rb
class CreatePosts < ActiveRecord::Migration
def change
create_table :posts do |t|
t.string :title
t.string :tags
t.integer :hits, null: false, default: 0
t.string :ip_address
t.timestamps null: false
end
add_index :posts, :ip_address
end
end
Also if it matters I didn't use scaffold when generating them

Answer 1

Well I think I finally figured out what's wrong (although I don't really understand what we're supposed to do to get around it) is that once I got rid of div class="six columns" it worked, so apparently that was interfering with the cocoon gems ability to parse the html.
Thanks everyone for all the help!
EDIT: to clarify I had to change _form.html.erb to:
<%= form_for #post, html: {multipart: true} do |f| %>
<% if #post.errors.any? %>
<p>There were <%= #post.errors.count %> errors</p>
<% #post.errors.full_messages.each do |msg| %>
<p><%= msg %></p>
<% end %>
<% end %>
<!-- a bunch of fields here -->
<h3>Add images</h3>
<div id="post_items">
<% f.fields_for :post_items do |post_item| %>
<%= render 'post_item_fields', f: post_item %>
<% end %>
<div class="links">
<%= link_to_add_association 'Add Image', f, :post_items, class: "add-button" %>
</div>
</div>
<%= f.button :submit, class: "button submit-button" %>
<% end %>
So I guess it was a little my fault as the error would have been easier to spot if I had used the full html instead of parsing it for the cocoon-relevant bits but there it is regardless. (basically the moral of this story is that you can't have div's inside of the form)