Self Joining ActiveRecord, Parent_Post_ID and me - ruby-on-rails

Question

So I have a self-joining model defined. Basically a post on a forum, and a parent_post that it belongs to.
class Post < ActiveRecord::Base
has_many :replies, :class_name => "Post"
belongs_to :thread, :class_name => "Post", :foreign_key => "parent_post_id"
end
Which seems fundamentally sound. I created a new RESTful route for the reply action, and an action and view.
Routes:
resources :forums do
resources :posts do
member do
get 'reply'
end
end
end
The view layer and the control action seems to be where I'm getting hosed up.
def reply
#forum = Forum.find(params[:forum_id])
#post = #forum.posts.build
#post.thread = #forum.posts.find(params[:id])
#post.title = "RE: #{#post.thread.title}"
end
def create
#forum = Forum.find(params[:forum_id])
#post = #forum.posts.build(params[:post])
#post.user = current_user
if #post.save
redirect_to forum_post_path(#forum, #post), notice: 'Post was successfully created.'
else
render action: "new"
end
end
And in the view layer I was just trying to use the same scaffold generated form partial I'm using for the standard new and edit actions.
#reply.html.erb
<%= render :partial => 'form' %>
#_form.html.erb
<%= form_for [#forum,#post], :html => { :class => 'form-horizontal' } do |f| %>
<fieldset>
<legend><h1>New Thread</h1></legend>
<div class="control-group">
<%= f.label :title, :class => 'control-label' %>
<div class="controls">
<%= f.text_field :title, :class => 'text_field span9' %>
</div>
</div>
<div class="control-group">
<%= f.label :body, :class => 'control-label' %>
<div class="controls">
<%= f.text_area :body, :class => 'text_area span9' %>
</div>
</div>
<div class="form-actions">
<%= f.submit 'Submit', :class => 'btn btn-primary' %>
<%= link_to 'Cancel', forum_posts_path(#forum), :class => 'btn' %>
</div>
</fieldset>
<% end %>
However, the parent_post_id is getting lost when I'm creating the post and it's getting set to nil. Do I need to create another action? Is there some other way to set the thread? Some third thing?

Answer 1

This will work:
Reply action:
#forum = Forum.find(params[:forum_id])
#post = #forum.posts.build
#post.thread = #forum.posts.find(params[:id])
#post.title = "RE: #{#post.thread.title}"
Then add this to your view
<%= f.hidden_field :parent_post_id, #post.thread.id %>
BTW I question whether you need a custom reply method as opposed to using built-in RESTful methods but this should fix your problem and that wasn't really your question.

Answer 2

add
<%= hidden_field_tag :forum_id , #forum.id %>
to your form

Answer 3

So basically, when you're submitting to the Posts#create action you're submitting a url that looks something like this /forum/1/posts which removes the parent_post_id from the url. Since you're using that parent_post_id to build that url, you need a way to POST with it.
My suggestion is allowing a POST to a reply resource that is nested in the posts resource.
(ie POST /forums/1/posts/1/reply)
So maybe something like this
resources :forums do
resources :posts do
# :show is actually just pointing to a form
resource :reply, :only => [:show, :create],
:controller => 'reply' #otherwise gets routed to 'replies'
end
end
So you would also need a ReplyController but that would basically match your reply method on your post controller with a few changes.
def show
#forum = Forum.find(params[:forum_id])
#post = #forum.posts.find(params[:post_id])
#reply = #forum.posts.build
#reply.thread = #post
#reply.title = "RE: #{#post.thread.title}"
end
def create
#forum = Forum.find(params[:forum_id])
#post = #forum.posts.find(params[:post_id])
#reply = #forum.posts.build(params[:reply])
#reply.thread = #post
#reply.user = current_user
if #reply.save
redirect_to forum_post_path(#forum, #post), notice: 'Reply was successfully created.'
else
render action: "show"
end
end
The biggest problem would be that you would have to abstract your Post fields from your form for block. That's because the url you're trying to POST to is going to be different. But it shouldn't be too bad just doing something like this:
reply/show.html.erb
<%=
form_for #reply, :url => forum_post_reply_path(#forum, #post),
:html => { :class => 'form-horizontal' } do |builder|
%>
<fieldset>
<legend><h1>New Reply</h1></legend>
<%= render "posts/post_fields", :f => builder %>
<div class="form-actions">
<%= builder.submit 'Submit', :class => 'btn btn-primary' %>
<%= link_to 'Cancel', forum_post_path([#forum, #post]), :class => 'btn' %>
</div>
</fieldset>
<% end %>
posts/_form.html.erb
<%= form_for [#forum,#post], :html => { :class => 'form-horizontal' } do |builder| %>
<fieldset>
<legend><h1>New Thread</h1></legend>
<%= render "post_fields", :f => builder %>
<div class="form-actions">
<%= builder.submit 'Submit', :class => 'btn btn-primary' %>
<%= link_to 'Cancel', forum_posts_path(#forum), :class => 'btn' %>
</div>
</fieldset>
<% end %>
posts/_post_fields.html.erb
<div class="control-group">
<%= f.label :title, :class => 'control-label' %>
<div class="controls">
<%= f.text_field :title, :class => 'text_field span9' %>
</div>
</div>
<div class="control-group">
<%= f.label :body, :class => 'control-label' %>
<div class="controls">
<%= f.text_area :body, :class => 'text_area span9' %>
</div>
</div>
Note: There's probably a better way to declare the routes than I have, but I don't really know.