Rails Associations (belongs_to, has_many) can't save 2 ids in table with a create method (user, post, comment)

Trying to write a basic "blog-like" app in rails 3, I'm stuck with associations. I need the create method save the post_id as well as the user_id in the comment table (which I need in order to retrive all comments written by a user in order to display it)

The app has users (authentication - devise), posts (posted by users - but I'm not sure it matters in my case) and comments (on the posts, posted by users).

the comment table has a post_id, a body, and also a user_id

Associations:

has_many :comments (In the Post model)
belongs_to :post (In the Comment model)
belongs_to :user (In the Comment model)
has_many :comments (In the User model)

the routes:

resources :posts do
  resources :comments
end

resources :users do
  resources :comments
end

The comment post form displayed on the posts show view: (posts/show.html.erb)

<% form_for [@post, Comment.new] do |f| %>
  <%= f.label :body %>
  <%= f.text_area :body %>
  <%= f.submit %>
<% end %>

and finally, the create method in the comments controller:

A.) If I write this a post_id is written in the database

def create
  @post = Post.find(params[:post_id])
  @comment = @post.comments.create!(params[:comment])
  redirect_to @post
end

B.) If I write this a user_id is written...

def create
  @user = current_user
  @comment = @user.comments.create!(params[:comment])
  redirect_to @post
end

I tried:

@comment = @post.comments.create!(params[:comment].merge(:user => current_user))

But it doesn't work.. H开发者_开发技巧ow can I write a method which save the user_id and the post_id ? Did I have also to do some change in the comment post form (something like <% form_for [@post, @user, Comment.new] do |f| %> ?)

Thank you!

---

To set up something very similar, I've used the following form:

<%= form_for [:place, @comment] do |f| %>
  #form fields here
<%= end %>

Then in the comments controller:

def create
  @post = Post.find(params[:post_id])
  @comment = @post.comments.build(params[:comment])
  @comment.user = User.find(current_user.id)

  respond_to do |format|
  if @comment.save
    format.html { redirect_to(@comment.post, :notice => 'Comment was successfully created.') }
  else
    format.html { render :action => "new" }
  end
end

end

That should build the associations properly hopefully! Just as an aside, do you mean for comments to be nested under :users in your routes? If you just want to display all the user's comments on a profile page, you could do something like:

<p>
  <b>Comments</b>
  <% if @user.comments.empty? %>
    No comments to display yet...
  <% else %>
    <% @user.comments.each do |comment| %>
      <p>
      <%= link_to "#{comment.post.title}", post_path(comment.post_id) %>, <%= comment.created_at %>
      <%= simple_format comment.content %>
      </p>
    <% end %>
  <% end %>
</p>

Hope some of that helps!