Model Validation with Multiple Models and Good MVC Design

1. Model Validation With Multiple Controllers Involved I have a Posts controller and model and a Comments controller and model. Posts has a show method and a corresponding view that shows a post and its associated comments, which are rendered with a partial from comments. Another partial from comments is used to allow the user to add their comment to the page.

Problem: If a user tries to add a new comment but it fails the comment model validation, how do I get back to the show page from posts and display the model validation error for the new comment?

views/posts/show.rhtml #spit out the details of the post ... #render the existing comments and let a user make a new one <h2>Comments</h2> <%= render :partial => "comments/comment", :collection => @post.comments %> <%= render :partial => "comments/new"%>

controllers/comments_controller.rb #new method unnecessary because the "comments/new" partial never calls it? def new   @comment = end

def create   @comment =[:comment])   if     redirect_to :controller => "posts", :action => "show", :id =>   else     #we're over in the comments controller - how do we get our data validation errors from the     #comments model back over to the show page of posts?     render :controller => "posts", :action => "show" end

2. Good MVC Design OK so for my little blog app at first I had just one controller, blog, and just kept adding methods there like add_post, add_comment, etc. It seemed like maybe that was a bad idea so I decided to use three controllers instead of one: blog, posts, and comments. Blog would be light-weight and not have to care about the details of posts or comments. But then I ran into the problem described above.

What would be the most natural way to structure this kind of thing with MVC, one blog controller with double-barelled methods like add_post, add_comment etc. or a bunch of controllers like posts, comments, etc. that do all the heavy lifting?

Thanks, Yink