Nested Routes and Forms in Rails 2.0

If you’re doing a form post to a nested resource, like creating a comment under
/posts/1/comments/
with a route like
map.resources :posts do |post|
post.resources :comments
end

you have to account for that when you’re creating a form, you can’t just send it to the comment and hope everything will work out.

It took me a little time to find this, so I’m posting it in hopes of making someone else’s day easier. What I had to do was
form_for([@post,@comment])
and now everything is happy again.