Rails 3: Multiple Select with has_many through associations

Question

I want to get possibility to select several Categories for one Post with multiple select.

I have next models: Post, Category and PostCategory.

class          


        

Answer 1

As the @post does not have id, the from might not display categories as there is no association. You need to pass do a build on @post something like

 @post = Post.new(:categories => Category.all)