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

Final solution to organize categories in your posts, I hope it will be useful.

To use multiple we need select_tag:

<%= select_tag "categories", options_from_collection_for_select(Categories.all, 'id', 'name'), :multiple => true %>

Or f.select (many thanks to Tigraine and Brent!), it's more elegant way:

<%= f.select :categories, Category.all.collect {|x| [x.name, x.id]}, {}, :multiple => true %>

In create action of our controller we need:

def create
   @post = Post.new(params[:post])

if @post.save

  params[:categories].each do |categories|
     categories = PostCategory.new(:category_id => categories, :post_id => @post.id)
     if categories.valid?
       categories.save
     else
       @errors += categories.errors
     end
  end
  redirect_to root_url, :notice => "Bingo!"
else
  render "new"
end
end