AR Associations - use the setters

new_gist_file.md

The better way to make this association is to use the ActiveRecord setters provided by your belongs_to association.

Anti-pattern

post '/posts' do
  @post = Post.new(params[:post)
  @post.author_id = author.id
  if @post.save
    redirect "/posts"
  else
    render :new, locals: { messages: [ "There was an error!", @post.errors.full_messages ] }
  end
end

Anti-Anti-Pattern:

post '/posts' do
  @post = current_user.posts.build(params[:post)
  if @post.save
    redirect "/posts"
  else
    render :new, locals: { messages: [ "There was an error!", @post.errors.full_messages ] }
  end

Always use the getters/setters provided. Your controller should not be reaching into your models and playing with the *_id attributes. It should be utilizing the getters and setters AR associations make for you.