Easy-peasy form objects

1. Puts the following code into controllers → concerns → application_shape.rb:

module ApplicationShape
  extend ActiveSupport::Concern

  module ClassMethods
    delegate :model_name, to: :superclass
    delegate :name, to: :superclass
  end
end

2. Use it like this:

class ModerationArticleShape < Article
  include ApplicationShape

  validates :category, presence: true
end

def update
  @article = ModerationArticleShape.find(params[:id])
  if @article.update(params.require(:article))
    redirect_to moderation_articles_path
  else
    render 'edit'
  end
end