Commentable¶ ↑

This is a really simple ActiveRecord plugin that allows models to be commented.

Commentable is tightly coupled to an User model. If you don’t have it, there’s no game for you here.

gem install commentable

First, you’ll have to create the comments table. Run rails generate migration create_comments and add the following code:

class CreateComments < ActiveRecord::Migration
  def self.up
    create_table :comments do |t|
      t.text :body, :formatted_body
      t.references :commentable, :polymorphic => true
      t.references :user
      t.timestamps
    end

    add_index :comments, [:commentable_id, :commentable_type], :name => "index_on_commentable"
    add_index :comments, [:commentable_id, :commentable_type, :user_id], :name => "index_on_commentable_and_user"
  end

  def self.down
    drop_table :comments
  end
end

Run rake db:migrate to apply this new migration.

Now, add the commentable macro to all models that can be commented.

class Task < ActiveRecord::Base
  commentable
end

This will create an association called comments. You can now create comments like any ActiveRecord model.

comment = @task.comments.create(:body => "Awesome job!", :user => @user)

There’s a shortcut for that.

comment = @task.add_comment(:body => "Awesome job!", :user => @user)

You can have formatted comments. This is specially useful if you want to provide Markdown support, for instance. Just use the :format option passing any object that responds to the call method. The block’s return will be used as the formatted_body attribute.

class Task < ActiveRecord::Base
  commentable :format => proc {|comment| Redcarpet.new(comment.body.to_s).to_html}
end

Final note: remember to add a comments_count column to every single model that will be commentable. This is required by the Comment model.

• Nando Vieira (nandovieira.com.br)

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