/classic_presenter

A simple Presenter Pattern for Rails Applications

Primary LanguageRuby

Classic Presenter ↑

Presenter Pattern for Rails Applications

Installation ↑

gem install classic_presenter

Usage ↑

  • In your Gemfile you should set:

    gem 'classic_presenter'

  • Create a simple ActiveRecord class that you want to present:

    class Product < ActiveRecord::Base
end

  • Create a presenter class inheriting from ClassicPresenter::Base:

    class ProductPresenter < ClassicPresenter::Base
  def display_name
      if user
        context.content_tag :strong, name
      else
      context.link_to name, context.product_path
    end
  end

  def display_description
    context.render "products/description", :product => self
  end
end

  • In your view, show.html.erb for example, you can present your Product object using this syntax:

    <% present ProductPresenter, @product, :user => current_user do |presenter| %>
<%= presenter.display_name %>
<%= presenter.display_description %>
<% end %>

Additional details ↑

  • We can pass many objects to the presenter. In this example we are using :user => current_user and current_user is a helper that returns a User that is logged in. But we can use this for example:

    <% present ProductPresenter, @product, :foo => "bar", :bar => "foo" do |presenter| %>

  • Since ClassicPresenter::Base is a Decorator, it implements the “transparent interface” requirements of the Gang of Four’s definition. This means that when we call some method in ProductPresenter, it will be delegated to the decorated object (in this case Product), like this:

    #products_controller.rb
@product = ProductPresenter.new(Product.find(params[:id]))

#show.html.erb
<%= @product.name %>
<%= @product.display_name %>