EasyPresenter

Access all view methods from model instances in Ruby on Rails.

Usage

Easy

gem 'easy_presenter'

Given a model User

# app/presenters/user_presenter.rb
module UserPresenter
  # Separate view of the model in the presenter, even if it's a `String`. Leave data manipulation in the model.
  def full_name
    "#{first_name} #{last_name}"
  end

  # Quick link to the `User`
  def link
    link_to full_name, user_path(self)
  end

  # Using a module, so you must do this to add class methods
  module ClassMethods
    # String of all full names separated by commas
    def full_names
        all.map(&:full_name).join(", ")
    end
  end
end

Access your presenter methods in a view:

<!-- app/views/users/index.html.erb -->
<% User.all.each do |user| %>
  <%= user.link %><br>
<% end %>

Or a helper:

# app/helpers/users_helper.rb
module UsersHelper
  def full_names_in_div
    content_tag :div, User.full_names
  end
end

Supported ORMs

ActiveRecord, Mongoid, you may add support to an ORM at the bottom of lib/easy_presenter.rb and send in a pull request if you wish.

Advanced

Instance Variables

You can get controller instance variables using controller_get(:@instance_variable), which calls Object#instance_variable_get(p1) on the controller.

Non-Supported ORM Models

You may include the following modules to add EasyPresenter to other classes.

EasyPresenter::Base - add access to view methods
EasyPresenter - Give access to the ClassNamePresenter class that has access to view methods. Subclasses will also have the same effect.

To add access to view methods to all instances or subclasses (such as an ORM).

# config/initializers/add_presenter_to_orm.rb
# Find the base or shared class, for `ActiveRecord` it's `ActiveRecord::Base` and `Mongoid` it's `Mongoid::Document`
Orm::BaseClass.send :include, EasyPresenter

For all instances of a basic class.

# app/models/non_database_model.rb
class NonDatabaseModel
    include EasyPresenter
end

# app/presenters/non_database_model_presenter.rb
module NonDatabaseModelPresenter
    ...

    module ClassMethods
        ...
    end
end

For all instances of a basic class without need of a ClassNamePresenter class.

# app/models/some_view_object.rb
class SomeViewObject
    include EasyPresenter::Base

    def random_link
        link_to "random", "http://www.random.com"
    end
end

Credits

Extracted out of Placemark.

Contribution

Feel free to fork, post issues or send any pull requests. Thanks.

easy_presenter

Development

Runtime