Presenters

A simple presenter pattern for ruby. It can work in rails. This is based on Presenters in Rails

Installation

Add this line to your application's Gemfile:

gem 'presenters'

And then execute:

bundle

Or install it yourself as:

gem install presenters

For rails, add this config in config/application.rb

config.autoload_paths += %W(#{config.root}/presenters)

And you can put presenters in app/presenters

Usage

Create presenter class

Assume you have a class named Post, you can create PostPresenter.

class PostPresenter < Presenter
  def title
    super || 'No Title'
  end
end

And you can wrap object like this:

post = Post.new :title => nil, :content => "My Content"
presenter = PostPresenter.new post
presenter.title # "No Title"
# delegate to Post
presenter.content # "My Content"

Helpers

You can use present and present_each method to wrap objects. It will find presenter class in the prefix. (eg. Post => PostPresenter)

present(@post) do |post|
  # do something...
end

present_each(@posts) do |post|
  # do something...
end

You can specify presenter, too.

present(@post, CustomPresenter) do |post|
  # do something...
end

present_each(@posts, CustomPresenter) do |post|
  # do something...
end

You can use presenters to convert object array to presenters array

presenters(@posts).each_with_index do |post, index|
  # do something...
end

You can use the helper in the view in rails application.

Use Presenters in Presenter

If you want to use other presenters in the presenter. You can use following methods:

class UserPresenter < Presenter
  def name
    super || "Anonymous"
  end
end

class PostPresenter < Presenter
  def poster
    # You want to use UserPresenter and get its name here.
  end
end

# method 1
present(user).name

# method 2
UserPresenter.new(user).name

# method 3, if user is a ActiveRecord::Base
user.presenter.name

License

The gem is available as open source under the terms of the MIT License.

Contact

The project's website is located at https://github.com/emn178/presenters
Author: emn178@gmail.com