short_circuit

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Short Circuit adds simple presenters for Rails views.

Usage

Install the gem in your Gemfile:

ruby gem 'short_circuit'

Include short_circuit in your model:

```ruby # app/models/user.rb

class User < ActiveRecord::Base include ShortCircuit::Presentable

attr_accessible :first_name, :last_name, :job_title, :member_since end ```

Create a presenter:

```ruby # app/presenters/user_presenter.rb

class UserPresenter < ShortCircuit::Presenter def first_name @user.first_name.titleize end

def full_name “#first_name #last_name” end

def job_title @user.job_title || ‘not listed’ end

def member_since @user.member_since.to_formatted_s(:long) end

def error_response(method, *args, &block) link_to ‘N/A’, root_path end end ```

No additional controller code is necessary. Retrieve the model as you normally would:

```ruby # app/controllers/users_controller.rb

class UsersController < ApplicationController def show @user = User.find(params[‘id’]) end end ```

In the view, you don’t need to instantiate any presenter/decorator objects, just use the model:

```ruby # Normal method vs presenter method: @user.first_name # john @user.present :first_name # John

Missing presenter method is delegated to model:

@user.last_name # smith @user.present :last_name # smith

Method defined on presenter object:

@user.full_name # NoMethodError @user.present :full_name # John smith

Formatted data returned by presenter method:

@user.member_since # 2013-02-28 20:46:32 UTC @user.present :member_since # February 28, 2013 20:46

Presenter method prevents nil error by returning default data:

@user.job_title.upcase # undefined method ‘upcase’ for nil:NilClass @user.present(:job_title).upcase # NOT LISTED

Presenter method silences nil error and returns alternative content:

@user.not_a_real_method # NoMethodError @user.present :not_a_real_method # N/A

Present! method does not silence errors:

@user.present! :not_a_real_method # NoMethodError ```

Design goals

  • Minimize project size and scope
  • Preserve direct access to model attributes
  • Create a separate access point for presenter methods
  • Silence accessor errors by default
  • Delegate missing presenter methods to the model object