short_circuit
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