BasicPresenter adds a layer of presentation logic to your application.
Its inspired from https://github.com/railscasts/287-presenters-from-scratch/ and http://svs.io/day/2012/12/27
Rails being a flexible framework starts with all methods being part of model and when it gets big, developers are haunted with the daunting task of its maintenance.
Leveraging Presentation pattern with Presenters requires lot of context loading with separating view/derived methods from actual objects and moving them to presenters and making relevant changes to instantiate right object wherever needed.
By letting the knowledge of Presenters slip through model leveraging delegation helps us with the movement of view/derived methods from actual objects to presenters without letting other code to know about the delegation and change. Strict movement and no other code change.
Presenters deal with presentation, so your models can concentrate on domain logic. Instead of polluting models with presenter logic, you can implement the presenter method in a presenter instead.
Requires active_support
Add this line to your application's Gemfile:
gem 'basic_presenter'
And then execute:
$ bundle
Or install it yourself as:
$ gem install basic_presenter
Or to use the edge version, add this to your Gemfile:
gem 'basic_presenter', :github => 'vinsol/basic_presenter'
rails g basic_presenter:installTo generate a presenter by itself:
rails g basic_presenter:presenter UserPresenters are stored in app/presenters, they inherit from
BasicPresenter::BasePresenter and are named based on the model they
present. We also recommend you create an ApplicationPresenter.
You can access the model using the domain_object method, or the model name (in this case user). For example:
# app/models/user.rb
class User
attr_accessor :first_name, :last_name
def initialize(first_name, last_name)
@first_name = first_name
@last_name = last_name
end
end
# app/presenters/application_presenter.rb
class ApplicationPresenter < BasicPresenter::BasePresenter
end
# app/presenters/user_presenter.rb
class UserPresenter < ApplicationPresenter
# You can access the model using the `domain_object` method,
# or the model name (in this case `user`). For example:
presents :user
@delegation_methods = [:first_name, :last_name]
# Use ActiveSupport `delegate`
delegate *@delegation_methods, to: :user
def full_name
first_name + last_name
end
endThe model name is either inferred from the model class name - taking
User and adding Presenter to it.
presents creates a wrapper for domain model object to call it close to
domain than something like domain_object
user = User.new('Vinsol', 'User')
user_presenter = UserPresenter.new(user)
user_presenter.full_name # Output: VinsolUser# app/models/user.rb
class User
include BasicPresenter::Concern
attr_accessor :first_name, :last_name
def initialize(first_name, last_name)
@first_name = first_name
@last_name = last_name
end
end
user = User.new('Vinsol', 'User')
user.presenter.full_name # Output: VinsolUser# app/presenters/admin_presenter.rb
class AdminPresenter < ApplicationPresenter
# You can access the model using the `domain_object` method,
# or the model name (in this case `admin`). For example:
presents :admin
@delegation_methods = [:first_name, :last_name]
# Use ActiveSupport `delegate`
delegate *@delegation_methods, to: :admin
def full_name
"#{first_name}-#{last_name}"
end
end
user = User.new('Vinsol', 'User')
user.presenter.full_name # Output: VinsolUser
user.presenter_class = AdminPresenter
user.presenter.full_name # Output: Vinsol-User# app/models/user.rb
class User
include BasicPresenter::Concern
attr_accessor :first_name, :last_name
@delegation_methods = [:full_name]
# Use ActiveSupport `delegate`
# No change in this line needed
# As BasicPresenter::Concern Module always exposes presenter method
# to return presenter instance
delegate *@delegation_methods, to: :presenter
def initialize(first_name, last_name)
@first_name = first_name
@last_name = last_name
end
end
user = User.new('Vinsol', 'User')
user.presenter.full_name # Output: VinsolUser
user.full_name # Output: VinsolUser
user.presenter_class = AdminPresenter
user.presenter.full_name # Output: Vinsol-User
user.full_name # Output: Vinsol-UserPENDING: The specs are placed in spec/presenters. Add type: :presenter if they are placed elsewhere.
Mozilla Public License Version 2.0
Free to use in open source or proprietary applications, with the caveat that any source code changes or additions to files covered under MPL V2 can only be distributed under the MPL V2 or secondary license as described in the full text.
- Fork it
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request
Copyright (c) 2014 vinsol.com, released under the New MIT License
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