When you inherit from an action class, you also inherit much of its behavior. This includes:
- Dependencies specified with the Deps mixin
- Parameter validation schemas
You can use action inheritance to ensure that broad collections of actions all have consistent key behaviors.
For example, consider the following base action class.
# apps/action.rb module Bookshelf class Action < Hanami::Action include Deps["authenticator"] format :json before :authenticate_user! private def authenticate_user!(request, response) halt 401 unless authenticator.valid_api_token?(request.headers["X-API-Token"]) end end end
Any class that inherits from this will:
- Have the
authenticatorobject available to its instance methods
- Expect JSON requests and return JSON responses
- Ensure that requests are authenticated based on the
X-API-Tokenand return a 401 error if not
Courtesty of the inheritance, subclasses gain all this behavior without any additional code.
# app/actions/books/index.rb module Bookshelf module Actions module Books class Index < Bookshelf::Action end end end end
Standard base classes
When you create a new Hanami app, Hanami generates a standard base class for all your actions to inherit from.
# apps/action.rb module Bookshelf class Action < Hanami::Action end end
Hanami also generates a base action class for each slice.
# slices/admin/action.rb module Admin class Action < Hanami::Action end end
These base classes can be a useful place to put any config or behavior that you want for every action in your app or slice.
Leveraging action inheritance
Since actions are just regular Ruby classes, you can also use all the standard Ruby techniques to share behaviour across various subsets of your actions.
For example, you could make a new base class for a specific group of actions:
# app/actions/user_profile/base.rb module Bookshelf module Actions module UserProfile class Base < Bookshelf::Action before :authenticate_user! private def authenticate_user!(request, response) # halt 401 unless ... end end end end end
Any classes within this namespace could inherit from
Actions::UserProfile::Base and share common user authentication behaviour.
Alternatively, for authentication behaviour that may need to be used across a range of disparate actions, you could also consider a module.
# app/actions/authenticated_action.rb module Bookshelf module Actions module AuthenticatedAction def self.included(action_class) action_class.before :authenticate_user! end private def authenticate_user!(request, response) # halt 401 unless ... end end end end
With this, any action requiring authentication can include the module.
module Bookshelf module Actions module UserProfile class Update < Bookshelf::Action include AuthenticatedAction end end end end