action_param.md

ActionParameter

ActionParameter helps you move all your parameter's logic into it's own class. This way you'll keep your controllers dry and they would be easier to test.

Before

# app/controllers/users_controllers.rb
class UsersController < ActionController::Base
  def create
    User.create(user_params)
  end

  private
    def user_params
      params.require(:user).permit(:name, :age)
    end
end

After

# app/controllers/users_controllers.rb
class UsersController < ActionController::Base
  def create
    # It automatically deduces which Parameters class from Controller's name
    User.create(permitted_params.permit)
  end
end

# app/parameters/user_parameters.rb
class UserParameter < ActionParameter::Base
  def permit
    params.require(:user).permit(:name, :age)
  end
end

Install

ActionParameter works with Rails 3.0 onwards and Ruby 1.9.3 onwards. You can add it to your Gemfile with:

gem 'action_parameter'

Run the bundle command to install it.

Usage

####Generator

rails generate parameter [MODEL_NAME]

Will create app/parameters/[model_name]_parameters.rb.

####Controller Helpers

• permitted_params: Returns an ActionParameter instance.

permitted_params(options={})

#####Options Hash

• options - Hash with two valid keys :class and :locals.
• options[:class] - Symbol value with the name of the Parameters class you want to use.
• options[:locals] - Hash used to create helper methods available for the ActionParameter instance.

#####Example 1

# app/controllers/people_controllers.rb
class PeopleController < ActionController::Base
  def create
    Person.create(permitted_params.permit) # This will call to PersonParameters' permit method
  end
end

# app/parameters/person_parameters.rb
class PersonParameters < ActionParameter::Base
  def permit
    params.require(:person).permit(:name, :age)
  end
end

#####Example 2

# app/controllers/people_controllers.rb
class PeopleController < ActionController::Base
  def create
    Person.create(permitted_params(class: :user).sign_up) # This will call to UserParameters' sign_up method
  end
end

# app/parameters/user_parameters.rb
class UserParameters < ActionParameter::Base
  def sign_up
    params.require(:person).permit(:name, :age)
  end
end

####Parameter Helpers

#####Default Helpers

• params: Returns params from the current controller request which instantiated the Parameter class.
• controller_name: Returns the controller's name from which the Parameter class was instantiated.
• action_name: Returns the action's name from the controller from which the Parameter class was instantiated.

#####Creating New Helpers

If you want to create new helper methods for you parameters class, just pass a hash using :locals. Let say you want to make @current_user available for the UserParameter's class, then you'll need to use the :locals option to tell the UserParameters class to create a new helper that returns @current_user.

permitted_params(class: :user, locals: { current_user:   @current_user,
                                         another_helper: @value })

This will create current_user and another_helper methods and they will be available in UserParameters class.

#####Example

# app/controllers/users_controllers.rb
class UsersController < ActionController::Base
  def create
    Person.create(permitted_params(locals: { current_user: @current_user }).sign_up)
    # This will call to UserParameters' sign_up method and will also create a
    # helper method named 'current_user' which will return @current_user
  end
end

# app/parameters/user_parameters.rb
class UserParameters < ActionParameter::Base
  def sign_up
    if current_user # Method created using :locals option
      params.permit!
    else
      params.require(:person).permit(:name, :age)
    end
  end
end