Controllers

Roles of a controller

A Controller can end up with a lot of responsibilities. The first goal of a controller is to render a view to a client based on a request. A lot of logic can happen in the process but think to controller like a "glue" to make the application core logic accessible from the outside.

Location

• app/controllers/
• Should be suffix with _controller.rb

Dos

• Use before_action with only and except if necessary
• Use strong_params for model mutations (POST, UPDATE)
• Use private methods if needed but the goal is to limit the logic in controllers. private method should only be used to render errors or generic redirects
• Use Domain
• Use Services
• Use Presenters
• Use Decorators
• Validate the params
• Try to keep the standard action names for CRUD: (index,show,edit,new,update,create,delete)
• Do authentication
• Do authorizations (ACL)
• Manipulate the sessions for each visitor
• Manipulate the flash notices
• Do redirect
• Do render
• Can call Mailers
• Can call Background Jobs
• Try to keep coherent param names in different views, to limit the params-handling code

Don'ts

• Do complexe ActiveRecord queries (use Query Objects instead)
• Create complexe if/else workflow in one action (use Services instead)
• Have too much private methods (use Domain business logic or other classes instead)
• Call external API services (HTTP requests or what ever)
• Fetch data from multiple models: Try to limit the number and kind of models you call in an action. Create another class if you need to manipulate multiple models
• Know too much about your app, the database and caching stuff: The configuration for databases, caching and others things are done in config/.

Code

class ExampleController < ApplicationController
  before_action :authenticate_user

  def dashboard
    @data = UserDashboard.new(params).call
  end

  def register
    new_user = UserRegistration.new(params).call
    redirect_to dashboard_path
  end

  def create
    event = Event.new(event_params)

    if event.save
      redirect_to event_path(event)
    else
      render "new"
    end
  end

  private

  def event_params
    params.require(:event).permit(:name, :start_at, :end_at)
  end
end