Ruby on Rails Interactor

Before interactor we use to write complex business logic in some class in the ActiveRecord /models directory and that class can have too many responsibilities so while testing we could stuck between tediously slow test-suites as these objects are often fetched from the database.

The solution is a concept called “Interactors”. Rails interactor is like an object that has a single purpose and each interactor represent one thing that your application does. It encapsulates complex business logic and make your ActiveRecord classes skinny.
By looking at the names of your Interactors, you should be able to tell what your application does for example SignUp,

To start with add Interactor to your Gemfile and bundle install.

gem "interactor-rails", "~> 2.0"

It is compatible with Ruby 1.9.3, 2.0, 2.1, 2.2, or 2.3 on Rails 3, 4, or 5.

It ensures that app/interactors is included in your autoload paths.

After including the interacter gem, make sure you have   "app/interactors " in your application path.

Lets create an interactor "AuthenticateUser", this interactor will authenticate a user for you

class AuthenticateUser
  include Interactor

  def call
    if user = User.authenticate(context.email, context.password)
      context.user = user
      context.token = user.secret_token
    else
      context.fail!(message: "authenticate_user.failure")
    end
  end
end

Here "context" contains everything that an Interactor needs to work with. The params from the controller sets the context when an Interactor is called.

Now call this interactor AuthenticateUser in the Controller

class SessionsController < ApplicationController
  def create
    result = AuthenticateUser.call(session_params)

    if result.success?
      session[:user_token] = result.token
      redirect_to root_path
    else
      flash.now[:message] = t(result.message)
      render :new
    end
  end

  private

  def session_params
    params.require(:session).permit(:email, :password)
  end
end

Interactor has a couple of convenient methods like success? and failure? that controller can use as above.
So Interactors are a nice way to reuse operations and specifying a sequence of actions in order to execute business logic.