```ruby
class SessionsController < ApplicationController
  def new
  end

  def create
  end

  def destroy
  end
end
```

Implement login in and out by storing the user_id in the session.
user
```ruby
class SessionsController < ApplicationController
  def new
  end

  def create
    user = User.find_by(name: params[:name])
    if user and user.authenticate(params[:password])
      session[:user_id] = user.user_id
      redirect_to admin_url
    else
      redirect_to login_url, alert 'Invalid user/password combination'
    end
  end

  def destroy
    session[:user_id] = nil
    redirect_to store_url, notice: 'Logged out'
  end
end
```
assistant