rails friendly_id and check if entry exists

Question

How to check if friendly_id entry exists before get it?

For example:

  def book
   @book = Book.find(params[:book_id])
  end

It's ok, but i want check before if friendly_id exists, something like:

def book
  if Book.exists?(params[:book_id])
    @book = Book.find(params[:book_id])
  else
    #404 not found
  end

Answer 1

Rescue from RecordNotFound exception ==>

def book
  @book = Book.find(params[:book_id])
  #OK
rescue ActiveRecord::RecordNotFound => e
  head :not_found
end