Variable call in Ruby on Rails tutorial listing 6.23

Question

The question is in regard to the Rails tutorial . In particular I have a doubt about listing 6.23 , this line:

before_save { |user| user.email = email.downcase }

I am curious about the variable "email" - where does it come from? Is it some kind of short Ruby syntax to call the left-hand side variable? Or does it call to the model's attribute (it would make passing the block variable redundant though)?

I'd appreciate anyone ridding me of my confusion.

Answer 1

Yes, you can omit passing the user to the block

before_save { self.email = email.downcase }

I personally prefer not using blocks and write named methods for this

before_save :reformat_email


private
def reformat_email
  self.email = email.downcase
end

Answer 2

This is only valid if user in the example is the same as self AND regarding the example with using before_save in an ActiveRecord::Base class

email is short for user.email , but when assigning a value you can't use email = , you must do user.email = otherwise you will only assign to a local variable.

The example is changing what's in user.email to user.email.downcase

And I think that when you use a before_save with an argument it will be self in that argument