Is there a way to make a before_save conditional?

Rails 5

I've had success defining a private method which contains the boolean logic and then passing it as a symbol (that last part seems like a requirement):

before_save do_something, if: :private_boolean_method?

I also recently found out you can simply pass a block (took me a while to figure out the syntax):

before_save do_something, if: -> { condition == "met" }

you can use :if

before_save do_something, :if => Proc.new {|model| model.some_boolean_attr_or_method }

or simply

before_save do_something, :if => some_condition

EDIT:

for a quick reference, there's an excellent guide about this:

http://guides.rubyonrails.org/active_record_callbacks.html#conditional-callbacks