Question

I have a protected method in my application contoller

def current_user
  @current_user ||= User.find_by_id(session[:user_id])
end

I was wondering what ||= means?
I’ve been trying to search and find out, but to no avail.

Answer 1

Basically, a ||= b means assign b to a if a is null or undefined or false (i.e. false-ish value in ruby), it is similar to a = b unless a, except it will always evaluate to the final value of a (whereas a = b unless a would result in nil if a was true-ish).