Question

I’ve been studing Rails for a not such a long time up to now …. so if there are feel free to correct me

I see that there are two ways of defining methods in rails

1. def method_name(param)
2. def self.method_name(param)

The difference (as i understand) is that 1 is mainly used in controllers while 2 is used in models… but occasionaly i bump into methods in models that’re defined like 1.

Could you explain to me the main difference of thease two methods?

Answer 1

Number 1. This defines a instance method, that can be used in instances of the model.
Number 2. This defines a class method, and can only be used by the class itself.
Example:

class Lol
  def instance_method
  end
  def self.class_method
  end
end

l = Lol.new
l.instance_method #=> This will work
l.class_method #=> This will give you an error
Lol.class_method #=> This will work