I'm trying to call an instance method (defined in model) from the instance variable in controller but could not get that work and server logs saying
undefined method `active_users' for #< Admin
controller
@admin = Admin.first
@admin.active_users
Admin Model
def self.active_users
byebug
end
I know that we can call it through the class directly like Admin.active_users .
Why is it not accessible by instance of the class?
active_users method is defined for Admin object, not for its instances.
I do not know what you are trying to do, but message receiver matters.
To make @admin.active_users work, define a method an instance method:
def active_users
byebug
end
The thing is, that active_users (both with and without self) are instance methods. It is just that objects for which these methods defined are different.
The method with self is a "class instance method", while the one without self is an "instance method", e.g. method accessible by instances of the class Admin.
active_users is a method on completely separate instance, Admin of type Class, not @admin of type Admin.When you write def self.something_method, method will be available only for class, as in your example. If you want create method for object, you have to create method without self, like this: def something_method.
For example:
class Admin
def self.class_method
p 'class method'
end
def something_method
p 'method for object'
end
end
@admin = Admin.create(something_params)
# You can also use 'Admin.new', but it will not save your admin in database, or 'Admin.first', like in your example.
@admin.something_method
#=> 'method for object'
@admin.class_method
#=> not working :(
Admin.something_method
#=> not working :(
Admin.class_method
#=> 'class method'
