Can you alias a scope in Rails?

Question

Say I have this scope:

scope :with_zipcode, lambda { |zip| where(zipcode: zip) }

and I want an equivalent scope

scope :has_zipcode, lambda { |zip| where(zipcode: zip) }

is there a way to alias one scope to another? For instance something like

alias :with_zipcode, :has_zipcode

P.S. I know this is a contrived and unrealistic example, just curious to know if it is possible!

Thanks!

Answer 1

Yes you can. Just remember that scopes are class methods so that you need to alias in the context of the class:

class User < ActiveRecord::Base
  scope :with_zipcode, lambda { |zip| where(zipcode: zip) }
  singleton_class.send(:alias_method, :has_zipcode, :with_zipcode)
end

Answer 2

Another solution is to call one scope from another

class User < ActiveRecord::Base
  scope :with_zipcode, lambda { |zip| where(zipcode: zip) }
  scope :has_zipcode,  lambda { |zip| with_zipcode(zip)   } # essentially an alias
end

Using singleton_class.send(:alias_method, :a, :b) is probably less ambiguous, but just wanted to alert to another option.

Answer 3

An alternative way to define an alias for a class method which I personally find a bit more self-explanatory:

class User < ActiveRecord::Base
  scope :with_zipcode, lambda { |zip| where(zipcode: zip) }

  class << self
    alias has_zipcode with_zipcode
  end
end