CODEWITHSUNDEEP
ruby-on-railsruby
beck03076
beck03076

Reputation: 3308

How to alias a class method in rails model?

I want to alias a class method on one of my Rails models.

  def self.sub_agent
   id = SubAgentStatus.where(name: "active").first.id
   where(type: "SubAgent",sub_agent_status_id: id).order(:first_name)    
  end

If this was an instance method, I would simply use alias_method, but that doesn't work for class methods. How can I do this without duplicating the method?

Upvotes: 37

Views: 17453

Answers (6)

Mike Slinn
Mike Slinn

Reputation: 8403

You can use alias_method with any class, not just classes that you wrote, and this answer does not require Rails.

For example, to alias the method ActiveSupport::NumberHelper.number_to_human_size as to_human:

require 'active_support'
require 'active_support/core_ext/numeric/conversions'

ActiveSupport::NumberHelper.alias_method :to_human, :number_to_human_size

nh = ActiveSupport::NumberHelper
puts nh.to_human 123456

The above prints: 121 KB.

Upvotes: 0

Neeraj Kumar
Neeraj Kumar

Reputation: 7511

class Foo

  def self.sub_agent
    id = SubAgentStatus.where(name: "active").first.id
    where(type: "SubAgent",sub_agent_status_id: id).order(:first_name) 
  end

  self.singleton_class.send(:alias_method, :sub_agent_new, :sub_agent)

end

Upvotes: 1

seigel
seigel

Reputation: 206

A quick reminder that would have gotten me to the right behaviour a bit faster is that this alias_method'ing should happen as the last thing of your class definition.

class Foo
  def self.bar(parameter)
    ....
  end

  ...

  singleton_class.send(:alias_method, :new_bar_name, :bar)
end

Good luck! Cheers

Upvotes: 1

nikolayp
nikolayp

Reputation: 17919

To add instance method as an alias for class method you can use delegate :method_name, to: :class

Example:

class World
  def self.hello
    'Hello World'
  end

  delegate :hello, to: :class
end

World.hello
# => 'Hello World'
World.new.hello
# => 'Hello World'

Link on documentation

Upvotes: 2

fuzzygroup
fuzzygroup

Reputation: 1149

I can confirm that:

class <<self
  alias_method :alias_for_class_method, :class_method
end

works perfectly even when it is inherited from a base class. Thanks!

Upvotes: 1

mohamed-ibrahim
mohamed-ibrahim

Reputation: 11137

You can use:

class Foo  
   def instance_method       
   end  

   alias_method :alias_for_instance_method, :instance_method

   def self.class_method
   end  

   class <<self  
     alias_method :alias_for_class_method, :class_method
   end  
 end

OR Try:

self.singleton_class.send(:alias_method, :new_name, :original_name)

Upvotes: 60

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