访问Rails类/模型方法

Question

I am new to rails and am figuring out the best ways to write certain methods.

I am trying to write a method that belongs to a certain model and can be accessed without initiating an instance. So far I have this under my class PaymentNotification < ActiveRecord::Base

def url
   url_for(:controller => 'payment_notifications', :only_path => false)
end

The problem here is that I need to do this to access the url

n = PaymentNotification.new
n.url

In my code, I want to be able to write PaymentNotification.url to access the method relevant to that model.

Maybe I am thinking about this the wrong way and someone can guide me. Basically, what I am trying to achieve is that each model can have its set of methods and attributes so that they all are organized and I know from the code which file each method is declared in, instead of just calling a

payment_notification_url

which may be located in any of the irrelevant initialization files. I saw helper methods but it seems like i still won't be able to use a dot syntax and will have to write something like "payment_notification_url" to access my url

Any ideas on the best way to go about doing this?

Answer 1

You need to define a class method via the self keyword.

def self.url
   url_for(:controller => 'payment_notifications', :only_path => false)
end

Then you can use PaymentNotification.url

class A
  def self.a
    p "Class method"
  end

  def b
    p "Instance Method"
  end
end

A.a   #Class method
#A.b #NoMethodError

a = A.new
a.b #Instance Method
#a.a    #NoMethodError