Explained difference between scope & class method

[ghost]

Summary

Today in the Ruby on Rails slack, the question arose what the difference between a scope and a class method is.

After googling I found an accepted stack overflow answer which I partly copied in order to answer the question.

This part copy of mine included the wrong quote from this guide, that a scope and a class method is exactly the same. This is simply not true.

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[ghost]

Example for false information being spread based on this guide: https://stackoverflow.com/questions/32930312/ruby-on-rails-activerecord-scopes-vs-class-methods

[schneems]

Thanks!

[kamipo]

exactly the same is not true, but the remaining part is almost the same with here:

rails/guides/source/active_record_querying.md

Lines 1360 to 1370 in 97feb49

	Like the other examples, this will behave similarly to a class method.
	```ruby
	class Article < ApplicationRecord
	def self.created_before(time)
	where("created_at < ?", time) if time.present?
	end
	end
	```
	However, there is one important caveat: A scope will always return an `ActiveRecord::Relation` object, even if the conditional evaluates to `false`, whereas a class method, will return `nil`. This can cause `NoMethodError` when chaining class methods with conditionals, if any of the conditionals return `false`.

[bogdanvlviv]

How about removing this part in favor of the info below in order to not repeat yourself?

[kamipo]

Yeah, it is a good idea to me.