How to extract common named_scopes from ActiveRecord models

Question

I have named_scope which is reused in multiple ActiveRecord models. For example:

  named_scope :limit, lambda {|limit| {:limit => limit}}

What is the best practice to extract this code to be shared across models. Is it possible to extract it to a module or should I rather reopen ActiveRecord::Base class?

score 21 · Answer 1 · answered Oct 09 '08 at 12:47

21

Use a module. Something like this should work:

module CommonScopes
  def self.included(base)
    base.class_eval do
      named_scope :limit, lambda {|limit| {:limit => limit}}
    end
  end
end

Then just include CommonScopes and you'll be good to go.

answered Oct 09 '08 at 12:47

Ben Scofield

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This seems to work for the class-level, but not the instance-level. For example: `User.limit(1)` works, but the second call to limit here raises an error: `users=User.limit(5); users.limit(1)`. Any solution for the instance level? – Matt Huggins Apr 18 '11 at 17:14

score 0 · Answer 2 · edited May 23 '17 at 12:08

0

@Matt via instance_eval, @see Shared scopes via module?

edited May 23 '17 at 12:08

Community

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answered Oct 17 '12 at 10:32

Hugo Stieglitz

55
3

How to extract common named_scopes from ActiveRecord models

2 Answers2