On-the-fly created named-scope raises 'undefined method `call' when called from subclass with cache_classes = true

Is anyone experiencing this same problem?

Same problem here. Rails 2.3.5. Using STI.

I am not able to reproduce this problem with rails3 edge.

ActiveRecord::Schema.define(:version => 20100624220122) do

  create_table "users", :force => true do |t|
    t.string   "name"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

end
class User < ActiveRecord::Base
  def self.create_second_order_scope
    return if respond_to?(:second_order)
    named_scope :second_order, :conditions => {}
  end

  def self.lab
    User.create_second_order_scope
    puts User.second_order.all.inspect
  end
end

class Admin::User < User
  def self.lab
    Admin::User.create_second_order_scope
    puts Admin::User.second_order.all.inspect
  end
end

# User.lab #=> produces sql query
# Admin::User.lab #=> produces sql query

Neeraj did you do config.cache_classes = true? What about 2-3-stable?

@Santiago I just did User.lab and Admin::User.lab in production environment and I get the same result.

will try with 2-3 and will let you know.

@Neeraj: at least in Rails 2.3.x, the issue is caused by the scope's method being propagated up the inheritance chain, while the scope conditions are not. The trick is that the scopes are stored in an inheritable attribute - not a big deal for 3.0, since the methods are defined in-place without an actual reference to the array (see around line 89 in named_scopes.rb on master). On 2.3.x, the method that's defined only references the array:

define_method name do |*args|
  scopes[name].call(self, *args)
end

Thus, in Admin::User above, you end up with a second_order method inherited from the parent, but scopes[:second_order] returns nil since the subclass has an empty hash which was inherited from the parent at definition time.

I can confirm that it is indeed and error with 2-3-stable. But it works fine on rails3 edge.

I put together some code based on the Hobo link placed here. I am still testing it, but it seems to work so far. Once I am sure that it works, I will put together the patch.

Here is the change to lib/active_record/named_scope.rb against 2.3.10

def named_scope(name, options = {}, &block)

    name = name.to_sym

    scopes[name] = lambda do |parent_scope, *args|
      Scope.new(parent_scope, case options
        when Hash
          options
        when Proc
          if self.model_name != parent_scope.model_name
            options.bind(parent_scope).call(*args)
          else
            options.call(*args)
          end
      end, &block)
    end

    singleton_class.send :define_method, name do |*args|
      scopes[name].call(self, *args)
    end

    _name = name.to_sym
    _scope = scopes[_name]
    subclasses.each do |s|
      s.scopes[_name] = _scope
    end

  end
end

This issue has been automatically marked as stale because it has not been commented on for at least three months.

The resources of the Rails core team are limited, and so we are asking for your help. If you can still reproduce this error on the 3-0-stable branch or on master, please reply with all of the information you have about it and add "[state:open]" to your comment. This will reopen the ticket for review. Likewise, if you feel that this is a very important feature for Rails to include, please reply with your explanation so we can consider it.

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I just ran into this today on Rails 2.3.10 uses searchlogic.

I've attached a patch with a test that exposes the bug on Rails 2.3 stable and a fix for the issue. The fix is basically mrcsparker's fix above.

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