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#5479 ✓committed
javierm

Inconsistent behavior using "order" in scopes

Reported by javierm | August 27th, 2010 @ 07:44 PM | in 3.0.2

Using Rails 3.0RC2 (it happened in RC1 as well) with a SQLite3 database I've noticed the following behavior under both Ruby 1.8.7 and Ruby 1.9.2.

I've got a post class with the following scopes:

    scope :by_id, order("id")
    scope :by_title, order("title")

I see the following queries are generated by combining those scopes and the "order" method:

    Post.by_title.by_id
    SELECT "posts".* FROM "posts" ORDER BY id

    Post.order("title").order("id")
    SELECT "posts".* FROM "posts" ORDER BY title, id

    Post.order("title").by_id
    SELECT "posts".* FROM "posts" ORDER BY id

    Post.by_title.order("id")
    SELECT "posts".* FROM "posts" ORDER BY title, id

I don't think this is what most people would expect. I'd expect that using "by_id" and "order('id')" would be equivalent, but is not. Looks like the declared scope overrides the order but the "order" method chains the columns.

I'll try to investigate a bit further and provide a test case, but don't expect anything soon.

P.S: sorry if it's a duplicated bug. I've seen similar bugs about default scope and order, but thought were not the same.

Comments and changes to this ticket

  • javierm

    javierm August 27th, 2010 @ 11:05 PM

    Sooner than I expected, here's the failing test.

  • Neeraj Singh

    Neeraj Singh August 27th, 2010 @ 11:48 PM

    • Milestone set to 3.x
    • State changed from “new” to “open”
    • Assigned user set to “Neeraj Singh”
    • Tag set to rails 3
    • Importance changed from “” to “Low”
  • Neeraj Singh

    Neeraj Singh August 28th, 2010 @ 04:49 AM

    I have a fix for this one. However my fix is breaking a number of tests. Here I am discussing one of the tests that is failing because of my fix.

    Let's start from the beginning. We have a model which looks like this.

    class DeveloperOrderedBySalary < ActiveRecord::Base
      self.table_name = 'developers'
      default_scope :order => 'salary DESC'
      scope :by_name, :order => 'name DESC'
      scope :reordered_by_name, reorder('name DESC')
    
      def self.all_ordered_by_name
        with_scope(:find => { :order => 'name DESC' }) do
          find(:all)
        end
      end
    end
    

    Now the question is what kind of sql should be generated for the following case

    DeveloperOrderedBySalary.all_ordered_by_name
    

    The existing rails edge code would produce following sql

    SELECT "developers".* FROM "developers" ORDER BY name DESC
    

    I also happen to think that above sql is wrong. It is wrong because it does not take into account the default_scope. default_scope is always applied as the very first thing. And if the default_scope dictates order then that order should be followed. Notice that with_scope obeys default_scope in general, but in this case with_cope is NOT obeying default_scope.

    After my fix the sql generated is

    SELECT "developers".* FROM "developers" ORDER BY salary DESC, name DESC
    

    As I said earlier my fix for this issue is breaking a lot of tests similar to the case illustrated. I would like to have an opinion from a core team member on this topic.

  • Neeraj Singh

    Neeraj Singh August 28th, 2010 @ 10:12 PM

    Current behavior in rails 2-3-stable is

    class User < ActiveRecord::Base
      default_scope  :order => 'created_at desc'
    
      named_scope :custom, :order => 'name desc'
    end
    
    > User.all
    SELECT * FROM "users" ORDER BY created_at desc
    
    > User.custom
    SELECT * FROM "users" ORDER BY name desc
    
  • Santiago Pastorino

    Santiago Pastorino August 29th, 2010 @ 01:15 AM

    • Milestone cleared.
    • Assigned user changed from “Neeraj Singh” to “Santiago Pastorino”

    Neeraj only to write a bit of the progress we did on this. We have a patch and Neeraj is writing some tests.

  • Jeremy Kemper
  • Santiago Pastorino
  • Jeremy Kemper

    Jeremy Kemper October 15th, 2010 @ 11:02 PM

    • Milestone set to 3.0.2

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