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#3373 ✓stale
Maxim Kulkin

Embed scoped collections inside :conditions option as SQL

Reported by Maxim Kulkin | October 13th, 2009 @ 07:13 PM

When scoped collections are used as a value for some attribute in :conditions clause, the generated SQL contains "attribute IN ( ... )" clause, where "( ... )" is enumeration of values of scoped collection. To do that an extra SQL clause is executed to get items of scoped collection. But in fact scoped collection can be inserted as a sub-SELECT.


@@@ ruby
    class PaymentType < AR::Base
      named_scope :credit_cards, :conditions => { :credit_card => true }

    Orders.all(:conditions => { :payment_type_id => PaymentType.credit_cards })

This could be translated into a single query:

@@@ sql
    SELECT * from `orders` WHERE payment_type_id IN (SELECT id FROM `payment_types` WHERE credit_card = 1)


Specially treat AR::NamedScope::Scope values in AR::Base#quote_bound_value

@@@ ruby
    def quote_bound_value(value) #:nodoc:
      if ActiveRecord::NamedScope::Scope === value
        scope = value.scope(:find) || {}
        field = (scope[:select] || value.primary_key).to_s.split(/,/).first.strip
        return value.construct_finder_sql(:select => field)


This patch allows
1. Select #primary_key attribute by default.
2. If :select option is present, use first attribute specified.

If for some reason scoped collection should be embedded as enumeration, one can e.g. instantiate it manually (by calling #all or #to_a).

Comments and changes to this ticket

  • Rohit Arondekar

    Rohit Arondekar October 6th, 2010 @ 06:40 AM

    • State changed from “new” to “stale”
    • Importance changed from “” to “”

    Marking ticket as stale. If this is still an issue please leave a comment with suggested changes, creating a patch with tests, rebasing an existing patch or just confirming the issue on a latest release or master/branches.

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