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Virtual attributes plugin lets you do two things: 1) define "virtual" attributes that work as usual AR attributes, but that are not saveable to the database 2) define preloadable attributes and associations that take field values from database queries and prepopulate virtual attributes or associations without the need of extra database query. For example, you have two associated tables Foo and Bar: class Bar < ActiveRecord::Base end class Foo < ActiveRecord::Base belongs_to :bar preloadable_association :bar preloadable_attribute :zee end b = Bar.create :name => 'Bar' f = Foo.create :name => 'Foo', :bar_id => b.id With preloadable_attribute you can use any value from the SQL query as attribute (just like with AR attribute). With preloadable association you can preload associated model from SQL query results without extra database query. The only thing you must do is to select all fields from associated model in the query, prefixed with "preloaded_<association_name>_". Example: f = Foo.find_by_sql("select *, '1' as zee from foos left outer join (select id as preloaded_bar_id, name as preloaded_bar_name from bars) as bars on foos.bar_id = bars.preloaded_bar_id").first assert_equal "Bar", f.bar.name assert_equal "1", f.zee Copyright (c) 2008-2009 Pluron, Inc. Released under the MIT license.