From af5e1b4cc6fd3ae5f5e175751373a5e60934385b Mon Sep 17 00:00:00 2001
From: Pratik Naik <pratiknaik@gmail.com>
Date: Sun, 3 Jan 2010 19:42:29 +0530
Subject: Add Relation#except

---
 activerecord/CHANGELOG                             |  5 +++++
 .../lib/active_record/relation/spawn_methods.rb    | 22 ++++++++++++++++++++++
 activerecord/test/cases/relations_test.rb          | 12 ++++++++++++
 3 files changed, 39 insertions(+)

(limited to 'activerecord')

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 4846774deb..0cfd8cdc87 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,10 @@
 *Edge*
 
+* Add Relation#except. [Pratik Naik]
+
+  one_red_item = Item.where(:colour => 'red').limit(1)
+  all_items = one_red_item.except(:where, :limit)
+
 * Add Relation#delete_all. [Pratik Naik]
 
   Item.where(:colour => 'red').delete_all
diff --git a/activerecord/lib/active_record/relation/spawn_methods.rb b/activerecord/lib/active_record/relation/spawn_methods.rb
index 7b15279253..b9e3457aac 100644
--- a/activerecord/lib/active_record/relation/spawn_methods.rb
+++ b/activerecord/lib/active_record/relation/spawn_methods.rb
@@ -45,5 +45,27 @@ module ActiveRecord
 
     alias :& :merge
 
+    def except(*skips)
+      result = Relation.new(@klass, table)
+      result.table = table
+
+      [:eager_load, :preload, :includes].each do |load_method|
+        result = result.send(load_method, send(:"#{load_method}_associations"))
+      end
+
+      result.readonly = self.readonly unless skips.include?(:readonly)
+
+      result = result.joins(@relation.joins(@relation)) unless skips.include?(:joins)
+      result = result.group(@relation.groupings) unless skips.include?(:group)
+      result = result.limit(@relation.taken) unless skips.include?(:limit)
+      result = result.offset(@relation.skipped) unless skips.include?(:offset)
+      result = result.select(@relation.send(:select_clauses)) unless skips.include?(:select)
+      result = result.from(@relation.sources) unless skips.include?(:from)
+      result = result.order(order_clause) unless skips.include?(:order)
+      result = result.where(*@relation.wheres) unless skips.include?(:where)
+
+      result
+    end
+
   end
 end
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 7046420ebd..bcecf74737 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -539,4 +539,16 @@ class RelationTest < ActiveRecord::TestCase
     assert ! hen.new_record?
     assert_equal 'hen', hen.name
   end
+
+  def test_except
+    relation = Post.where(:author_id => 1).order('id ASC').limit(1)
+    assert_equal [posts(:welcome)], relation.all
+
+    author_posts = relation.except(:order, :limit)
+    assert_equal Post.where(:author_id => 1).all, author_posts.all
+
+    all_posts = relation.except(:where, :order, :limit)
+    assert_equal Post.all, all_posts.all
+  end
+
 end
-- 
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