From d3006f3503cd62510f669fcac84f8dc47c3b333c Mon Sep 17 00:00:00 2001
From: Yves Senn <yves.senn@gmail.com>
Date: Sun, 11 Nov 2012 17:15:26 +0100
Subject: backport #8176, `#pluck` can be used on a relation with `select`
 clause.

Conflicts:

	activerecord/CHANGELOG.md
	activerecord/lib/active_record/relation/calculations.rb
	activerecord/test/cases/calculations_test.rb
---
 activerecord/CHANGELOG.md                               | 9 +++++++++
 activerecord/lib/active_record/relation/calculations.rb | 4 +++-
 activerecord/test/cases/calculations_test.rb            | 6 ++++++
 3 files changed, 18 insertions(+), 1 deletion(-)

(limited to 'activerecord')

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index d8493205d7..71a740f300 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,5 +1,14 @@
 ## Rails 3.2.10 (unreleased)
 
+*  `#pluck` can be used on a relation with `select` clause. [Backport #8176]
+   Fix #7551
+
+   Example:
+
+        Topic.select([:approved, :id]).order(:id).pluck(:id)
+
+   *Yves Senn*
+
 *   Do not create useless database transaction when building `has_one` association. [Backport #8154]
 
     Example:
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index 802059db21..8b605dd4f1 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -178,7 +178,9 @@ module ActiveRecord
     #
     def pluck(column_name)
       column_name = column_name.to_s
-      klass.connection.select_all(select(column_name).arel).map! do |attributes|
+      relation = clone
+      relation.select_values = [column_name]
+      klass.connection.select_all(relation.arel).map! do |attributes|
         klass.type_cast_attribute(attributes.keys.first, klass.initialize_attributes(attributes))
       end
     end
diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index cf1181e829..63383bded9 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -487,4 +487,10 @@ class CalculationsTest < ActiveRecord::TestCase
   def test_pluck_with_qualified_column_name
     assert_equal [1,2,3,4], Topic.order(:id).pluck("topics.id")
   end
+
+  def test_pluck_replaces_select_clause
+    taks_relation = Topic.select([:approved, :id]).order(:id)
+    assert_equal [1,2,3,4], taks_relation.pluck(:id)
+    assert_equal [false, true, true, true], taks_relation.pluck(:approved)
+  end
 end
-- 
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