From 0da022b85086ab9c8789c4fb50a1e821045885c4 Mon Sep 17 00:00:00 2001
From: Wolfram Arnold <wolfram@wtaconsulting.net>
Date: Sun, 28 Dec 2008 23:29:57 +0100
Subject: [PATCH] #1652 fixed - pass all options except :order and :select to the .count method invoked for .size and .empty? if the data has not been loaded yet.

---
 activerecord/lib/active_record/named_scope.rb |   21 +++++++++++++++++++--
 activerecord/test/cases/named_scope_test.rb   |   22 ++++++++++++++++++++++
 activerecord/test/models/post.rb              |    9 +++++++++
 3 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/activerecord/lib/active_record/named_scope.rb b/activerecord/lib/active_record/named_scope.rb
index 83043c2..12701f3 100644
--- a/activerecord/lib/active_record/named_scope.rb
+++ b/activerecord/lib/active_record/named_scope.rb
@@ -69,6 +69,13 @@ module ActiveRecord
       #     end
       #   end
       #
+      # Note that most options available with the +find+ method apply here too.  Calling +size+ or +empty+ will resolve
+      # to a <tt>SELECT COUNT(*)...</tt> and ignore an explicit :select or :order option, if given.  The :group option and others will
+      # be processed, however.
+      #
+      # Note also that the +size+ and +length+ methods are not equivalent when the data has not yet been loaded.  In that
+      # case, +size+ will also invoke a <tt>SELECT COUNT(*)</tt> query while +length+ will run the full query.  If the data has been
+      # loaded, the behavior of the two methods is equivalent.  This behavior is analogous to ActiveRecord Association collections. 
       #
       # For testing complex named \scopes, you can examine the scoping options using the
       # <tt>proxy_options</tt> method on the proxy itself.
@@ -137,11 +144,21 @@ module ActiveRecord
       end
 
       def size
-        @found ? @found.length : count
+        if @found
+          @found.length
+        else
+          ct = count(@proxy_options.except(:select, :order))
+          ct.is_a?(Numeric) ? ct : ct.length
+        end
       end
 
       def empty?
-        @found ? @found.empty? : count.zero?
+        if @found
+          @found.empty?
+        else
+          ct = count(@proxy_options.except(:select, :order))
+          ct.is_a?(Numeric) ? ct.zero? : ct.empty?
+        end
       end
 
       def respond_to?(method, include_private = false)
diff --git a/activerecord/test/cases/named_scope_test.rb b/activerecord/test/cases/named_scope_test.rb
index 64e8997..776933d 100644
--- a/activerecord/test/cases/named_scope_test.rb
+++ b/activerecord/test/cases/named_scope_test.rb
@@ -272,6 +272,28 @@ class NamedScopeTest < ActiveRecord::TestCase
     end
   end
 
+  def test_custom_select_works
+    expected_posts = posts(:sti_comments, :welcome, :sti_post_and_comments)
+    assert_queries(1) do
+      assert_sql(/SELECT posts\.\*, COUNT\(\*\) AS comment_count/i) do
+        most_commented_posts = Post.most_commented(3,0)
+        assert_equal expected_posts, most_commented_posts
+      end
+    end
+  end
+
+  def test_empty_should_use_count_and_honor_group_option
+    assert_queries(1) do
+      assert_sql(/SELECT COUNT\(\*\) AS count_all.*GROUP BY posts\.id/i) { assert !Post.most_commented(3,0).empty? }
+    end
+  end
+
+  def test_size_should_use_count_and_honor_group_option
+    assert_queries(1) do
+      assert_sql(/SELECT COUNT\(\*\) AS count_all.*GROUP BY posts\.id/i) { assert_equal 3, Post.most_commented(3,0).size }
+    end
+  end
+
   def test_chaining_with_duplicate_joins
     join = "INNER JOIN comments ON comments.post_id = posts.id"
     post = Post.find(1)
diff --git a/activerecord/test/models/post.rb b/activerecord/test/models/post.rb
index e0d8be6..21abacb 100644
--- a/activerecord/test/models/post.rb
+++ b/activerecord/test/models/post.rb
@@ -5,6 +5,15 @@ class Post < ActiveRecord::Base
       :joins => 'JOIN authors ON authors.id = posts.author_id'
     }
   }
+  
+  named_scope :most_commented,
+              Proc.new { |limit, offset| { :select => 'posts.*, COUNT(*) AS comment_count',
+                                           :joins => :comments, 
+                                           :limit => limit,
+                                           :group => 'posts.id',
+                                           :order => 'comment_count DESC, comments.id ASC',
+                                           :offset => offset
+                                         } }
 
   belongs_to :author do
     def greeting
-- 
1.5.6.3