From 565afd93e7fd970d9a69fc33096fbf45de457695 Mon Sep 17 00:00:00 2001
From: Manfred Stienstra <manfred@fngtps.com>
Date: Tue, 10 Mar 2009 15:32:36 +0100
Subject: [PATCH] Filter the count column on :select options coming from associations to make them work on MySQL 5.1 and Sqlite3.

---
 activerecord/lib/active_record/calculations.rb     |   10 +++++++---
 .../has_many_through_associations_test.rb          |    4 ++++
 activerecord/test/models/tag.rb                    |    2 ++
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/activerecord/lib/active_record/calculations.rb b/activerecord/lib/active_record/calculations.rb
index f077818..c10d88f 100644
--- a/activerecord/lib/active_record/calculations.rb
+++ b/activerecord/lib/active_record/calculations.rb
@@ -150,10 +150,10 @@ module ActiveRecord
           #   selects specified by scopes
           case args.size
           when 0
-            column_name = scope(:find)[:select] if scope(:find)
+            column_name = sanitize_column_for_count_options(scope(:find)[:select]) if scope(:find)
           when 1
             if args[0].is_a?(Hash)
-              column_name = scope(:find)[:select] if scope(:find)
+              column_name = sanitize_column_for_count_options(scope(:find)[:select]) if scope(:find)
               options = args[0]
             else
               column_name = args[0]
@@ -163,9 +163,13 @@ module ActiveRecord
           else
             raise ArgumentError, "Unexpected parameters passed to count(): #{args.inspect}"
           end
-
+          
           [column_name || :all, options]
         end
+        
+        def sanitize_column_for_count_options(column)
+          (column =~ /^[`"]\w+[`"]\.\*$/) ? '*' : :all
+        end
 
         def construct_calculation_sql(operation, column_name, options) #:nodoc:
           operation = operation.to_s.downcase
diff --git a/activerecord/test/cases/associations/has_many_through_associations_test.rb b/activerecord/test/cases/associations/has_many_through_associations_test.rb
index c3ad0ee..aa40a1d 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -258,4 +258,8 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
   def test_has_many_association_through_a_has_many_association_with_nonstandard_primary_keys
     assert_equal 1, owners(:blackbeard).toys.count
   end
+
+  def test_count_through_has_many
+    assert_equal 1, posts(:welcome).tags.general.count
+  end
 end
diff --git a/activerecord/test/models/tag.rb b/activerecord/test/models/tag.rb
index a581b38..a3421f5 100644
--- a/activerecord/test/models/tag.rb
+++ b/activerecord/test/models/tag.rb
@@ -4,4 +4,6 @@ class Tag < ActiveRecord::Base
   has_one  :tagging
 
   has_many :tagged_posts, :through => :taggings, :source => :taggable, :source_type => 'Post'
+
+  named_scope :general, :conditions => { :name => 'General' }
 end
\ No newline at end of file
-- 
1.6.1.3