1 files changed, 22 insertions, 11 deletions

diff --git a/activerecord/lib/active_record/associations/association_scope.rb b/activerecord/lib/active_record/associations/association_scope.rb
index ab102b2b8f..6cc401e6cc 100644
--- a/activerecord/lib/active_record/associations/association_scope.rb
+++ b/activerecord/lib/active_record/associations/association_scope.rb
@@ -42,10 +42,6 @@ module ActiveRecord
           select_value ||= options[:uniq] && "DISTINCT #{reflection.quoted_table_name}.*"
         end
 
-        if reflection.macro == :has_and_belongs_to_many
-          select_value ||= reflection.klass.arel_table[Arel.star]
-        end
-
         select_value
       end
 
@@ -60,7 +56,7 @@ module ActiveRecord
 
             scope = scope.joins(join(
               join_table,
-              table[reflection.active_record_primary_key].
+              table[reflection.association_primary_key].
                 eq(join_table[reflection.association_foreign_key])
             ))
 
@@ -68,17 +64,28 @@ module ActiveRecord
           end
 
           if reflection.source_macro == :belongs_to
-            key         = reflection.association_primary_key
+            if reflection.options[:polymorphic]
+              key = reflection.association_primary_key(klass)
+            else
+              key = reflection.association_primary_key
+            end
+
             foreign_key = reflection.foreign_key
           else
             key         = reflection.foreign_key
             foreign_key = reflection.active_record_primary_key
           end
 
+          conditions = self.conditions[i]
+
           if reflection == chain.last
             scope = scope.where(table[key].eq(owner[foreign_key]))
 
-            conditions[i].each do |condition|
+            if reflection.type
+              scope = scope.where(table[reflection.type].eq(owner.class.base_class.name))
+            end
+
+            conditions.each do |condition|
               if options[:through] && condition.is_a?(Hash)
                 condition = { table.name => condition }
               end
@@ -87,12 +94,16 @@ module ActiveRecord
             end
           else
             constraint = table[key].eq(foreign_table[foreign_key])
-            join       = join(foreign_table, constraint)
 
-            scope = scope.joins(join)
+            if reflection.type
+              type = chain[i + 1].klass.base_class.name
+              constraint = constraint.and(table[reflection.type].eq(type))
+            end
+
+            scope = scope.joins(join(foreign_table, constraint))
 
-            unless conditions[i].empty?
-              scope = scope.where(sanitize(conditions[i], table))
+            unless conditions.empty?
+              scope = scope.where(sanitize(conditions, table))
             end
           end
         end