Fix problem where wrong keys are used in JoinAssociation when an association goes :through a belongs_to [#2801 state:resolved]

2 files changed, 16 insertions, 9 deletions

diff --git a/activerecord/lib/active_record/associations/class_methods/join_dependency/join_association.rb b/activerecord/lib/active_record/associations/class_methods/join_dependency/join_association.rb
index 694778008b..02707dfae1 100644
--- a/activerecord/lib/active_record/associations/class_methods/join_dependency/join_association.rb
+++ b/activerecord/lib/active_record/associations/class_methods/join_dependency/join_association.rb
@@ -190,17 +190,20 @@ module ActiveRecord
             ).alias @aliased_join_table_name
 
             jt_conditions = []
-            jt_foreign_key = first_key = second_key = nil
+            first_key = second_key = nil
 
-            if through_reflection.options[:as] # has_many :through against a polymorphic join
-              as_key         = through_reflection.options[:as].to_s
-              jt_foreign_key = as_key + '_id'
-
-              jt_conditions <<
-              join_table[as_key + '_type'].
-                eq(parent.active_record.base_class.name)
+            if through_reflection.macro == :belongs_to
+              jt_primary_key = through_reflection.primary_key_name
+              jt_foreign_key = through_reflection.association_primary_key
             else
+              jt_primary_key = through_reflection.active_record_primary_key
               jt_foreign_key = through_reflection.primary_key_name
+
+              if through_reflection.options[:as] # has_many :through against a polymorphic join
+                jt_conditions <<
+                join_table["#{through_reflection.options[:as]}_type"].
+                  eq(parent.active_record.base_class.name)
+              end
             end
 
             case source_reflection.macro
@@ -233,7 +236,7 @@ module ActiveRecord
             end
 
             jt_conditions <<
-            parent_table[parent.primary_key].
+            parent_table[jt_primary_key].
               eq(join_table[jt_foreign_key])
 
             if through_reflection.options[:conditions]
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index b9caa64a0e..70165c600e 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -208,6 +208,10 @@ module ActiveRecord
         @association_foreign_key ||= options[:association_foreign_key] || class_name.foreign_key
       end
 
+      def association_primary_key
+        @association_primary_key ||= options[:primary_key] || klass.primary_key
+      end
+
       def active_record_primary_key
         @active_record_primary_key ||= options[:primary_key] || active_record.primary_key
       end