Fix preloading through association with custom scope

If `reflection_scope.where_clause` is not empty, `through_scope` should
be joined the source association. But if `values[:references]` in
`reflection_scope` is empty, the source association will not be joined.
It should use `source_reflection.table_name` in that case.

Fixes #22535.
Closes #28763.

2 files changed, 11 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/associations/preloader/through_association.rb b/activerecord/lib/active_record/associations/preloader/through_association.rb
index b469a9ca10..f0a2e88c53 100644
--- a/activerecord/lib/active_record/associations/preloader/through_association.rb
+++ b/activerecord/lib/active_record/associations/preloader/through_association.rb
@@ -94,6 +94,12 @@ module ActiveRecord
                 scope.includes!(source_reflection.name)
               end
 
+              if values[:references] && !values[:references].empty?
+                scope.references!(values[:references])
+              else
+                scope.references!(source_reflection.table_name)
+              end
+
               if joins = values[:joins]
                 scope.joins!(source_reflection.name => joins)
               end
@@ -102,7 +108,6 @@ module ActiveRecord
                 scope.left_outer_joins!(source_reflection.name => left_outer_joins)
               end
 
-              scope.references! values[:references]
               if scope.eager_loading? && order_values = values[:order]
                 scope = scope.order(order_values)
               end
diff --git a/activerecord/test/cases/associations/eager_test.rb b/activerecord/test/cases/associations/eager_test.rb
index 9fb395853e..3fd2c73efc 100644
--- a/activerecord/test/cases/associations/eager_test.rb
+++ b/activerecord/test/cases/associations/eager_test.rb
@@ -1307,6 +1307,11 @@ class EagerAssociationTest < ActiveRecord::TestCase
     assert_equal projects.last.mentor.developers.first.contracts, projects.last.developers.last.contracts
   end
 
+  def test_preloading_has_many_through_with_custom_scope
+    project = Project.includes(:developers_named_david_with_hash_conditions).find(projects(:active_record).id)
+    assert_equal [developers(:david)], project.developers_named_david_with_hash_conditions
+  end
+
   test "scoping with a circular preload" do
     assert_equal Comment.find(1), Comment.preload(post: :comments).scoping { Comment.find(1) }
   end