Merge pull request #20552 from jamesdabbs/belongs-to-polymorphic-force-reload

Fix `undefined method uncached` for polymorphic belongs_to #20426

activerecord/CHANGELOG.md

+*   Prevent error when using `force_reload: true` on an unassigned polymorphic
+    belongs_to association.
+
+    Fixes #20426.
+
+    *James Dabbs*
+
 *   Correctly raise `ActiveRecord::AssociationTypeMismatch` when assigning
     a wrong type to a namespaced association.
 

activerecord/lib/active_record/associations/singular_association.rb

@@ -3,7 +3,7 @@ module Associations
     class SingularAssociation < Association #:nodoc:
       # Implements the reader method, e.g. foo.bar for Foo.has_one :bar
       def reader(force_reload = false)
-        if force_reload
+        if force_reload && klass
           klass.uncached { reload }
         elsif !loaded? || stale_target?
           reload

activerecord/test/cases/associations/belongs_to_associations_test.rb

@@ -318,9 +318,11 @@ def test_with_condition
   def test_polymorphic_association_class
     sponsor = Sponsor.new
     assert_nil sponsor.association(:sponsorable).send(:klass)
+    assert_nil sponsor.sponsorable(force_reload: true)
 
     sponsor.sponsorable_type = '' # the column doesn't have to be declared NOT NULL
     assert_nil sponsor.association(:sponsorable).send(:klass)
+    assert_nil sponsor.sponsorable(force_reload: true)
 
     sponsor.sponsorable = Member.new :name => "Bert"
     assert_equal Member, sponsor.association(:sponsorable).send(:klass)