Respect custom primary keys for associations in `Relation#where`

While we query the proper columns, we go through normal handling for
converting the value to a primitive which assumes it should use the
table's primary key. If the association specifies a different value (and
we know that we're working with an association), we should use the
custom primary key instead.

Fixes #18813.

1 files changed, 21 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/relation/predicate_builder/association_query_handler.rb b/activerecord/lib/active_record/relation/predicate_builder/association_query_handler.rb
index aabcf20c1d..159889d3b8 100644
--- a/activerecord/lib/active_record/relation/predicate_builder/association_query_handler.rb
+++ b/activerecord/lib/active_record/relation/predicate_builder/association_query_handler.rb
@@ -31,7 +31,14 @@ module ActiveRecord
       end
 
       def ids
-        value
+        case value
+        when Relation
+          value.select(primary_key)
+        when Array
+          value.map { |v| convert_to_id(v) }
+        else
+          convert_to_id(value)
+        end
       end
 
       def base_class
@@ -42,6 +49,10 @@ module ActiveRecord
 
       private
 
+      def primary_key
+        associated_table.association_primary_key(base_class)
+      end
+
       def polymorphic_base_class_from_value
         case value
         when Relation
@@ -53,6 +64,15 @@ module ActiveRecord
           value.class.base_class
         end
       end
+
+      def convert_to_id(value)
+        case value
+        when Base
+          value._read_attribute(primary_key)
+        else
+          value
+        end
+      end
     end
   end
 end