Fixed #373 -- Added CompositePrimaryKey.

Thanks Lily Foote and Simon Charette for reviews and mentoring
this Google Summer of Code 2024 project.

Co-authored-by: Simon Charette <charette.s@gmail.com>
Co-authored-by: Lily Foote <code@lilyf.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/django/core/serializers/python.py b/django/core/serializers/python.py
index 46ef9f0771..57edebbb70 100644
--- a/django/core/serializers/python.py
+++ b/django/core/serializers/python.py
@@ -7,6 +7,7 @@ other serializers.
 from django.apps import apps
 from django.core.serializers import base
 from django.db import DEFAULT_DB_ALIAS, models
+from django.db.models import CompositePrimaryKey
 from django.utils.encoding import is_protected_type
 
 
@@ -39,6 +40,8 @@ class Serializer(base.Serializer):
         return data
 
     def _value_from_field(self, obj, field):
+        if isinstance(field, CompositePrimaryKey):
+            return [self._value_from_field(obj, f) for f in field]
         value = field.value_from_object(obj)
         # Protected types (i.e., primitives like None, numbers, dates,
         # and Decimals) are passed through as is. All other values are