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Code Issues 32 Releases Wiki Activity

Fixed #33937 -- Optimized serialization of related m2m fields without natural keys.

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This commit is contained in:
Mark Evans
2022-09-03 09:53:58 -04:00
committed by Mariusz Felisiak
parent 604fadde11
commit 19e0587ee5
4 changed files with 42 additions and 2 deletions
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1
AUTHORS
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@@ -616,6 +616,7 @@ answer newbie questions, and generally made Django that much better:
Mario Gonzalez <gonzalemario@gmail.com>
Mariusz Felisiak <felisiak.mariusz@gmail.com>
Mark Biggers <biggers@utsl.com>
Mark Evans <mark@meltdownlabs.com>
Mark Gensler <mark.gensler@protonmail.com>
mark@junklight.com
Mark Lavin <markdlavin@gmail.com>

8
django/core/serializers/python.py
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@@ -70,14 +70,20 @@ class Serializer(base.Serializer):
def m2m_value(value):
return value.natural_key()
def queryset_iterator(obj, field):
return getattr(obj, field.name).iterator()
else:
def m2m_value(value):
return self._value_from_field(value, value._meta.pk)
def queryset_iterator(obj, field):
return getattr(obj, field.name).only("pk").iterator()
m2m_iter = getattr(obj, "_prefetched_objects_cache", {}).get(
field.name,
getattr(obj, field.name).iterator(),
queryset_iterator(obj, field),
)
self._current[field.name] = [m2m_value(related) for related in m2m_iter]

8
django/core/serializers/xml_serializer.py
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@@ -146,14 +146,20 @@ class Serializer(base.Serializer):
self.xml.endElement("natural")
self.xml.endElement("object")
def queryset_iterator(obj, field):
return getattr(obj, field.name).iterator()
else:
def handle_m2m(value):
self.xml.addQuickElement("object", attrs={"pk": str(value.pk)})
def queryset_iterator(obj, field):
return getattr(obj, field.name).only("pk").iterator()
m2m_iter = getattr(obj, "_prefetched_objects_cache", {}).get(
field.name,
getattr(obj, field.name).iterator(),
queryset_iterator(obj, field),
)
for relobj in m2m_iter:
handle_m2m(relobj)

27
tests/serializers/tests.py
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@@ -410,6 +410,33 @@ class SerializersTestBase:
self.assertEqual(self._get_field_values(child_data, "parent_m2m"), [])
self.assertEqual(self._get_field_values(child_data, "parent_data"), [])
def test_serialize_only_pk(self):
with self.assertNumQueries(5) as ctx:
serializers.serialize(
self.serializer_name,
Article.objects.all(),
use_natural_foreign_keys=False,
)
categories_sql = ctx[1]["sql"]
self.assertNotIn(connection.ops.quote_name("meta_data_id"), categories_sql)
meta_data_sql = ctx[2]["sql"]
self.assertNotIn(connection.ops.quote_name("kind"), meta_data_sql)
def test_serialize_no_only_pk_with_natural_keys(self):
with self.assertNumQueries(5) as ctx:
serializers.serialize(
self.serializer_name,
Article.objects.all(),
use_natural_foreign_keys=True,
)
categories_sql = ctx[1]["sql"]
self.assertNotIn(connection.ops.quote_name("meta_data_id"), categories_sql)
# CategoryMetaData has natural_key().
meta_data_sql = ctx[2]["sql"]
self.assertIn(connection.ops.quote_name("kind"), meta_data_sql)
class SerializerAPITests(SimpleTestCase):
def test_stream_class(self):