From e44ab5bb4fd3aa826ca4243a8ea9fd7125800da2 Mon Sep 17 00:00:00 2001 From: "Anton I. Sipos" Date: Sun, 4 Nov 2012 15:42:17 -0800 Subject: [PATCH] Fixed #18949 -- Improve performance of model_to_dict with many-to-many When calling model_to_dict, improve performance of the generated SQL by using values_list to determine primary keys of many to many objects. Add a specific test for this function, test_model_to_dict_many_to_many Thanks to brian for the original report and suggested fix. --- django/forms/models.py | 2 +- tests/modeltests/model_forms/tests.py | 36 +++++++++++++++++++++++++++ 2 files changed, 37 insertions(+), 1 deletion(-) diff --git a/django/forms/models.py b/django/forms/models.py index 11fe0c09ea..e9b71ccf26 100644 --- a/django/forms/models.py +++ b/django/forms/models.py @@ -126,7 +126,7 @@ def model_to_dict(instance, fields=None, exclude=None): data[f.name] = [] else: # MultipleChoiceWidget needs a list of pks, not object instances. - data[f.name] = [obj.pk for obj in f.value_from_object(instance)] + data[f.name] = list(f.value_from_object(instance).values_list('pk', flat=True)) else: data[f.name] = f.value_from_object(instance) return data diff --git a/tests/modeltests/model_forms/tests.py b/tests/modeltests/model_forms/tests.py index 947d0cf3c3..46d5af565a 100644 --- a/tests/modeltests/model_forms/tests.py +++ b/tests/modeltests/model_forms/tests.py @@ -561,6 +561,42 @@ class UniqueTest(TestCase): "slug": "Django 1.0"}, instance=p) self.assertTrue(form.is_valid()) +class ModelToDictTests(TestCase): + """ + Tests for forms.models.model_to_dict + """ + def test_model_to_dict_many_to_many(self): + categories=[ + Category(name='TestName1', slug='TestName1', url='url1'), + Category(name='TestName2', slug='TestName2', url='url2'), + Category(name='TestName3', slug='TestName3', url='url3') + ] + for c in categories: + c.save() + writer = Writer(name='Test writer') + writer.save() + + art = Article( + headline='Test article', + slug='test-article', + pub_date=datetime.date(1988, 1, 4), + writer=writer, + article='Hello.' + ) + art.save() + for c in categories: + art.categories.add(c) + art.save() + + with self.assertNumQueries(1): + d = model_to_dict(art) + + #Ensure all many-to-many categories appear in model_to_dict + for c in categories: + self.assertIn(c.pk, d['categories']) + #Ensure many-to-many relation appears as a list + self.assertIsInstance(d['categories'], list) + class OldFormForXTests(TestCase): def test_base_form(self): self.assertEqual(Category.objects.count(), 0)