尽管两个查询集在 shell 中打印出相同的结果，Django 的 assertQuerysetEqual() 方法还是失败了？

Question

我有一个Family和一个Session一对多的关系，这样一个实例family有一个session_set. 此外，Session还有一个session_number字段，它是一个整数。

我有两个Family,family1和 的实例family2，这样如果我session_set.order_by('session_number')在ipdb调试器中打印出它们，我就会发现它们看起来完全一样：

ipdb> family1.session_set.order_by('session_number')
<QuerySet [<Session: Welcome>, <Session: First-Time Parents: The Basics of Birth>, <Session: Initial Postpartum Lactation>, <Session: Sleep Techniques for New Babies>, <Session: Breastfeeding Preparation>, <Session: Newborn Care Basics>, <Session: Easing the Transition Back to Work>, <Session: Preparing for Parenting>, <Session: Decoding Baby Cues>, <Session: Postpartum Doula Support>, <Session: First-Time Parents: Birth Prep Q&A>, <Session: Postpartum Lactation Follow-Up>, <Session: Sleep Training for 4 Months & Beyond>, <Session: Mental Wellness in Pregnancy>, <Session: Infant CPR>, <Session: Prenatal Pelvic Physical Therapy>, <Session: Prenatal Massage>]>
ipdb> family2.session_set.order_by('session_number')
<QuerySet [<Session: Welcome>, <Session: First-Time Parents: The Basics of Birth>, <Session: Initial Postpartum Lactation>, <Session: Sleep Techniques for New Babies>, <Session: Breastfeeding Preparation>, <Session: Newborn Care Basics>, <Session: Easing the Transition Back to Work>, <Session: Preparing for Parenting>, <Session: Decoding Baby Cues>, <Session: Postpartum Doula Support>, <Session: First-Time Parents: Birth Prep Q&A>, <Session: Postpartum Lactation Follow-Up>, <Session: Sleep Training for 4 Months & Beyond>, <Session: Mental Wellness in Pregnancy>, <Session: Infant CPR>, <Session: Prenatal Pelvic Physical Therapy>, <Session: Prenatal Massage>]>

但是，如果我将这些查询集输入到 中，则会assertQuerysetEqual出现测试失败：

ipdb> self.assertQuerysetEqual(family1.session_set.order_by('session_number'), family2.session_set.order_by('session_number'))
*** AssertionError: Lists differ: ['<Session: Welcome>', '<Session: First-Ti[642 chars]ge>'] != [<Session: Welcome>, <Session: First-Time [608 chars]age>]

First differing element 0:
'<Session: Welcome>'
<Session: Welcome>

Diff is 2186 characters long. Set self.maxDiff to None to see it.

这是与maxDiffset to的更详细比较None：

ipdb> self.maxDiff = None
ipdb> self.assertQuerysetEqual(family1.session_set.order_by('session_number'), family2.session_set.order_by('session_number'))
*** AssertionError: Lists differ: ['<Session: Welcome>', '<Session: First-Ti[642 chars]ge>'] != [<Session: Welcome>, <Session: First-Time [608 chars]age>]

First differing element 0:
'<Session: Welcome>'
<Session: Welcome>

- ['<Session: Welcome>',
?  -                  -

+ [<Session: Welcome>,
-  '<Session: First-Time Parents: The Basics of Birth>',
?  -                                                  -

+  <Session: First-Time Parents: The Basics of Birth>,
-  '<Session: Initial Postpartum Lactation>',
?  -                                       -

+  <Session: Initial Postpartum Lactation>,
-  '<Session: Sleep Techniques for New Babies>',
?  -                                          -

+  <Session: Sleep Techniques for New Babies>,
-  '<Session: Breastfeeding Preparation>',
?  -                                    -

+  <Session: Breastfeeding Preparation>,
-  '<Session: Newborn Care Basics>',
?  -                              -

+  <Session: Newborn Care Basics>,
-  '<Session: Easing the Transition Back to Work>',
?  -                                             -

+  <Session: Easing the Transition Back to Work>,
-  '<Session: Preparing for Parenting>',
?  -                                  -

+  <Session: Preparing for Parenting>,
-  '<Session: Decoding Baby Cues>',
?  -                             -

+  <Session: Decoding Baby Cues>,
-  '<Session: Postpartum Doula Support>',
?  -                                   -

+  <Session: Postpartum Doula Support>,
-  '<Session: First-Time Parents: Birth Prep Q&A>',
?  -                                             -

+  <Session: First-Time Parents: Birth Prep Q&A>,
-  '<Session: Postpartum Lactation Follow-Up>',
?  -                                         -

+  <Session: Postpartum Lactation Follow-Up>,
-  '<Session: Sleep Training for 4 Months & Beyond>',
?  -                                               -

+  <Session: Sleep Training for 4 Months & Beyond>,
-  '<Session: Mental Wellness in Pregnancy>',
?  -                                       -

+  <Session: Mental Wellness in Pregnancy>,
-  '<Session: Infant CPR>',
?  -                     -

+  <Session: Infant CPR>,
-  '<Session: Prenatal Pelvic Physical Therapy>',
?  -                                           -

+  <Session: Prenatal Pelvic Physical Therapy>,
-  '<Session: Prenatal Massage>']
?  -                           -

+  <Session: Prenatal Massage>]

这些比较似乎“不同步”。然而，这session_number也是一样的：

ipdb> [(session.session_number, str(session.session_type)) for session in family1.session_set.order_by('session_number')]
[(0, 'Welcome'), (1, 'First-Time Parents: The Basics of Birth'), (2, 'Initial Postpartum Lactation'), (3, 'Sleep Techniques for New Babies'), (4, 'Breastfeeding Preparation'), (5, 'Newborn Care Basics'), (6, 'Easing the Transition Back to Work'), (7, 'Preparing for Parenting'), (8, 'Decoding Baby Cues'), (9, 'Postpartum Doula Support'), (10, 'First-Time Parents: Birth Prep Q&A'), (11, 'Postpartum Lactation Follow-Up'), (12, 'Sleep Training for 4 Months & Beyond'), (13, 'Mental Wellness in Pregnancy'), (14, 'Infant CPR'), (15, 'Prenatal Pelvic Physical Therapy'), (16, 'Prenatal Massage')]
ipdb> [(session.session_number, str(session.session_type)) for session in family2.session_set.order_by('session_number')]
[(0, 'Welcome'), (1, 'First-Time Parents: The Basics of Birth'), (2, 'Initial Postpartum Lactation'), (3, 'Sleep Techniques for New Babies'), (4, 'Breastfeeding Preparation'), (5, 'Newborn Care Basics'), (6, 'Easing the Transition Back to Work'), (7, 'Preparing for Parenting'), (8, 'Decoding Baby Cues'), (9, 'Postpartum Doula Support'), (10, 'First-Time Parents: Birth Prep Q&A'), (11, 'Postpartum Lactation Follow-Up'), (12, 'Sleep Training for 4 Months & Beyond'), (13, 'Mental Wellness in Pregnancy'), (14, 'Infant CPR'), (15, 'Prenatal Pelvic Physical Therapy'), (16, 'Prenatal Massage')]

为什么这里assertQuerysetEqual没有按预期工作？

Answer 1

这是因为assertQuerysetEqual不会将查询集与另一个查询集进行比较，而是将查询集与值列表进行比较。

来自assertQuerysetEqual的文档：

TransactionTestCase.assertQuerysetEqual（qs，值，transform=repr，ordered=True，msg=None）

断言查询集qs返回特定的值列表values。

qs和的内容的比较values是使用函数transform进行的；默认情况下，这意味着比较每个值的 repr() 。

因此，您应该将第二个参数转换为列表：

self.assertQuerysetEqual(family1.session_set.order_by('session_number'), list(family2.session_set.order_by('session_number')))