Django动态过滤失败
作为这个问题的后续，我想查明实际发生的错误。我做错了什么，还是这是一个错误？
f = {'groups__isnull': 'True'}
students1 = models.Student.objects.filter( **f )
students2 = models.Student.objects.filter(groups__isnull=True)
这两个查询应该相同，但事实并非如此。
作为参考，我的模型：
class Student (models.Model):
user = models.ForeignKey(User, unique=True, null=False, related_name='student')
teacher = models.ForeignKey(User, null=False, related_name='students')
assignment = models.ForeignKey(LabJournal, blank=True, null=True, related_name='students')
class JournalGroup (models.Model):
title = models.CharField(null=False, max_length=256)
owner = models.ForeignKey(User, null=True, related_name='journal_groups')
members = models.ManyToManyField(Student, blank=True, related_name='groups')
As a follow-up to this question, I'd like to pinpoint the actual error that was occurring. Am I doing something wrong, or is this a bug?
f = {'groups__isnull': 'True'}
students1 = models.Student.objects.filter( **f )
students2 = models.Student.objects.filter(groups__isnull=True)
These two queries should be identical, but are not.
For reference, my models:
class Student (models.Model):
user = models.ForeignKey(User, unique=True, null=False, related_name='student')
teacher = models.ForeignKey(User, null=False, related_name='students')
assignment = models.ForeignKey(LabJournal, blank=True, null=True, related_name='students')
class JournalGroup (models.Model):
title = models.CharField(null=False, max_length=256)
owner = models.ForeignKey(User, null=True, related_name='journal_groups')
members = models.ManyToManyField(Student, blank=True, related_name='groups')
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评论（1）
我发现查询之间存在明显差异。
{'groups__isnull': True}永远不等于{'groups__isnull': 'True'}。一种将 True 作为布尔值提供，另一种将 True 作为字符串提供。
I see an obvious difference between queries.
{'groups__isnull': True}is never equal to{'groups__isnull': 'True'}.One provides True as boolean, other as a string.