Django动态过滤器故障 [英] Django dynamic filter failure

问题描述

作为此问题的后续操作，我d想查明发生的实际错误。我是在做错什么，还是一个错误？

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)

这两个查询应该相同，但不相同。

These two queries should be identical, but are not.

我的模型仅供参考：

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')

推荐答案

我发现查询之间有明显的区别。

I see an obvious difference between queries.

{'groups__isnull'：True } 永远不等于 {'groups__isnull'：'True'} 。

一个提供True为布尔值，另一个提供为字符串。

One provides True as boolean, other as a string.

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