Question

class Event(models.Model):
    student = models.ForeignKey(User)
    startTime = models.DateTimeField('Start Time')
    endTime = models.DateTimeField('End Time')

def __str__(self):              
    return str(self.student)

以上是我设置Event表的模型。我已经设置好了，因此从Django网站上的管理员用户中提取了外键“学生”。

当我运行Event.objects.all()时：

[<Event: test.student1>]

哪个好。

当我运行Event.objects.get(student='test.student1')时：

Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/usr/local/lib/python2.7/dist-packages/django/db/models/manager.py", line 127, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 325, in get
clone = self.filter(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 679, in filter
return self._filter_or_exclude(False, *args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 697, in _filter_or_exclude
clone.query.add_q(Q(*args, **kwargs))
File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1304, in add_q
clause, require_inner = self._add_q(where_part, self.used_aliases)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1332, in _add_q
allow_joins=allow_joins, split_subq=split_subq,
File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1194, in build_filter
lookups, value)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/related.py", line 1740, in get_lookup_constraint
lookup_class(target.get_col(alias, source), val), AND)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/lookups.py", line 96, in __init__
self.rhs = self.get_prep_lookup()
File "/usr/local/lib/python2.7/dist-packages/django/db/models/lookups.py", line 134, in get_prep_lookup
return self.lhs.output_field.get_prep_lookup(self.lookup_name, self.rhs)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/__init__.py", line 727, in get_prep_lookup
return self.get_prep_value(value)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/__init__.py", line 985, in get_prep_value
return int(value)
ValueError: invalid literal for int() with base 10: 'test.student1'

我觉得问题与学生是Users表中的外键有关（我从django.contrib.auth.models导入用户导入）。我不能为我的生活弄清楚我做错了什么。

Answer 1

student属性是外键（整数），您需要搜索学生的用户名。

Event.objects.get(student__username='test.student1')

Answer 2

通过Event查找student时，您必须传递实际的student个实例。

Event.objects.get(student=student_instance)

您的案例中发生了什么：

对于模型Student（源自Django的User模型），__str__()方法返回username。因此，当您在str(self.student)模型的__str__()方法中执行Event时，您将获得username实例的student。您假设test.student1是学生实例，但实际上是学生实例的username。

将您的查询更改为通过学生用户名student__username进行访问，并且它应该有效。

Event.objects.get(student__username='test.student1')

在Django中查询sqlite db时的ValueError

2 个答案: