python，django，向mysql更新数据时save()报错不能用

[水炮]

求大神帮忙，models.py中有个Student类，当我用s = Student(...)创建对象,然后s.save()可以往mysql中插入记录,但是当我用 s.name = 'aaa',想更新的时候,调用s.save()就报错了.错误代码如下,望大家解答一下.

>>> s.save()
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "D:\Program Files (x86)\Python27\lib\site-packages\django\db\models\base.
py", line 431, in save
self.save_base(force_insert=force_insert, force_update=force_update)
File "D:\Program Files (x86)\Python27\lib\site-packages\django\db\models\base.
py", line 495, in save_base
rows = manager.filter(pk=pk_val)._update(values)
File "D:\Program Files (x86)\Python27\lib\site-packages\django\db\models\query
.py", line 446, in _update
query.add_update_fields(values)
File "D:\Program Files (x86)\Python27\lib\site-packages\django\db\models\sql\s
ubqueries.py", line 249, in add_update_fields
val = field.get_db_prep_save(val)
File "D:\Program Files (x86)\Python27\lib\site-packages\django\db\models\field
s\__init__.py", line 202, in get_db_prep_save
return self.get_db_prep_value(value)
File "D:\Program Files (x86)\Python27\lib\site-packages\django\db\models\field
s\__init__.py", line 446, in get_db_prep_value
return self.to_python(value)
File "D:\Program Files (x86)\Python27\lib\site-packages\django\db\models\field
s\__init__.py", line 442, in to_python
ugettext_lazy("This field cannot be null."))
ValidationError: <django.utils.functional.__proxy__ object at 0x0000000002F26320
>

[cimi5210]

你调用save的时候，有的字段值为空了，建议用下面的update方法 ModelName.objects.filter(id=1).update(name='aaa')

[CrySleeper]

贴一些代码吧，感觉好像是你的model object已经离开了执行的上下文