Python Django模型继承奇怪还是预期的行为?
我目前正在使用django 1.11进行一个项目,并且花了一些时间试图找到错误的原因。我不知道这是一个bug还是预期的行为,我希望有人能对这个问题有所了解,或者给我指出正确的方向。我已经搜索过类似的问题,但没有发现任何类似的问题 问题如下,我有一个基本模型类:Python Django模型继承奇怪还是预期的行为?,python,django,python-3.x,Python,Django,Python 3.x,我目前正在使用django 1.11进行一个项目,并且花了一些时间试图找到错误的原因。我不知道这是一个bug还是预期的行为,我希望有人能对这个问题有所了解,或者给我指出正确的方向。我已经搜索过类似的问题,但没有发现任何类似的问题 问题如下,我有一个基本模型类: class BaseModel(models.Model): id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False) cre
class BaseModel(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
created_at = models.DateTimeField(default=timezone.now, editable=False)
modified_at = models.DateTimeField(default=timezone.now, editable=False)
def save(self, *args, **kwargs):
if self.pk:
self.modified_at = timezone.now
return super(BaseModel, self).save(*args, **kwargs)
在我需要覆盖另一个模型上的默认保存行为之前,它在每个模型上都可以正常工作:
class Agent(BaseModel):
TIME_ZONES = [(tz, tz) for tz in pytz.common_timezones]
user = models.OneToOneField(
User,
on_delete=models.CASCADE,
related_name='agent',
)
time_zone = models.CharField(choices=TIME_ZONES,
default=settings.TIME_ZONE,
max_length=100)
phone = models.CharField(max_length=50, null=True, blank=True)
email = models.CharField(max_length=255, null=True, blank=True)
def __str__(self):
return self.user.username
def save(self, *args, **kwargs):
self.email = self.user.email
return super(Agent, self).save(*args, **kwargs)
当我试图将代理
模型的一个新实例保存到db doing代理(user=user).save()
时,出现了一个异常,表示预期的字符串或类似于object的字节
如果我执行以下操作之一,则不会引发异常:
- 将
模型更改为直接从代理
并在代理`类中声明模型继承。模型
处创建的和
处修改的
- 将
类的save方法上的super调用更改为Agent
并且仍然继承自super(BaseModel,self).super(*args,**kwargs)
BaseModel
Traceback:
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
41. response = get_response(request)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
187. response = self.process_exception_by_middleware(e, request)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
185. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/views/decorators/csrf.py" in wrapped_view
58. return view_func(*args, **kwargs)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/views/generic/base.py" in view
68. return self.dispatch(request, *args, **kwargs)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/utils/decorators.py" in _wrapper
67. return bound_func(*args, **kwargs)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/views/decorators/debug.py" in sensitive_post_parameters_wrapper
76. return view(request, *args, **kwargs)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/utils/decorators.py" in bound_func
63. return func.__get__(self, type(self))(*args2, **kwargs2)
File "/var/task/backend/users/views/sign_up.py" in dispatch
19. return super(SignUpViewSet, self).dispatch(*args, **kwargs)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/rest_framework/views.py" in dispatch
483. response = self.handle_exception(exc)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/rest_framework/views.py" in handle_exception
443. self.raise_uncaught_exception(exc)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/rest_framework/views.py" in dispatch
480. response = handler(request, *args, **kwargs)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/rest_framework/generics.py" in post
192. return self.create(request, *args, **kwargs)
File "/var/task/backend/users/views/sign_up.py" in create
31. user = self.perform_create(serializer)
File "/var/task/backend/users/views/sign_up.py" in perform_create
41. user = serializer.save(self.request)
File "/var/task/backend/users/serializers/sign_up.py" in save
40. agent.save()
File "/var/task/backend/users/models/agent.py" in save
31. return super(Agent, self).save(*args, **kwargs)
File "/var/task/backend/core/models.py" in save
69. return super(BaseModel, self).save(*args, **kwargs)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/base.py" in save
806. force_update=force_update, update_fields=update_fields)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/base.py" in save_base
836. updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/base.py" in _save_table
903. forced_update)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/base.py" in _do_update
953. return filtered._update(values) > 0
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/query.py" in _update
661. return query.get_compiler(self.db).execute_sql(CURSOR)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/sql/compiler.py" in execute_sql
1191. cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/sql/compiler.py" in execute_sql
863. sql, params = self.as_sql()
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/sql/compiler.py" in as_sql
1157. val = field.get_db_prep_save(val, connection=self.connection)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/fields/__init__.py" in get_db_prep_save
766. prepared=False)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/fields/__init__.py" in get_db_prep_value
1455. value = self.get_prep_value(value)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/fields/__init__.py" in get_prep_value
1434. value = super(DateTimeField, self).get_prep_value(value)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/fields/__init__.py" in get_prep_value
1292. return self.to_python(value)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/db/models/fields/__init__.py" in to_python
1395. parsed = parse_datetime(value)
File "/root/.virtualenvs/ve/lib/python3.6/site-packages/django/utils/dateparse.py" in parse_datetime
94. match = datetime_re.match(value)
Exception Type: TypeError at /api/v1/auth/sign-up/
Exception Value: expected string or bytes-like object
这是你的问题。你想做的是
timezone.now()
。当从函数引用而不是字符串或datetime对象解析日期时,它会崩溃。如果您从BaseModel
类中绕过save方法,则不会触发该行为。哦,我现在觉得自己像个傻瓜,我想我已经注意到了这一点,非常感谢!“它在每个模型上都工作得很好”=>显然不是,参见公认的答案。@Brunodesshuilliers发现其他模型正在使用另一个父类,而从BaseModel继承的另一个模型正在调用super绕过BaseModel类上的save方法。这段代码是别人写的,但没有看到这一点完全是我的错。
self.modified_at = timezone.now