当我使用django时，我python manage.py migrate在执行后遇到以下错误python manage.py makemigrations
File "manage.py", line 22, in <module>
execute_from_command_line(sys.argv)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
utility.execute()
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/core/management/__init__.py", line 375, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/core/management/base.py", line 323, in run_from_argv
self.execute(*args, **cmd_options)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/core/management/base.py", line 364, in execute
output = self.handle(*args, **options)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/core/management/base.py", line 83, in wrapped
res = handle_func(*args, **kwargs)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/core/management/commands/migrate.py", line 234, in handle
fake_initial=fake_initial,
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/migrations/executor.py", line 117, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/migrations/executor.py", line 147, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/migrations/executor.py", line 245, in apply_migration
state = migration.apply(state, schema_editor)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/migrations/migration.py", line 124, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/migrations/operations/fields.py", line 112, in database_forwards
field,
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/backends/base/schema.py", line 433, in add_field
definition, params = self.column_sql(model, field, include_default=True)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/backends/base/schema.py", line 161, in column_sql
default_value = self.effective_default(field)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/backends/base/schema.py", line 233, in effective_default
return field.get_db_prep_save(self._effective_default(field), self.connection)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/models/fields/__init__.py", line 789, in get_db_prep_save
return self.get_db_prep_value(value, connection=connection, prepared=False)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/models/fields/__init__.py", line 1429, in get_db_prep_value
value = self.get_prep_value(value)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/models/fields/__init__.py", line 1408, in get_prep_value
value = super().get_prep_value(value)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/models/fields/__init__.py", line 1268, in get_prep_value
return self.to_python(value)
File "/Users/rasikraj/Desktop/eb-virt/lib/python3.7/site-packages/django/db/models/fields/__init__.py", line 1393, in to_python
params={'value': value},
django.core.exceptions.ValidationError: ["'' value has an invalid format. It must be in YYYY-MM-DD HH:MM[:ss[.uuuuuu]][TZ] format."]
什么可能是导致此错误的原因，以及如何解决此问题。我正在使用python 3.7和Django 2.2
基于该错误，存在一个DateTimeField[Django-doc]和一个default=''[Django-doc]。但这不是一个有效的默认值：aDateTimeField应该已经在数据库中存储了一个日期时间（或者None如果该字段是NULL-able的话）。
因此，您应该为此提供有效的默认值DateTimeField，例如：
from django.utils import timezone
class SomeModel(models.Model):
my_field = DateTimeField(default=timezone.now)或者，您可以省略默认值，然后运行makemigrations。在这种情况下，Django将询问您是否要提供一次性的默认值，该默认值将应用于数据库中已有的记录。
更改字段后，您需要删除在添加（或更改）该字段时构建的（无效）迁移文件，并使用进行新的迁移manage.py makemigrations。毕竟，在构造迁移文件时不会进行此验证，现在您进行迁移确实会出错。如果您以后更改模型，仍然不会执行无效的迁移填充，因此它将再次引发相同的错误。
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