Question

这是我创建的第一个模型

class IPAddresses(models.Model):
    '''
    @brief      Class for ip addresses.
    @attrs      name        Can be company name
    '''

    ip = models.GenericIPAddressField()
    name = models.CharField(max_length=150, null=True, blank=True)
    active = models.BooleanField(default=True)

    def __unicode__(self):
        return self.ip



class Authentication(models.Model):
    '''
    @brief      Custom Authentication for dashboard
    @attrs      name    can be a name of a person
    '''


    name = models.CharField(max_length=100, null=True, blank=True)
    password = models.CharField(max_length=200, unique=True)
    ip = models.ManyToManyField(IPAddresses, blank=True)

但是，我将＆＃39; IP地址＆＃39; 的型号名称更改为＆＃39; IPAddress＆＃39; 并运行迁移。这很好但是我的下一次迁移不是并且一直收到此值错误：

  Apply all migrations: admin, auth, cache_admin, contenttypes, core, provider, saba_dashboard, sessions
Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/deanchristianarmada/Desktop/projects/asian_gaming/radar/lib/python2.7/site-packages/django/core/management/__init__.py", line 367, in execute_from_command_line
    utility.execute()
  File "/Users/deanchristianarmada/Desktop/projects/asian_gaming/radar/lib/python2.7/site-packages/django/core/management/__init__.py", line 359, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/deanchristianarmada/Desktop/projects/asian_gaming/radar/lib/python2.7/site-packages/django/core/management/base.py", line 294, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/Users/deanchristianarmada/Desktop/projects/asian_gaming/radar/lib/python2.7/site-packages/django/core/management/base.py", line 345, in execute
    output = self.handle(*args, **options)
  File "/Users/deanchristianarmada/Desktop/projects/asian_gaming/radar/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 164, in handle
    pre_migrate_apps = pre_migrate_state.apps
  File "/Users/deanchristianarmada/Desktop/projects/asian_gaming/radar/lib/python2.7/site-packages/django/utils/functional.py", line 35, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/Users/deanchristianarmada/Desktop/projects/asian_gaming/radar/lib/python2.7/site-packages/django/db/migrations/state.py", line 176, in apps
    return StateApps(self.real_apps, self.models)
  File "/Users/deanchristianarmada/Desktop/projects/asian_gaming/radar/lib/python2.7/site-packages/django/db/migrations/state.py", line 249, in __init__
    raise ValueError("\n".join(error.msg for error in errors))
ValueError: The field saba_dashboard.Authentication.ip was declared with a lazy reference to 'core.ipaddresses', but app 'core' doesn't provide model 'ipaddresses'.
The field saba_dashboard.Authentication_ip.ipaddresses was declared with a lazy reference to 'core.ipaddresses', but app 'core' doesn't provide model 'ipaddresses'.

如何解决此问题？

我正在使用：

Django 1.10.5
Postgresql
Python 2.7

Answer 1

我自己正在努力解决这样的僵局，继续得到“ValueError：字段......被宣布为懒惰引用'...'，但app'......'不提供模型'.. '。“

在深入pgadmin并删除/恢复一些表后，我实际上发现它也可以通过添加一个新的迁移来解决，该迁移告诉django所引用的模型已经改变：

    migrations.AlterField(
        model_name='...',
        name='...',
        field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='...', to='<app>.<new-model>'), <===
    ),

此外，我必须正确设置应用程序之间的依赖关系，因此，例如，AlterField应该依赖于显然创建该模型的迁移。不要问我为什么它不能开箱即用，我只需要经历这个....

保

Answer 2

解决方案是访问数据库中的django_migrations表并删除导致此错误的迁移。然后转到特定的应用迁移文件夹并删除特定的迁移

这是最后一个选项 ./manage.py migrate specific_app <specific_migration_to_rollback_to>无效，这是django 1.10版本中的常见问题

Answer 3

Django 1.11解决了这个问题。（或者至少，它适合我。）

Answer 4

我的问题是PyCharm的重构有点激进，并更改了实际迁移文件中的模型参考。恢复了已更改的迁移，并能够继续进行。

以防万一这有助于使用较新版本的Django（通常可以正常处理模型重命名）的任何人。

Django ValueError：＆＃39; dtedeclared与懒惰引用.....＆＃39;更改模型名称时

4 个答案: