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首页 > 解决方案 > 在不影响旧迁移文件的情况下使用 Django-2 升级 wagtail-2。我得到这个“NoneType”对象没有属性“is_relation”

django - 在不影响旧迁移文件的情况下使用 Django-2 升级 wagtail-2。我得到这个“NoneType”对象没有属性“is_relation”

问题描述

我正在尝试将 wagtail-1.9 升级到 wagtail-2.0，将 Django-1.10.6 升级到 Django-2.0，但出现此错误。

    delay = not old_field.is_relation
    AttributeError: 'NoneType' object has no attribute 'is_relation'

我不想删除或重置我的旧迁移文件，因为如果我删除旧迁移文件或重置它，我将丢失我的数据。

这是错误的全部细节

Operations to perform:
  Apply all migrations: admin, auth, contenttypes, core, faq, home, mailqueue, sessions, taggit, testimonial, wagtailadmin, wagtailcore, wagtaildocs, wagtailembeds, wagtailforms, wagtailimages, wagtailredirects, wagtailsearch, wagtailusers
Traceback (most recent call last):
      File "manage.py", line 11, in <module>
        execute_from_command_line(sys.argv)
      File "/home/razia/.virtualenvs/web-dj2/lib/python3.6/site-packages/django/core/management/__init__.py", line 371, in execute_from_command_line
        utility.execute()
      File "/home/razia/.virtualenvs/web-dj2/lib/python3.6/site-packages/django/core/management/__init__.py", line 365, in execute
        self.fetch_command(subcommand).run_from_argv(self.argv)
      File "/home/razia/.virtualenvs/web-dj2/lib/python3.6/site-packages/django/core/management/base.py", line 288, in run_from_argv
        self.execute(*args, **cmd_options)
      File "/home/razia/.virtualenvs/web-dj2/lib/python3.6/site-packages/django/core/management/base.py", line 335, in execute
        output = self.handle(*args, **options)
      File "/home/razia/.virtualenvs/web-dj2/lib/python3.6/site-packages/django/core/management/commands/migrate.py", line 159, in handle
        pre_migrate_state = executor._create_project_state(with_applied_migrations=True)
      File "/home/razia/.virtualenvs/web-dj2/lib/python3.6/site-packages/django/db/migrations/executor.py", line 79, in _create_project_state
        migration.mutate_state(state, preserve=False)
      File "/home/razia/.virtualenvs/web-dj2/lib/python3.6/site-packages/django/db/migrations/migration.py", line 85, in mutate_state
        operation.state_forwards(self.app_label, new_state)
      File "/home/razia/.virtualenvs/web-dj2/lib/python3.6/site-packages/django/db/migrations/operations/fields.py", line 144, in state_forwards
        delay = not old_field.is_relation
    AttributeError: 'NoneType' object has no attribute 'is_relation'

标签： djangowagtail

解决方案

迁移有时需要一点人工干预。如果您正在单独开展一个项目，您可以通过使用 --fake-initial 选项运行新创建的迁移来声明“迁移破产”并从头开始重新创建迁移而不会丢失数据。

这里有更多细节，我建议先阅读它：

https://docs.djangoproject.com/en/2.0/topics/migrations/#initial-migrations

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