【发布时间】：2015-06-15 10:47:06
【问题描述】：
尝试将项目从 Django 1.7 迁移到 1.8。在与代码错误搏斗之后，我能够运行迁移。但是，当我尝试迁移时，我收到错误“'NoneType' object has no attribute '_meta'”
在回溯中没有对我的任何应用程序的引用，所以我不确定在哪里寻找错误（以及在此处包含哪些代码，以便我可以为那些试图提供帮助的人提供更多帮助）我）
这是回溯的全文
(venv)rtownley@ubuntu:~/Projects/sparrow1/NJ$ ./manage.py makemigrations
No changes detected
(venv)rtownley@ubuntu:~/Projects/sparrow1/NJ$ ./manage.py migrate
Operations to perform:
Synchronize unmigrated apps: staticfiles, editor, djcelery, messages, getty, kombu_transport_django, debug_toolbar, utils, locking, petro, tokenapi, grappelli, django_extensions, selectable
Apply all migrations: adops, taxonomy, issues, editorial, contenttypes, authors, auth, comms, membership, sessions, bento, urlalias, accounts, breaking_news, easy_thumbnails, images, admin, pages, documents, events
Synchronizing apps without migrations:
Creating tables...
Running deferred SQL...
Installing custom SQL...
Running migrations:
Rendering model states...Traceback (most recent call last):
File "./manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/home/rtownley/Projects/sparrow1/venv/lib/python3.4/site-packages/django/core/management/__init__.py", line 338, in execute_from_command_line
utility.execute()
File "/home/rtownley/Projects/sparrow1/venv/lib/python3.4/site-packages/django/core/management/__init__.py", line 330, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/rtownley/Projects/sparrow1/venv/lib/python3.4/site-packages/django/core/management/base.py", line 390, in run_from_argv
self.execute(*args, **cmd_options)
File "/home/rtownley/Projects/sparrow1/venv/lib/python3.4/site-packages/django/core/management/base.py", line 441, in execute
output = self.handle(*args, **options)
File "/home/rtownley/Projects/sparrow1/venv/lib/python3.4/site-packages/django/core/management/commands/migrate.py", line 221, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File "/home/rtownley/Projects/sparrow1/venv/lib/python3.4/site-packages/django/db/migrations/executor.py", line 104, in migrate
state = migration.mutate_state(state, preserve=do_run)
File "/home/rtownley/Projects/sparrow1/venv/lib/python3.4/site-packages/django/db/migrations/migration.py", line 83, in mutate_state
operation.state_forwards(self.app_label, new_state)
File "/home/rtownley/Projects/sparrow1/venv/lib/python3.4/site-packages/django/db/migrations/operations/fields.py", line 51, in state_forwards
state.reload_model(app_label, self.model_name_lower)
File "/home/rtownley/Projects/sparrow1/venv/lib/python3.4/site-packages/django/db/migrations/state.py", line 97, in reload_model
related_models = get_related_models_recursive(old_model)
File "/home/rtownley/Projects/sparrow1/venv/lib/python3.4/site-packages/django/db/migrations/state.py", line 57, in get_related_models_recursive
rel_app_label, rel_model_name = rel_mod._meta.app_label, rel_mod._meta.model_name
AttributeError: 'NoneType' object has no attribute '_meta'
其他可能发挥作用的部分： -我有一个自定义处理程序，它监听保存事件，序列化数据，并在 Mongo 中创建一个相同的对象 - 在运行 Python3.4 的虚拟环境中运行
关于去哪里寻找错误有什么想法吗？谢谢，很抱歉我还不能提供更多代码！
【问题讨论】：
-
显示迁移代码也有很长的路要走。
-
看起来您的某个模型可能与不存在的模型相关？
-
呃呃就是这样。我删除的模型在 Git 合并期间被另一个人重新添加。感谢您让我走上正轨！