ValueError:在Djang中解包的值太多（应为2）

Question

我正在重新组织我的一个项目，使其更具可重用性，并且总体结构更好，现在每当我运行makemigrations时，都会出现下面的错误-我花了半天的时间试图自己解决这个问题，但在搜索上的Google结果用完了，需要一些帮助。我所做的是删除一个自定义的用户模型，这样我就可以使用Django的内置用户模型，我还为我的应用程序命名了url。我不想包括一堆代码，但这将不会做什么，但弄脏了这篇文章，因为我希望回溯有线索，我没有看到。如果你正在看这个，并且知道什么可能是错误的罪魁祸首，你能就你需要看到什么提供帮助提出建议吗？谢谢您。

    Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/core/management/__init__.py", line 353, in execute_from_command_line
    utility.execute()
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/core/management/__init__.py", line 345, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/core/management/base.py", line 348, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/core/management/base.py", line 399, in execute
    output = self.handle(*args, **options)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/core/management/commands/makemigrations.py", line 132, in handle
    migration_name=self.migration_name,
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/migrations/autodetector.py", line 45, in changes
    changes = self._detect_changes(convert_apps, graph)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/migrations/autodetector.py", line 128, in _detect_changes
    self.old_apps = self.from_state.concrete_apps
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/migrations/state.py", line 166, in concrete_apps
    self.apps = StateApps(self.real_apps, self.models, ignore_swappable=True)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/migrations/state.py", line 228, in __init__
    self.render_multiple(list(models.values()) + self.real_models)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/migrations/state.py", line 296, in render_multiple
    model.render(self)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/migrations/state.py", line 585, in render
    body,
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/models/base.py", line 158, in __new__
    new_class.add_to_class(obj_name, obj)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/models/base.py", line 299, in add_to_class
    value.contribute_to_class(cls, name)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/models/fields/related.py", line 707, in contribute_to_class
    super(ForeignObject, self).contribute_to_class(cls, name, virtual_only=virtual_only)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/models/fields/related.py", line 307, in contribute_to_class
    lazy_related_operation(resolve_related_class, cls, self.remote_field.model, field=self)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/models/fields/related.py", line 84, in lazy_related_operation
    return apps.lazy_model_operation(partial(function, **kwargs), *model_keys)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/models/fields/related.py", line 82, in <genexpr>
    model_keys = (make_model_tuple(m) for m in models)
  File "/Users/rooster/.virtualenvs/ddm_dev/lib/python3.5/site-packages/django/db/models/utils.py", line 13, in make_model_tuple
    app_label, model_name = model.split(".")
ValueError: too many values to unpack (expected 2)

Answer 1

如果使用Pycharm中的重构工具，意外地为整个项目而不是单个文件重命名模型的名称，则也会出现此问题。这也会影响迁移文件，因此，makemigrations命令不知道该怎么做，并抛出值错误。

我通过进入所有迁移文件并重命名这些行来修复它：

field=models.ForeignKey(default=1, null=True, on_delete=django.db.models.deletion.CASCADE, to='books.models.Topic'),

致：

field=models.ForeignKey(default=1, null=True, on_delete=django.db.models.deletion.CASCADE, to='books.Topic'),

Answer 2

只有当split()返回超过2个元素时，才会发生此错误：

app_label, model_name = model.split(".")
ValueError: too many values to unpack (expected 2)

这意味着app_label或model_name中都有一个点（.）。我的钱在前者，因为模型名是自动生成的

Answer 3

当您以错误的方式从另一个应用程序引用模型定义中的另一个模型时，也会发生这种情况。

检查此错误报告-https://code.djangoproject.com/ticket/24547

path should be of the form 'myapp.MyModel' and should NOT include the name of module containing models (which is usually 'models').

这个错误在状态工作表中，大部分不会被修复。