ValueError：在 Django 中解压的值太多（预期为 2）

Question

我正在重组我的一个项目，使其更易于重用，并且通常结构更好，现在每当我运行时都会收到以下错误 makemigrations - 我花了半天时间试图在我的拥有但已用完 Google 搜索结果，我需要一些帮助。我所做的是删除我设置的自定义用户模型，这样我就可以使用 Django 的内置用户模型，并且我还命名了我的应用程序 url。我不想包含一堆代码，它们只会弄脏这篇文章，因为我希望 Traceback 有我没有看到的线索。如果您正在看这个并且知道什么可能是错误的罪魁祸首，您能否就您需要看到的内容提供建议以提供帮助？谢谢你。

     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)

原文由 Charles Smith 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

仅当 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 中有一个点 ( . )。我的钱花在了前者身上，因为模型名称是自动生成的

原文由 Selcuk 发布，翻译遵循 CC BY-SA 3.0 许可协议

Answer 2

如果您在 Pycharm 中使用重构工具并意外地为整个项目而不是单个文件重命名模型的名称，也会出现此问题。这也会影响迁移文件，因此 makemigrations 命令不知道该做什么并抛出 Value 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'),

至：

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

原文由 Artur 发布，翻译遵循 CC BY-SA 3.0 许可协议