Django运行时错误：超出最大递归深度

Question

我刚接触Django。为了在我的Mac上安装Django，我用了easy_install，并且在Eclipse里安装了PyDev的Django插件。我按照标准步骤创建了一个新的PyDev Django项目。但是当我尝试以PyDev: Django的方式运行这个项目时，出现了以下错误。

Validating models...

RuntimeError: maximum recursion depth exceeded

我还试着在manage.py文件里添加了以下一行，但没有任何用处。

sys.setrecursionlimit(2000)

这是部分的错误追踪信息。

Unhandled exception in thread started by <bound method Command.inner_run of    <django.contrib.staticfiles.management.commands.runserver.Command object at 0x10e2*****>>
Traceback (most recent call last):
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/core/management/commands/runserver.py", line 92, in inner_run
self.validate(display_num_errors=True)
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/core/management/base.py", line 280, in validate
num_errors = get_validation_errors(s, app)
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/core/management/validation.py", line 35, in get_validation_errors
for (app_name, error) in get_app_errors().items():
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/db/models/loading.py", line 166, in get_app_errors
self._populate()
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/db/models/loading.py", line 72, in _populate
self.load_app(app_name, True)
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/db/models/loading.py", line 96, in load_app
models = import_module('.models', app_name)
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/utils/importlib.py", line 35, in import_module
__import__(name)
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/contrib/auth/models.py", line 370, in <module>
class AbstractUser(AbstractBaseUser, PermissionsMixin):
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/db/models/base.py", line 213, in __new__
new_class.add_to_class(field.name, copy.deepcopy(field))
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/db/models/base.py", line 265, in add_to_class
value.contribute_to_class(cls, name)
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/db/models/fields/__init__.py", line 257, in contribute_to_class
cls._meta.add_field(self)
File "/Library/Python/2.7/site-packages/Django-1.5-py2.7.egg/django/db/models/options.py", line 179, in add_field
self.local_fields.insert(bisect(self.local_fields, field), field)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/functools.py", line 56, in <lambda>
'__lt__': [('__gt__', lambda self, other: other < self),
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/functools.py", line 56, in <lambda>
'__lt__': [('__gt__', lambda self, other: other < self),
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/functools.py", line 56, in <lambda>
'__lt__': [('__gt__', lambda self, other: other < self),
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/functools.py", line 56, in <lambda>
'__lt__': [('__gt__', lambda self, other: other < self),

我到底哪里做错了呢？

Answer 1

我在使用 pyenv virtualenvs 和 Python 2.7.1 的时候遇到过几次这个问题。我不想去修改核心文件，所以我把版本升级到了 2.7.5，结果一切都正常了。希望这个方法对你们中的一些人有帮助。

Answer 2

我把PyDev、Django和Python都卸载了，然后重新安装了一遍，现在一切正常了。谢谢大家！

Answer 3

问题出在functools.py这个文件里。这个文件是Python的一部分。

要解决这个问题，需要把这个（大约在python\Lib\functools.py的第56行）:

    convert = {
    '__lt__': [('__gt__', lambda self, other: other < self),
               ('__le__', lambda self, other: not other < self),
               ('__ge__', lambda self, other: not self < other)],
    '__le__': [('__ge__', lambda self, other: other <= self),
               ('__lt__', lambda self, other: not other <= self),
               ('__gt__', lambda self, other: not self <= other)],
    '__gt__': [('__lt__', lambda self, other: other > self),
               ('__ge__', lambda self, other: not other > self),
               ('__le__', lambda self, other: not self > other)],
    '__ge__': [('__le__', lambda self, other: other >= self),
               ('__gt__', lambda self, other: not other >= self),
               ('__lt__', lambda self, other: not self >= other)]
}

替换成这个:

    convert = {
    '__lt__': [('__gt__', lambda self, other: not (self < other or self == other)),
               ('__le__', lambda self, other: self < other or self == other),
               ('__ge__', lambda self, other: not self < other)],
    '__le__': [('__ge__', lambda self, other: not self <= other or self == other),
               ('__lt__', lambda self, other: self <= other and not self == other),
               ('__gt__', lambda self, other: not self <= other)],
    '__gt__': [('__lt__', lambda self, other: not (self > other or self == other)),
               ('__ge__', lambda self, other: self > other or self == other),
               ('__le__', lambda self, other: not self > other)],
    '__ge__': [('__le__', lambda self, other: (not self >= other) or self == other),
               ('__gt__', lambda self, other: self >= other and not self == other),
               ('__lt__', lambda self, other: not self >= other)]
}

另外，您可以阅读这个链接了解更多信息： http://regebro.wordpress.com/2010/12/13/python-implementing-rich-comparison-the-correct-way/