Question

我创建了一个Django File对象的子类来处理远程文件。我还想通过创建一个子类化Lazyobject类的RemoteFileLazy来创建一个懒惰的版本，但它不能像我预期的那样工作。我收到了错误。

import urllib2
from django.core.files.base import File
from django.utils.functional import LazyObject

class RemoteFile(File):

    def __init__(self, url):
        super(RemoteFile, self).__init__(urllib2.urlopen(urllib2.Request(url)))

    def __str__(self):
        return 'Remote content'

    def __nonzero__(self):
        return True

    def open(self, mode=None):
        self.seek(0)

    def close(self):
        pass

    def chunks(self, chunk_size=None):
    # CHUNKS taking care of no known size!
        if not chunk_size:
            chunk_size = self.DEFAULT_CHUNK_SIZE

        if hasattr(self, 'seek'):
            self.seek(0)
        # Assume the pointer is at zero...
        counter = self.size

        while True:
            data = self.read(chunk_size)
            if not data:
                break
            yield data

class RemoteFileLazy(LazyObject):

    def __init__(self, url):
        # # as said in the django code: For some reason, we have to inline LazyObject.__init__ here to avoid
        # recursion
        self._wrapped = None
        self.url = url

    def _setup(self):
        self._wrapped = RemoteFile(self.url)

当我运行此代码时：

rfl = filehelper.RemoteFileLazy(url="http://www.google.fr")

我收到了这个错误：

RuntimeError: maximum recursion depth exceeded

有什么想法吗？我没有调用LazyObject。 init ，因为它在django代码中提到了虽然...... 我认为 init 方法中的“self.url = url”会触发此错误吗？所以我不能使用带属性的惰性对象？

感谢。

回溯：

c:\Users\Michael\Dropbox\development\tools\Portable Python 2.7.2.1-django1.3.1\App\lib\site-packages\django\utils\functional.pyc in __getattr__(self, name)
    274     def __getattr__(self, name):
    275         if self._wrapped is None:
--> 276             self._setup()
    277         return getattr(self._wrapped, name)
    278

C:\Users\Michael\Dropbox\development\projects\django-socialdealing\socialdealing\apps\etl\utils\filehelper.py in _setup(self)
     58
     59     def _setup(self):
---> 60         self._wrapped = RemoteFile(self.url)
     61
     62

c:\Users\Michael\Dropbox\development\tools\Portable Python 2.7.2.1-django1.3.1\App\lib\site-packages\django\utils\functional.pyc in __getattr__(self, name)
    274     def __getattr__(self, name):
    275         if self._wrapped is None:
--> 276             self._setup()
    277         return getattr(self._wrapped, name)
    278

Answer 1

您不能以正常方式在LazyObject包装器上分配属性，它应该被视为包装对象，因此尝试将访问传递给尚未创建的包装对象您指定给url的点。

要修复它，请替换

self.url = url # this tries to retrieve the wrapped object to set its 'url' attribute

与

self.__dict__['url'] = url # this actually stores an attribute on the LazyObject container.

顺便说一下，当'借用'这样的django内部时，你会想要每次升级django时都非常难以测试。

RuntimeError：超出最大递归深度：为什么？

1 个答案: