django-cumulus:从django.db.models.ImageField检索PIL.Image对象

Question

我正在使用django-cumulus在Rackspace云上存储我的媒体。

我需要将数据从ImageField检索到PIL.Image。我需要它在这个图像上做一些改变(裁剪，滤镜等)。并将其保存到另一个积云ImageField。

我试过这段代码：

def field_to_image(field):
    # field - cumulus-powered ImageField on some model
    from StringIO import StringIO
    from PIL import Image
    r = field.read()  # ERROR throws here!
    image = Image.open(StringIO(r))
    return image

它在我一半的文件上运行良好，但在另一半文件上，我总是得到这样的错误：

Traceback (most recent call last):
File "tmp.py", line 78, in <module>
  resize_photos(start)
File "tmp.py", line 59, in resize_photos
  photo.make_thumbs()
File "/hosting/site/news/models.py", line 65, in make_thumbs
  i = functions.field_to_image(self.img)
File "/hosting/site/functions.py", line 169, in field_to_image
  r = field.read()
File "/usr/local/lib/python2.7/dist-packages/cumulus/storage.py", line 352, in read
  if self._pos == self._get_size() or chunk_size == 0:
File "/usr/local/lib/python2.7/dist-packages/cumulus/storage.py", line 322, in _get_size
  self._size = self._storage.size(self.name)
File "/usr/local/lib/python2.7/dist-packages/cumulus/storage.py", line 244, in size
  return self._get_object(name).total_bytes
AttributeError: 'bool' object has no attribute 'total_bytes'

有谁可以帮我？也许有更好的方法从rackspace中检索PIL.Image对象？

我正在尝试读取的文件()存在，并且可以通过Rackspace上的url获得

Answer 1

如果在容器中找不到该文件，则返回False，因此这是一个非常令人困惑的错误。它现在已经在repo中修复了，但在发布版本中仍然没有修复:它返回None而不是False：https://github.com/django-cumulus/django-cumulus/blob/master/cumulus/storage.py#L203

但问题的根本原因是:找不到文件。