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

Question

我使用django-cumulus将我的媒体存储在Rackspace云中。

我需要从ImageField检索数据到PIL.Image。我需要它对这个图像进行一些修改（裁剪，过滤器等），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 

它的工作对我的档案一半好，但对另一半我总是收到此错误：

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' 

谁能帮助我？也许有更好的方法从rackspace检索PIL.Image对象？

的文件，我想读（）存在并且可透过网址上Rackspace公司

Answer 1

如果文件没有在容器中找到它返回False，因此是一个非常令人困惑的错误。 它在回购现在是固定的，但仍然无法在发布的版本：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：该文件未找到。