使用python从mongo gridfs下载文件

Question

我已将文件上传到mongo。但是，当我想在网络浏览器上通过httpresonse从mongo下载时，此操作无效。

这是views.py：

    if filename is not None:
    file_ = db.fs.files.find_one({
    'filename':filename
        })
    file_id = file_['_id']
    wrapper = fs.get(file_id).read()

    response =  StreamingHttpResponse(FileWrapper(wrapper),content_type=file_['contentType'])

    response['Content-Disposition'] = 'attachment; filename=%s' % str(filename)
    response['Content-Length']      = file_['length'] 
    return response

我收到此错误：

Traceback (most recent call last):
File "/usr/lib/python2.7/wsgiref/handlers.py", line 86, in run
self.finish_response()
File "/usr/lib/python2.7/wsgiref/handlers.py", line 126, in finish_response
for data in self.result:
File "/usr/local/lib/python2.7/dist-packages/django/utils/six.py", line 473, in next
return type(self).__next__(self)
 File "/usr/local/lib/python2.7/dist-packages/django/http/response.py", line 292, in   __next__
return self.make_bytes(next(self._iterator))
 File "/usr/lib/python2.7/wsgiref/util.py", line 30, in next
data = self.filelike.read(self.blksize)
AttributeError: 'str' object has no attribute 'read'

但是当我将StreamingHttpResponse更改为HttpResponse时，错误如下：

[30/Jul/2014 17:29:43] "GET /download/cs101/ HTTP/1.1" 200 664
/usr/lib/python2.7/wsgiref/handlers.py:126: DeprecationWarning: 
 Creating streaming     responses with `HttpResponse` is deprecated.
 Use `StreamingHttpResponse`instead if you need the streaming behavior.
for data in self.result:

Traceback (most recent call last):
 File "/usr/lib/python2.7/wsgiref/handlers.py", line 86, in run
   self.finish_response()
 File "/usr/lib/python2.7/wsgiref/handlers.py", line 126, in finish_response
for data in self.result:
 File "/usr/local/lib/python2.7/dist-packages/django/utils/six.py", line 473, in next
return type(self).__next__(self)
 File "/usr/local/lib/python2.7/dist-packages/django/http/response.py", line 292, in __next__
return self.make_bytes(next(self._iterator))
File "/usr/lib/python2.7/wsgiref/util.py", line 30, in next
data = self.filelike.read(self.blksize)
AttributeError: 'str' object has no attribute 'read'

提前致谢！

Answer 1

您在以下位置调用read方法：

wrapper = fs.get(file_id).read()

因此，您获得了str （假设Python 2，如果为3，则为bytes ）。 FileWrapper需要像对象这样的文件，而str当然不是一个。

尝试使用：

wrapper = fs.get(file_id)

这将返回类似于对象的文件。

OTOH，pymongo的.get()返回一个GridOut实例，该实例已经支持迭代 ，所以为什么不尝试以下方法：

wrapper = fs.get(file_id)
response =  StreamingHttpResponse(wrapper, content_type=file_['contentType'])