如何通过实验性API将大文件写入Blobstore？

Question

我遇到了一些困扰……我正在使用tipfy框架同时将文件上传到scribd存储和blobstore。
我有一个网页表单，它的动作并不是通过blobstore.create_upload_url创建的（我只是用了url_for('myhandler')）。我这样做是因为如果使用blobstore处理程序，POST响应会被解析，这样我就无法使用正常的python-scribd API将文件上传到scribd存储。
现在我有一个可以正常工作的scribd保存器：

class UploadScribdHandler(RequestHandler, BlobstoreUploadMixin):
    def post(self):
        uploaded_file = self.request.files.get('upload_file')
        fname = uploaded_file.filename.strip()
        try:
            self.post_to_scribd(uploaded_file, fname)
        except Exception, e:
            # ... get the exception message and do something with it
            msg = e.message
            # ...
        # reset the stream to zero (beginning) so the file can be read again
        uploaded_file.seek(0)
        #removed try-except to see debug info in browser window
        # Create the file

        file_name = files.blobstore.create(_blobinfo_uploaded_filename=fname)
        # Open the file and write to it
        with files.open(file_name, 'a') as f:
            f.write(uploaded_file.read())
        # Finalize the file. Do this before attempting to read it.      
        files.finalize(file_name)
        # Get the file's blob key
        blob_key = files.blobstore.get_blob_key(file_name)

        return Response('done')

    def post_to_scribd(self, uploaded_file, fname):
        errmsg =''
        uploaded_file = self.request.files.get('upload_file')
        fname = uploaded_file.filename.strip()
        fext = fname[fname.rfind('.')+1:].lower()
        if (fext not in ALLOWED_EXTENSION):
            raise Exception('This file type does not allowed to be uploaded\n')
        if SCRIBD_ENABLED:
            doc_title = self.request.form.get('title')
            doc_description = self.request.form.get('description')
            doc_tags = self.request.form.get('tags')
            try:
                document = scribd.api_user.upload(uploaded_file, fname, access='private')
                #while document.get_conversion_status() != 'DONE':
                #   time.sleep(2)
                if not doc_title:
                    document.title = fname[:fname.rfind('.')]
                else:
                    document.title = doc_title
                if not doc_description:
                    document.description = 'This document was uploaded at ' + str(datetime.datetime.now()) +'\n'
                else:
                    document.description = doc_description
                document.tags = doc_tags
                document.save()
            except scribd.ResponseError, err:
                raise Exception('Scribd failed: error code:%d, error message: %s\n' % (err.errno, err.strerror))
            except scribd.NotReadyError, err:
                raise Exception('Scribd failed: error code:%d, error message: %s\n' % (err.errno, err.strerror))
            except:
                raise Exception('something wrong exception')

正如你所看到的，它也会将文件保存到blobstore中……但是如果我上传一个大文件（比如5Mb），我就会收到

RequestTooLargeError: The request to API call file.Append() was too large.
Request: docs.upload(access='private', doc_type='pdf', file=('PK\x03\x04\n\x00\x00\x00\x00\x00"\x01\x10=\x00\x00(...)', 'test.pdf'))

我该如何解决这个问题？
谢谢！

Answer 1

最后我找到了解决办法。

Nick Johneson 的回答出现了属性错误，因为 uploaded_file 被当作字符串处理了。

字符串是没有 read() 这个方法的。

因为字符串没有 read() 方法，所以我把文件字符串切割开，然后像他写的那样进行写入。

class UploadRankingHandler(webapp.RequestHandler):
  def post(self):
    fish_image_file = self.request.get('file')

    file_name = files.blobstore.create(mime_type='image/png', _blobinfo_uploaded_filename="testfilename.png")

    file_str_list = splitCount(fish_image_file,65520)

    with files.open(file_name, 'a') as f:
      for line in file_str_list:
        f.write(line)

你可以在这里查看关于 splitCount() 的内容。

http://www.bdhwan.com/entry/gaewritebigfile

Answer 2

你需要对文件API进行多次小的请求，比如这样：

with files.open(file_name, 'a') as f:
    data = uploaded_file.read(65536)
    while data:
      f.write(data)
      data = uploaded_file.read(65536)

请注意，普通请求到App Engine应用的负载大小限制是10MB；如果你想上传更大的文件，就需要使用常规的blobstore上传机制。