需要帮助处理Google App Engine Blobstore上传表单

Question

我正在学习blobstore API... 我已经能够成功上传文件并获取它们，但在尝试将上传表单和普通网页表单结合起来时遇到了困难，我想为文件关联一些额外的信息，比如文件的昵称。

下面是我正在玩的一款简单应用的代码。这个应用是基于谷歌提供的示例。

#!/usr/bin/env python
#

import os
import urllib

from google.appengine.ext import blobstore
from google.appengine.ext import webapp
from google.appengine.ext.webapp import blobstore_handlers
from google.appengine.ext.webapp import template
from google.appengine.ext.webapp.util import run_wsgi_app
from google.appengine.ext import db

class StoredFiles(db.Model):
    nickname = db.StringProperty()
    blobkey = blobstore.BlobReferenceProperty()

    @staticmethod
    def get_all():
        query = db.Query(StoredFiles)
        files = query.get()

        return files


def doRender(handler, page, templatevalues=None):
    path = os.path.join(os.path.dirname(__file__), page)
    handler.response.out.write(template.render(path, templatevalues))

class MainHandler(webapp.RequestHandler):
    def get(self):

        allfiles = StoredFiles.get_all()

        upload_url = blobstore.create_upload_url('/upload')

        templatevalues = {
                'allfiles': allfiles,
                'upload_url': upload_url,

            }
        doRender(self, 'index.html', templatevalues)

class UploadHandler(blobstore_handlers.BlobstoreUploadHandler):
    def post(self):
        upload_files = self.get_uploads('file')
        blob_info = upload_files[0]

        self.redirect('/save/%s' % blob_info.key())

class SaveHandler(webapp.RequestHandler):

    def get(self, resource):

        newFile = StoredFiles()
        newFile.nickname = self.request.get('nickname')
        resource = str(urllib.unquote(resource))
        newFile.blobkey = resource

        newFile.put()

        self.redirect('/')

class ServeHandler(blobstore_handlers.BlobstoreDownloadHandler):
    def get(self, resource):
        resource = str(urllib.unquote(resource))
        blob_info = blobstore.BlobInfo.get(resource)
        self.send_blob(blob_info)

def main():
    application = webapp.WSGIApplication(
          [('/', MainHandler),
           ('/upload', UploadHandler),
           ('/save/([^/]+)?', SaveHandler),
          ], debug=True)
    run_wsgi_app(application)

if __name__ == '__main__':
  main()

根据文档，blobstore处理程序应该把blob键和表单的其他内容传递给它重定向到的处理程序... blob键传递得很好，但其他内容却没有。

有人能告诉我我哪里出错了吗，或者推荐一个好的教程来描述这个用例吗？

Answer 1

问题在于，当你把请求重定向到"/save/%s"时，之前提交的表单数据就会丢失，这种情况是正常的。

与其重定向，不如把你的代码放在UploadHandler里面，像这样（这段代码没有测试过）：

class UploadHandler(blobstore_handlers.BlobstoreUploadHandler):
    def post(self):
        try:
            upload_files = self.get_uploads('file')
            blob_info = upload_files[0]

            newFile = StoredFiles()
            newFile.nickname = self.request.get('nickname')
            newFile.blobkey = blob_info.key()
            newFile.put()

            self.redirect('/')
        except:
            self.redirect('/upload_failure.html')

你可以查看文档中的这个页面，里面有类似的例子： http://code.google.com/appengine/docs/python/tools/webapp/blobstorehandlers.html#BlobstoreUploadHandler