How to upload and read file in App Engine

Question

I have an upload html form:

<form method="post" enctype="multipart/form-data" action="{{ upload_url }}">
    <input type="file" id="import_groups_csv" name="import_groups_csv">
    <input type="submit" value="Import groups">
</form>

And this is the class that read the file from blobstore:

class UploadHandler(blobstore_handlers.BlobstoreUploadHandler):
    def post(self):
        upload_files = self.get_uploads('import_groups_csv')  # 'file' is file upload field in the form
        blob_info = upload_files[0]
        file = blobstore.get(blob_info.key()).open().read()
        for line in file:
            logging.info("line *******************"+str(line))
        self.redirect('/groups')

When the file is uploaded i want to read every line on it but with this i git already an Error and this is traceback:

INFO     2014-08-04 13:47:04,252 views.py:332] line *******************ERROR    2014-08-04 13:47:04,255 traceback.py:13] Traceback (most recent call last):

ERROR    2014-08-04 13:47:04,256 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\app_logging.py", line 78, in emit

ERROR    2014-08-04 13:47:04,256 traceback.py:13]     logservice.write(message)

ERROR    2014-08-04 13:47:04,256 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\logservice\logservice.py", line 347, in write

ERROR    2014-08-04 13:47:04,256 traceback.py:13]     logs_buffer().write(message)

ERROR    2014-08-04 13:47:04,256 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\logservice\logservice.py", line 236, in write

ERROR    2014-08-04 13:47:04,256 traceback.py:13]     return self._lock_and_call(self._write, line)

ERROR    2014-08-04 13:47:04,256 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\logservice\logservice.py", line 157, in _lock_and_call

ERROR    2014-08-04 13:47:04,256 traceback.py:13]     return method(*args)

ERROR    2014-08-04 13:47:04,256 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\logservice\logservice.py", line 253, in _write

ERROR    2014-08-04 13:47:04,256 traceback.py:13]     self._autoflush()

ERROR    2014-08-04 13:47:04,256 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\logservice\logservice.py", line 321, in _autoflush

ERROR    2014-08-04 13:47:04,256 traceback.py:13]     self._flush()

ERROR    2014-08-04 13:47:04,256 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\logservice\logservice.py", line 307, in _flush

ERROR    2014-08-04 13:47:04,256 traceback.py:13]     apiproxy_stub_map.MakeSyncCall('logservice', 'Flush', request, response)

ERROR    2014-08-04 13:47:04,256 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\apiproxy_stub_map.py", line 94, in MakeSyncCall

ERROR    2014-08-04 13:47:04,256 traceback.py:13]     return stubmap.MakeSyncCall(service, call, request, response)

ERROR    2014-08-04 13:47:04,257 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\apiproxy_stub_map.py", line 320, in MakeSyncCall

ERROR    2014-08-04 13:47:04,257 traceback.py:13]     rpc.CheckSuccess()

ERROR    2014-08-04 13:47:04,257 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\apiproxy_rpc.py", line 156, in _WaitImpl

ERROR    2014-08-04 13:47:04,257 traceback.py:13]     self.request, self.response)

ERROR    2014-08-04 13:47:04,257 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\apiproxy_stub.py", line 123, in MakeSyncCall

ERROR    2014-08-04 13:47:04,257 traceback.py:13]     method(request, response, request_id)

ERROR    2014-08-04 13:47:04,257 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\logservice\logservice_stub.py", line 182, in _Dynamic_Flush

ERROR    2014-08-04 13:47:04,257 traceback.py:13]     self._insert_app_logs(request_id, group.log_line_list())

ERROR    2014-08-04 13:47:04,257 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\apiproxy_stub.py", line 160, in WrappedMethod

ERROR    2014-08-04 13:47:04,259 traceback.py:13]     return method(self, *args, **kwargs)

ERROR    2014-08-04 13:47:04,259 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\logservice\logservice_stub.py", line 193, in _insert_app_logs

ERROR    2014-08-04 13:47:04,259 traceback.py:13]     '(?, ?, ?, ?)', new_app_logs)

ERROR    2014-08-04 13:47:04,259 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\logservice\logservice_stub.py", line 190, in <genexpr>

ERROR    2014-08-04 13:47:04,259 traceback.py:13]     for log_line in log_lines)

ERROR    2014-08-04 13:47:04,259 traceback.py:13]   File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\logservice\logservice_stub.py", line 200, in _tuple_from_log_line

ERROR    2014-08-04 13:47:04,259 traceback.py:13]     message = message.decode('utf-8')

ERROR    2014-08-04 13:47:04,259 traceback.py:13]   File "C:\Python27\lib\encodings\utf_8.py", line 16, in decode

ERROR    2014-08-04 13:47:04,259 traceback.py:13]     return codecs.utf_8_decode(input, errors, True)

ERROR    2014-08-04 13:47:04,259 traceback.py:13] UnicodeDecodeError: 'utf8' codec can't decode byte 0xff in position 27: invalid start byte

ERROR    2014-08-04 13:47:04,259 app_logging.py:82] Logged from file views.py, line 332

i have followed as specified in google developper for this, but it's poorly documented. any idea of the root cause ?

I take it that self.get_uploads actually writes the uploaded file to the blobstore? Can you log its blob_info.key() to make sure? Which is line 332 in views.py? If your template file save in UTF-8 format? — GAEfan
– GAEfan, Commented Aug 4, 2014 at 14:57
@GAEfan: i have log the str(blob_info.key()) gave me this : ifeaztEIMug6_bJzv9sNpw== and the line 332 in my views file is self.redirect('/groups') — Drwhite
– Drwhite, Commented Aug 4, 2014 at 15:22

GAEfan · Accepted Answer · 2014-08-04 15:29:29Z

1

Place this as the top line in your views.py:

# -*- coding: utf-8 -*-

And, make sure that views.py is saved in UTF-8 format. Depending in your text editor, go to Save As, and make sure it is Unicode, and not ASCII.

answered Aug 4, 2014 at 15:29

GAEfan

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