CODEWITHSUNDEEP
pythonflaskutf-8
Gresstant
Gresstant

Reputation: 35

Flask raises UnicodeEncodeError (latin-1) when send attachment with UTF-8 characters

I'm creating a file server by flask. When I'm testing the download feature, I found it raises UnicodeEncodeError if I try to download files named with UTF-8 characters.

Create a file at upload/1512026299/%E6%97%A0%E6%A0%87%E9%A2%98.png , then run codes below:

@app.route('/getfile/<timestamp>/<filename>')
def download(timestamp, filename):
    dirpath = os.path.join(os.path.join(os.path.abspath(os.path.dirname(__file__)), 'upload'), timestamp)
    return send_from_directory(dirpath, filename, as_attachment=True)

You will get an exception, which should be like this:

127.0.0.1 - - [30/Nov/2017 21:39:05] "GET /getfile/1512026299/%E6%97%A0%E6%A0%87%E9%A2%98.png HTTP/1.1" 200 -
Error on request:
Traceback (most recent call last):
  File "C:\Program Files\Python36\lib\site-packages\werkzeug\serving.py", line 209, in run_wsgi
    execute(self.server.app)
  File "C:\Program Files\Python36\lib\site-packages\werkzeug\serving.py", line 200, in execute
    write(data)
  File "C:\Program Files\Python36\lib\site-packages\werkzeug\serving.py", line 168, in write
    self.send_header(key, value)
  File "C:\Program Files\Python36\lib\http\server.py", line 508, in send_header
    ("%s: %s\r\n" % (keyword, value)).encode('latin-1', 'strict'))
UnicodeEncodeError: 'latin-1' codec can't encode characters in position 43-45: ordinal not in range(256)

Upvotes: 2

Views: 2926

Answers (1)

mata
mata

Reputation: 69022

The problem is that when using as_attachement=True the filename is sent in the headers. Unfortunately it seems that flask does not yet support rfc5987 which specifies how to encode attachment file names in a different encoding other than latin1.

The easiest solution in this case would be to drop as_attachement=True, then it won't be sent with a Content-Disposition header, which avoids this problem.

If you really have to send the Content-Disposition header you could try the code posted in the related issue:

    response = make_response(send_file(out_file))
    basename = os.path.basename(out_file)
    response.headers["Content-Disposition"] = \
        "attachment;" \
        "filename*=UTF-8''{utf_filename}".format(
            utf_filename=quote(basename.encode('utf-8'))
        )
    return response

This should be fixed in the next release (>0.12)

Upvotes: 7

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