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pythonftpibm-midrangeflask-socketio

Python FTP get file from as400

I have a simple code (using Flask-SocketIO and ftplib) for downloading csv file from as400 machine, but I got an exception which I do not understand...

Do you know what the problem is?

The code I have:

try:
    localFile = open(localDir + '/' + iso + '/' + output, 'w')
except:
    emit('update-status', (iso, 'Error: Couldn\'t create file ' + localDir + '/' + iso + '/' + output + ' !'))
    return

print('RETR ' + as400Dir + '/' + output)
try:
    ftp.retrlines('RETR ' + as400Dir + '/' + output, localFile.write)
except ftplib.all_errors as e:
# except Exception as e:
    emit('update-status', (iso, 'Error: Couldn\'t download file ' + as400Dir + "/" + output + ' ! -> ' + str(e)))
    return

localFile.close()

Console output:

RETR /xreff/pgmref.csv
Exception in thread Thread-5:
Traceback (most recent call last):
  File "D:\LocalData\xxx\Install\Python35-32\lib\threading.py", line 914, in _bootstrap_inner
    self.run()
  File "D:\LocalData\xxx\Install\Python35-32\lib\threading.py", line 862, in run
    self._target(*self._args, **self._kwargs)
  File "D:\LocalData\xxx\Install\Python35-32\lib\site-packages\socketio\server.py", line 452, in _handle_event_internal
    r = server._trigger_event(data[0], namespace, sid, *data[1:])
  File "D:\LocalData\xxx\Install\Python35-32\lib\site-packages\socketio\server.py", line 481, in _trigger_event
    return self.handlers[namespace][event](*args)
  File "D:\LocalData\xxx\Install\Python35-32\lib\site-packages\flask_socketio\__init__.py", line 236, in _handler
    *args)
  File "D:\LocalData\xxx\Install\Python35-32\lib\site-packages\flask_socketio\__init__.py", line 618, in _handle_event
    ret = handler(*args)
  File "./index.py", line 453, in updateDatabase
    downloadResourceFiles(iso, user, password, xreff, gafint, sugar)
  File "./index.py", line 545, in downloadResourceFiles
    downloadFiles()
  File "./index.py", line 523, in downloadFiles
    ftp.retrlines('RETR ' + as400Dir + '/' + output, localFile.write)
  File "D:\LocalData\xxx\Install\Python35-32\lib\ftplib.py", line 467, in retrlines
    with self.transfercmd(cmd) as conn, \
AttributeError: __exit__

And if I try except Exception as e instead of except ftplib.all_errors as e I get:

RETR /xreff/pgmref.csv
emitting event "update-status" to b563563a763e48fbba2d394ae8c871e7 [/]
b563563a763e48fbba2d394ae8c871e7: Sending packet MESSAGE data 2["update-status","NL","Error: Couldn't download file /xreff/pgmref.csv ! -> __exit__"]
Solution

  • I was able to reproduce your problem. This seems to be a bug in eventlet. You did not say if you are using eventlet in combination with Flask-SocketIO, but given that this is what the docs recommend I assume you were.

    Here is a simple eventlet script that fails in the same way as ftplib does:

    import eventlet
eventlet.monkey_patch()

import socket

with socket.create_connection(('google.com', 80)) as s:
    pass

    Output of running this script:

    $ python test.py
Traceback (most recent call last):
  File "test.py", line 6, in <module>
    with socket.create_connection(('google.com', 80)) as s:
AttributeError: __enter__

    The problem is that eventlet's socket class does not have the __exit__ method that enables it to be used as a context manager. I reported an issue to the eventlet project: https://github.com/eventlet/eventlet/issues/430

    Note that this error only occurs in Python 3. The context manager support for socket.create_connection() does not exist in Python 2, so in that version the ftplib implementation of retrlines() is done in a different way.