Can I upload an object in memory to FTP using Python?

Question

Here's what I'm doing now:

mysock = urllib.urlopen('http://localhost/image.jpg')
fileToSave = mysock.read()
oFile = open(r"C:\image.jpg",'wb')
oFile.write(fileToSave)
oFile.close
f=file('image.jpg','rb')
ftp.storbinary('STOR '+os.path.basename('image.jpg'),f)
os.remove('image.jpg')

Writing files to disk and then imediately deleting them seems like extra work on the system that should be avoided. Can I upload an object in memory to FTP using Python?

Answer 1

Because of duck-typing, the file object (f in your code) only needs to support the .read(blocksize) call to work with storbinary. When faced with questions like this, I go to the source, in this case lib/python2.6/ftplib.py:

def storbinary(self, cmd, fp, blocksize=8192, callback=None):
    """Store a file in binary mode.  A new port is created for you.

    Args:
      cmd: A STOR command.
      fp: A file-like object with a read(num_bytes) method.
      blocksize: The maximum data size to read from fp and send over
                 the connection at once.  [default: 8192]
      callback: An optional single parameter callable that is called on
                on each block of data after it is sent.  [default: None]

    Returns:
      The response code.
    """
    self.voidcmd('TYPE I')
    conn = self.transfercmd(cmd)
    while 1:
        buf = fp.read(blocksize)
        if not buf: break
        conn.sendall(buf)
        if callback: callback(buf)
    conn.close()
    return self.voidresp()

As commented, it only wants a file-like object, indeed it not even be particularly file-like, it just needs read(n). StringIO provides such "memory file" services.