Python poster Content-Length error

Question

I was trying to send image with poster module. I followed the example, but it doesn't work for me

My code:

from poster.encode import multipart_encode
from poster.streaminghttp import register_openers
import urllib, urllib2

def decaptcha(hash):
register_openers()

    params = {
        "file": open("captcha.jpg", "rb"),
        "function" : "picture2",
        "username" : "uname",
        "password" : "pwd",
        "pict_to" : 0,
        "pict_type" : 0
        }


    datagen, headers = multipart_encode(params)

    req = urllib2.Request("http://poster.decaptcher.com/")

    solve = urllib2.urlopen(req, datagen, headers)
    print solve.read()

decaptcha(None)

And traceback:

`File "decaptcha.py", line 27, in <module>
    decaptcha(None)
  File "decaptcha.py", line 24, in decaptcha
    solve = urllib2.urlopen(req, datagen, headers)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py", line 126, in urlopen
    return _opener.open(url, data, timeout)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py", line 390, in open
    req = meth(req)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/poster-0.8.1-py2.7.egg/poster/streaminghttp.py", line 154, in http_request
    "No Content-Length specified for iterable body")
ValueError: No Content-Length specified for iterable body`

Answer 1

(Disclaimer: I have not used the poster library. The suggested solution is my best guess.)

From the poster docs, it looks as if this should work.

I would try the following (passes the file's contents instead of the open file iterator, should fix the iterable body issue):

params = {
    "file": open("captcha.jpg", "rb").read(),
    "function" : "picture2",
    "username" : "uname",
    "password" : "pwd",
    "pict_to" : 0,
    "pict_type" : 0
    }

Suggestion 2:

Or try: from multipart.encode import MultiPartParam

params = [
    MultiPartParam("file", fileobj=open("captcha.jpg", "rb")),
    ("function", picture2"),
    ("username", "uname"),
    ("password", "pwd"),
    ("pict_to", 0),
    ("pict_type", 0),
]

If this fails with the same error, try specifying the filesize parameter to MultiPartParam.

Answer 2

You should pass datagen and headers to Request, not urlopen:

req = urllib2.Request("http://poster.decaptcher.com/", datagen, headers)
solve = urllib2.urlopen(req)