Accessing POST Data from WSGI

Question

I can’t seem to figure out how to access POST data using WSGI. I tried the example on the wsgi.org website and it didn’t work. I’m using Python 3.0 right now. Please don’t recommend a WSGI framework as that is not what I’m looking for.

I would like to figure out how to get it into a fieldstorage object.

Asked By: Evan Fosmark

||

Source

Answer 1

I would suggest you look at how some frameworks do it for an example. (I am not recommending any single one, just using them as an example.)

Here is the code from Werkzeug:

http://dev.pocoo.org/projects/werkzeug/browser/werkzeug/wrappers.py#L150

which calls

http://dev.pocoo.org/projects/werkzeug/browser/werkzeug/utils.py#L1420

It’s a bit complicated to summarize here, so I won’t.

Answered By: Ali Afshar

Answer 2

body= ''  # b'' for consistency on Python 3.0
try:
    length= int(environ.get('CONTENT_LENGTH', '0'))
except ValueError:
    length= 0
if length!=0:
    body= environ['wsgi.input'].read(length)

Note that WSGI is not yet fully-specified for Python 3.0, and much of the popular WSGI infrastructure has not been converted (or has been 2to3d, but not properly tested). (Even wsgiref.simple_server won’t run.) You’re in for a rough time doing WSGI on 3.0 today.

Answered By: bobince

Answer 3

Assuming you are trying to get just the POST data into a FieldStorage object:

# env is the environment handed to you by the WSGI server.
# I am removing the query string from the env before passing it to the
# FieldStorage so we only have POST data in there.
post_env = env.copy()
post_env['QUERY_STRING'] = ''
post = cgi.FieldStorage(
    fp=env['wsgi.input'],
    environ=post_env,
    keep_blank_values=True
)

Answered By: Mike Boers

Answer 4

This worked for me (in Python 3.0):

import urllib.parse

post_input = urllib.parse.parse_qs(environ['wsgi.input'].readline().decode(),True)

Answered By: Jack

Answer 5

I had the same issue and I invested some time researching a solution.
the complete answer with details and ressources (since the one accepted here didnt work for me on python3, many errors to correct in env library etc):

# the code below is taken from and explained officially here:
# https://wsgi.readthedocs.io/en/latest/specifications/handling_post_forms.html
import cgi
def is_post_request(environ):
    if environ['REQUEST_METHOD'].upper() != 'POST':
        return False
    content_type = environ.get('CONTENT_TYPE', 'application/x-www-form-urlencoded')
    return (content_type.startswith('application/x-www-form-urlencoded' or content_type.startswith('multipart/form-data')))
def get_post_form(environ):
    assert is_post_request(environ)
    input = environ['wsgi.input']
    post_form = environ.get('wsgi.post_form')
    if (post_form is not None
        and post_form[0] is input):
        return post_form[2]
    # This must be done to avoid a bug in cgi.FieldStorage
    environ.setdefault('QUERY_STRING', '')
    fs = cgi.FieldStorage(fp=input,
                          environ=environ,
                          keep_blank_values=1)
    new_input = InputProcessed()
    post_form = (new_input, input, fs)
    environ['wsgi.post_form'] = post_form
    environ['wsgi.input'] = new_input
    return fs
class InputProcessed(object):
    def read(self, *args):
        raise EOFError('The wsgi.input stream has already been consumed')
    readline = readlines = __iter__ = read

# the basic and expected application function for wsgi
# get_post_form(environ) returns a FieldStorage object
# to access the values use the method .getvalue('the_key_name')
# this is explained officially here:
# https://docs.python.org/3/library/cgi.html
# if you don't know what are the keys, use .keys() method and loop through them
def application(environ, start_response):
    start_response('200 OK', [('Content-type', 'text/plain')])
    user = get_post_form(environ).getvalue('user')
    password = get_post_form(environ).getvalue('password')
    output = 'user is: '+user+' and password is: '+password
    return [output.encode()]

Answered By: user16510763

Accessing POST Data from WSGI

Question:

Answers: