Question

Ok,

This should be simple, since people do it all the time. I want to get the body of a POST request sent a twisted Agent. This is created with a twisted FileBodyProducer. On the server side, I get a request object for my render_POST method.

How do I retrieve the body?

server:

from twisted.web import server, resource
from twisted.internet import reactor


class Simple(resource.Resource):
    isLeaf = True
    def render_GET(self, request):
        return "{0}".format(request.args.keys())
    def render_POST(self, request):
        return "{0}".format(request.data)
        with open(request.args['filename'][0], 'rb') as fd:
            fd.write(request.write())

site = server.Site(Simple())
reactor.listenTCP(8080, site)
reactor.run()

client:

from StringIO import StringIO

from twisted.internet import reactor
from twisted.web.client import Agent
from twisted.web.http_headers import Headers

from twisted.web.client import FileBodyProducer
from twisted.internet.defer import Deferred
from twisted.internet.protocol import Protocol
from pprint import pformat

class BeginningPrinter(Protocol):
    def __init__(self, finished):
        self.finished = finished
        self.remaining = 1024 * 10

    def dataReceived(self, bytes):
        if self.remaining:
            display = bytes[:self.remaining]
            print 'Some data received:'
            print display
            self.remaining -= len(display)

    def connectionLost(self, reason):
        print 'Finished receiving body:', reason.getErrorMessage()
        self.finished.callback(None)

agent = Agent(reactor)
body = FileBodyProducer(StringIO("hello, world"))
d = agent.request(
    'POST',
    'http://127.0.0.1:8080/',
    Headers({'User-Agent': ['Twisted Web Client Example'],
             'Content-Type': ['text/x-greeting']}),
    body)

def cbRequest(response):
    print 'Response version:', response.version
    print 'Response code:', response.code
    print 'Response phrase:', response.phrase
    print 'Response headers:'
    print pformat(list(response.headers.getAllRawHeaders()))
    finished = Deferred()
    response.deliverBody(BeginningPrinter(finished))
    return finished
d.addCallback(cbRequest)

def cbShutdown(ignored):
    reactor.stop()
d.addBoth(cbShutdown)

reactor.run()

The only docs I can find for setting up the consumer side leave something to be desired. Primarily, how can a consumer use the write(data) method to receive results?

Which bit am I missing to plug these two components together?

Answer 1

All right, so it’s as simple as calling request.content.read(). This, as far as I can tell, is undocumented in the API.

Here’s the updated code for the client:

from twisted.internet import reactor
from twisted.web.client import Agent
from twisted.web.http_headers import Headers

from twisted.web.client import FileBodyProducer
from twisted.internet.defer import Deferred
from twisted.internet.protocol import Protocol
from pprint import pformat

class BeginningPrinter(Protocol):
    def __init__(self, finished):
        self.finished = finished
        self.remaining = 1024 * 10

    def dataReceived(self, bytes):
        if self.remaining:
            display = bytes[:self.remaining]
            print 'Some data received:'
            print display
            self.remaining -= len(display)

    def connectionLost(self, reason):
        print 'Finished receiving body:', reason.getErrorMessage()
        self.finished.callback(None)

class SaveContents(Protocol):
    def __init__(self, finished, filesize, filename):
        self.finished = finished
        self.remaining = filesize
        self.outfile = open(filename, 'wb')

    def dataReceived(self, bytes):
        if self.remaining:
            display = bytes[:self.remaining]
            self.outfile.write(display)
            self.remaining -= len(display)
        else:
            self.outfile.close()

    def connectionLost(self, reason):
        print 'Finished receiving body:', reason.getErrorMessage()
        self.outfile.close()
        self.finished.callback(None)

agent = Agent(reactor)
f = open('70935-new_barcode.pdf', 'rb')
body = FileBodyProducer(f)
d = agent.request(
    'POST',
    'http://127.0.0.1:8080?filename=test.pdf',
    Headers({'User-Agent': ['Twisted Web Client Example'],
             'Content-Type': ['multipart/form-data; boundary=1024'.format()]}),
    body)

def cbRequest(response):
    print 'Response version:', response.version
    print 'Response code:', response.code
    print 'Response phrase:', response.phrase
    print 'Response headers:'
    print 'Response length:', response.length
    print pformat(list(response.headers.getAllRawHeaders()))
    finished = Deferred()
    response.deliverBody(SaveContents(finished, response.length, 'test2.pdf'))
    return finished
d.addCallback(cbRequest)

def cbShutdown(ignored):
    reactor.stop()
d.addBoth(cbShutdown)

reactor.run()

And here’s the server:

from twisted.web import server, resource
from twisted.internet import reactor
import os

# multi part encoding example: http://marianoiglesias.com.ar/python/file-uploading-with-multi-part-encoding-using-twisted/
class Simple(resource.Resource):
    isLeaf = True
    def render_GET(self, request):
        return "{0}".format(request.args.keys())
    def render_POST(self, request):
        with open(request.args['filename'][0], 'wb') as fd:
            fd.write(request.content.read())
        request.setHeader('Content-Length', os.stat(request.args['filename'][0]).st_size)
        with open(request.args['filename'][0], 'rb') as fd:
            request.write(fd.read())
        request.finish()
        return server.NOT_DONE_YET

site = server.Site(Simple())
reactor.listenTCP(8080, site)
reactor.run()

I can now write the file contents I receive, and read back the results.