'''
UrlRequest
==========
.. versionadded:: 1.0.8
You can use the :class:`UrlRequest` to make asynchronous requests on the
web and get the result when the request is completed. The spirit is the
same as the XHR object in Javascript.
The content is also decoded if the Content-Type is
application/json and the result automatically passed through json.loads.
The syntax to create a request::
from kivy.network.urlrequest import UrlRequest
req = UrlRequest(url, on_success, on_redirect, on_failure, on_error,
on_progress, req_body, req_headers, chunk_size,
timeout, method, decode, debug, file_path, ca_file,
verify)
Only the first argument is mandatory: the rest are optional.
By default, a "GET" request will be sent. If the :attr:`UrlRequest.req_body` is
not None, a "POST" request will be sent. It's up to you to adjust
:attr:`UrlRequest.req_headers` to suit your requirements and the response
to the request will be accessible as the parameter called "result" on
the callback function of the on_success event.
Example of fetching JSON::
def got_json(req, result):
for key, value in result['headers'].items():
print('{}: {}'.format(key, value))
req = UrlRequest('https://httpbin.org/headers', got_json)
Example of Posting data (adapted from httplib example)::
import urllib
def bug_posted(req, result):
print('Our bug is posted!')
print(result)
params = urllib.urlencode({'@number': 12524, '@type': 'issue',
'@action': 'show'})
headers = {'Content-type': 'application/x-www-form-urlencoded',
'Accept': 'text/plain'}
req = UrlRequest('bugs.python.org', on_success=bug_posted, req_body=params,
req_headers=headers)
If you want a synchronous request, you can call the wait() method.
'''
from base64 import b64encode
from collections import deque
from threading import Thread, Event
from json import loads
from time import sleep
from kivy.compat import PY2
from kivy.config import Config
if PY2:
from httplib import HTTPConnection
from urlparse import urlparse, urlunparse
else:
from http.client import HTTPConnection
from urllib.parse import urlparse, urlunparse
try:
import ssl
HTTPSConnection = None
if PY2:
from httplib import HTTPSConnection
else:
from http.client import HTTPSConnection
except ImportError:
# depending the platform, if openssl support wasn't compiled before python,
# this class is not available.
pass
from kivy.clock import Clock
from kivy.weakmethod import WeakMethod
from kivy.logger import Logger
# list to save UrlRequest and prevent GC on un-referenced objects
g_requests = []
[docs]class UrlRequest(Thread):
'''A UrlRequest. See module documentation for usage.
.. versionchanged:: 1.5.1
Add `debug` parameter
.. versionchanged:: 1.0.10
Add `method` parameter
.. versionchanged:: 1.8.0
Parameter `decode` added.
Parameter `file_path` added.
Parameter `on_redirect` added.
Parameter `on_failure` added.
.. versionchanged:: 1.9.1
Parameter `ca_file` added.
Parameter `verify` added.
.. versionchanged:: 1.10.0
Parameters `proxy_host`, `proxy_port` and `proxy_headers` added.
.. versionchanged:: 1.11.0
Parameters `on_cancel` added.
:Parameters:
`url`: str
Complete url string to call.
`on_success`: callback(request, result)
Callback function to call when the result has been fetched.
`on_redirect`: callback(request, result)
Callback function to call if the server returns a Redirect.
`on_failure`: callback(request, result)
Callback function to call if the server returns a Client or
Server Error.
`on_error`: callback(request, error)
Callback function to call if an error occurs.
`on_progress`: callback(request, current_size, total_size)
Callback function that will be called to report progression of the
download. `total_size` might be -1 if no Content-Length has been
reported in the http response.
This callback will be called after each `chunk_size` is read.
`on_cancel`: callback(request)
Callback function to call if user requested to cancel the download
operation via the .cancel() method.
`req_body`: str, defaults to None
Data to sent in the request. If it's not None, a POST will be done
instead of a GET.
`req_headers`: dict, defaults to None
Custom headers to add to the request.
`chunk_size`: int, defaults to 8192
Size of each chunk to read, used only when `on_progress` callback
has been set. If you decrease it too much, a lot of on_progress
callbacks will be fired and will slow down your download. If you
want to have the maximum download speed, increase the chunk_size
or don't use ``on_progress``.
`timeout`: int, defaults to None
If set, blocking operations will timeout after this many seconds.
`method`: str, defaults to 'GET' (or 'POST' if ``body`` is specified)
The HTTP method to use.
`decode`: bool, defaults to True
If False, skip decoding of the response.
`debug`: bool, defaults to False
If True, it will use the Logger.debug to print information
about url access/progression/errors.
`file_path`: str, defaults to None
If set, the result of the UrlRequest will be written to this path
instead of in memory.
`ca_file`: str, defaults to None
Indicates a SSL CA certificate file path to validate HTTPS
certificates against
`verify`: bool, defaults to True
If False, disables SSL CA certificate verification
`proxy_host`: str, defaults to None
If set, the proxy host to use for this connection.
`proxy_port`: int, defaults to None
If set, and `proxy_host` is also set, the port to use for
connecting to the proxy server.
`proxy_headers`: dict, defaults to None
If set, and `proxy_host` is also set, the headers to send to the
proxy server in the ``CONNECT`` request.
'''
def __init__(self, url, on_success=None, on_redirect=None,
on_failure=None, on_error=None, on_progress=None,
req_body=None, req_headers=None, chunk_size=8192,
timeout=None, method=None, decode=True, debug=False,
file_path=None, ca_file=None, verify=True, proxy_host=None,
proxy_port=None, proxy_headers=None, user_agent=None,
on_cancel=None):
super(UrlRequest, self).__init__()
self._queue = deque()
self._trigger_result = Clock.create_trigger(self._dispatch_result, 0)
self.daemon = True
self.on_success = WeakMethod(on_success) if on_success else None
self.on_redirect = WeakMethod(on_redirect) if on_redirect else None
self.on_failure = WeakMethod(on_failure) if on_failure else None
self.on_error = WeakMethod(on_error) if on_error else None
self.on_progress = WeakMethod(on_progress) if on_progress else None
self.on_cancel = WeakMethod(on_cancel) if on_cancel else None
self.decode = decode
self.file_path = file_path
self._debug = debug
self._result = None
self._error = None
self._is_finished = False
self._resp_status = None
self._resp_headers = None
self._resp_length = -1
self._chunk_size = chunk_size
self._timeout = timeout
self._method = method
self.ca_file = ca_file
self.verify = verify
self._proxy_host = proxy_host
self._proxy_port = proxy_port
self._proxy_headers = proxy_headers
self._cancel_event = Event()
#: Url of the request
self.url = url
#: Request body passed in __init__
self.req_body = req_body
#: Request headers passed in __init__
self.req_headers = req_headers
# save our request to prevent GC
g_requests.append(self)
self.start()
[docs] def run(self):
q = self._queue.appendleft
url = self.url
req_body = self.req_body
req_headers = self.req_headers or {}
if (
Config.has_section('network')
and 'useragent' in Config.items('network')
):
useragent = Config.get('network', 'useragent')
req_headers.setdefault('User-Agent', useragent)
try:
result, resp = self._fetch_url(url, req_body, req_headers, q)
if self.decode:
result = self.decode_result(result, resp)
except Exception as e:
q(('error', None, e))
else:
if not self._cancel_event.is_set():
q(('success', resp, result))
else:
q(('killed', None, None))
# using trigger can result in a missed on_success event
self._trigger_result()
# clean ourself when the queue is empty
while len(self._queue):
sleep(.1)
self._trigger_result()
# ok, authorize the GC to clean us.
if self in g_requests:
g_requests.remove(self)
def _parse_url(self, url):
parse = urlparse(url)
host = parse.hostname
port = parse.port
userpass = None
# append user + pass to hostname if specified
if parse.username and parse.password:
userpass = {
"Authorization": "Basic {}".format(b64encode(
"{}:{}".format(
parse.username,
parse.password
).encode('utf-8')
).decode('utf-8'))
}
return host, port, userpass, parse
def _fetch_url(self, url, body, headers, q):
# Parse and fetch the current url
trigger = self._trigger_result
chunk_size = self._chunk_size
report_progress = self.on_progress is not None
timeout = self._timeout
file_path = self.file_path
ca_file = self.ca_file
verify = self.verify
if self._debug:
Logger.debug('UrlRequest: {0} Fetch url <{1}>'.format(
id(self), url))
Logger.debug('UrlRequest: {0} - body: {1}'.format(
id(self), body))
Logger.debug('UrlRequest: {0} - headers: {1}'.format(
id(self), headers))
# parse url
host, port, userpass, parse = self._parse_url(url)
if userpass and not headers:
headers = userpass
elif userpass and headers:
key = list(userpass.keys())[0]
headers[key] = userpass[key]
# translate scheme to connection class
cls = self.get_connection_for_scheme(parse.scheme)
# reconstruct path to pass on the request
path = parse.path
if parse.params:
path += ';' + parse.params
if parse.query:
path += '?' + parse.query
if parse.fragment:
path += '#' + parse.fragment
# create connection instance
args = {}
if timeout is not None:
args['timeout'] = timeout
if ca_file is not None and hasattr(ssl, 'create_default_context'):
ctx = ssl.create_default_context(cafile=ca_file)
ctx.verify_mode = ssl.CERT_REQUIRED
args['context'] = ctx
if not verify and parse.scheme == 'https' and (
hasattr(ssl, 'create_default_context')):
ctx = ssl.create_default_context()
ctx.check_hostname = False
ctx.verify_mode = ssl.CERT_NONE
args['context'] = ctx
if self._proxy_host:
Logger.debug('UrlRequest: {0} - proxy via {1}:{2}'.format(
id(self), self._proxy_host, self._proxy_port
))
req = cls(self._proxy_host, self._proxy_port, **args)
if parse.scheme == 'https':
req.set_tunnel(host, port, self._proxy_headers)
else:
path = urlunparse(parse)
else:
req = cls(host, port, **args)
# send request
method = self._method
if method is None:
method = 'GET' if body is None else 'POST'
req.request(method, path, body, headers or {})
# read header
resp = req.getresponse()
# read content
if report_progress or file_path is not None:
try:
total_size = int(resp.getheader('content-length'))
except:
total_size = -1
# before starting the download, send a fake progress to permit the
# user to initialize his ui
if report_progress:
q(('progress', resp, (0, total_size)))
def get_chunks(fd=None):
bytes_so_far = 0
result = b''
while 1:
chunk = resp.read(chunk_size)
if not chunk:
break
if fd:
fd.write(chunk)
else:
result += chunk
bytes_so_far += len(chunk)
# report progress to user
if report_progress:
q(('progress', resp, (bytes_so_far, total_size)))
trigger()
if self._cancel_event.is_set():
break
return bytes_so_far, result
if file_path is not None:
with open(file_path, 'wb') as fd:
bytes_so_far, result = get_chunks(fd)
else:
bytes_so_far, result = get_chunks()
# ensure that results are dispatched for the last chunk,
# avoid trigger
if report_progress:
q(('progress', resp, (bytes_so_far, total_size)))
trigger()
else:
result = resp.read()
try:
if isinstance(result, bytes):
result = result.decode('utf-8')
except UnicodeDecodeError:
# if it's an image? decoding would not work
pass
req.close()
# return everything
return result, resp
[docs] def get_connection_for_scheme(self, scheme):
'''Return the Connection class for a particular scheme.
This is an internal function that can be expanded to support custom
schemes.
Actual supported schemes: http, https.
'''
if scheme == 'http':
return HTTPConnection
elif scheme == 'https' and HTTPSConnection is not None:
return HTTPSConnection
else:
raise Exception('No class for scheme %s' % scheme)
[docs] def decode_result(self, result, resp):
'''Decode the result fetched from url according to his Content-Type.
Currently supports only application/json.
'''
# Entry to decode url from the content type.
# For example, if the content type is a json, it will be automatically
# decoded.
content_type = resp.getheader('Content-Type', None)
if content_type is not None:
ct = content_type.split(';')[0]
if ct == 'application/json':
if isinstance(result, bytes):
result = result.decode('utf-8')
try:
return loads(result)
except:
return result
return result
def _dispatch_result(self, dt):
while True:
# Read the result pushed on the queue, and dispatch to the client
try:
result, resp, data = self._queue.pop()
except IndexError:
return
if resp:
# Small workaround in order to prevent the situation mentioned
# in the comment below
final_cookies = ""
parsed_headers = []
for key, value in resp.getheaders():
if key == "Set-Cookie":
final_cookies += "{};".format(value)
else:
parsed_headers.append((key, value))
parsed_headers.append(("Set-Cookie", final_cookies[:-1]))
# XXX usage of dict can be dangerous if multiple headers
# are set even if it's invalid. But it look like it's ok
# ? http://stackoverflow.com/questions/2454494/..
# ..urllib2-multiple-set-cookie-headers-in-response
self._resp_headers = dict(parsed_headers)
self._resp_status = resp.status
if result == 'success':
status_class = resp.status // 100
if status_class in (1, 2):
if self._debug:
Logger.debug('UrlRequest: {0} Download finished with'
' {1} datalen'.format(id(self),
len(data)))
self._is_finished = True
self._result = data
if self.on_success:
func = self.on_success()
if func:
func(self, data)
elif status_class == 3:
if self._debug:
Logger.debug('UrlRequest: {} Download '
'redirected'.format(id(self)))
self._is_finished = True
self._result = data
if self.on_redirect:
func = self.on_redirect()
if func:
func(self, data)
elif status_class in (4, 5):
if self._debug:
Logger.debug('UrlRequest: {} Download failed with '
'http error {}'.format(id(self),
resp.status))
self._is_finished = True
self._result = data
if self.on_failure:
func = self.on_failure()
if func:
func(self, data)
elif result == 'error':
if self._debug:
Logger.debug('UrlRequest: {0} Download error '
'<{1}>'.format(id(self), data))
self._is_finished = True
self._error = data
if self.on_error:
func = self.on_error()
if func:
func(self, data)
elif result == 'progress':
if self._debug:
Logger.debug('UrlRequest: {0} Download progress '
'{1}'.format(id(self), data))
if self.on_progress:
func = self.on_progress()
if func:
func(self, data[0], data[1])
elif result == 'killed':
if self._debug:
Logger.debug('UrlRequest: Cancelled by user')
if self.on_cancel:
func = self.on_cancel()
if func:
func(self)
else:
assert(0)
@property
def is_finished(self):
'''Return True if the request has finished, whether it's a
success or a failure.
'''
return self._is_finished
@property
def result(self):
'''Return the result of the request.
This value is not determined until the request is finished.
'''
return self._result
@property
def resp_headers(self):
'''If the request has been completed, return a dictionary containing
the headers of the response. Otherwise, it will return None.
'''
return self._resp_headers
@property
def resp_status(self):
'''Return the status code of the response if the request is complete,
otherwise return None.
'''
return self._resp_status
@property
def error(self):
'''Return the error of the request.
This value is not determined until the request is completed.
'''
return self._error
@property
def chunk_size(self):
'''Return the size of a chunk, used only in "progress" mode (when
on_progress callback is set.)
'''
return self._chunk_size
[docs] def wait(self, delay=0.5):
'''Wait for the request to finish (until :attr:`resp_status` is not
None)
.. note::
This method is intended to be used in the main thread, and the
callback will be dispatched from the same thread
from which you're calling.
.. versionadded:: 1.1.0
'''
while self.resp_status is None:
self._dispatch_result(delay)
sleep(delay)
[docs] def cancel(self):
'''Cancel the current request. It will be aborted, and the result
will not be dispatched. Once cancelled, the callback on_cancel will
be called.
.. versionadded:: 1.11.0
'''
self._cancel_event.set()
if __name__ == '__main__':
from pprint import pprint
def on_success(req, result):
pprint('Got the result:')
pprint(result)
def on_error(req, error):
pprint('Got an error:')
pprint(error)
req = UrlRequest('https://en.wikipedia.org/w/api.php?format'
'=json&action=query&titles=Kivy&prop=revisions&rvprop=content',
on_success, on_error)
while not req.is_finished:
sleep(1)
Clock.tick()
print('result =', req.result)
print('error =', req.error)
