all Python 3urllib.requestterm

urllib.request.HTTPErrorProcessor

errors and redirects

A post-processor for HTTP responses: everything outside the 2xx range goes to the error-handling chain.

Syntax

urllib.request.HTTPErrorProcessor()

It is what decides that a 3xx, 401 or 500 is an event rather than a response: redirects, authentication and finally HTTPDefaultErrorHandler with HTTPError take over. It sits last in the chain (handler_order 1000). For file: and data: it is never called — there are no HTTP codes, and resp.status is None.

Examples

import urllib.request
print(urllib.request.HTTPErrorProcessor.handler_order)  # → 1000
with urllib.request.urlopen('data:,x') as resp:
    print(resp.status)  # → None

import email.message, io, urllib.error, urllib.request, urllib.response
def reply(req, code, body=b'', **headers):
    msg = email.message.Message()
    for name, value in headers.items():
        msg[name.replace('_', '-')] = value
    resp = urllib.response.addinfourl(io.BytesIO(body), msg, req.full_url, code)
    resp.msg = 'demo'
    return resp
class Server(urllib.request.BaseHandler):
    handler_order = 100
    def http_open(self, req):
        return reply(req, 503, b'busy')
try:
    urllib.request.build_opener(Server).open('http://example.com/')
except urllib.error.HTTPError as e:
    print('HTTPError', e.code)  # → HTTPError 503

See also

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