"""
This module provides some useful functions for working with
scrapy.http.Request objects
"""
import hashlib
from typing import Dict, Iterable, Optional, Tuple, Union
from urllib.parse import urlunparse
from weakref import WeakKeyDictionary
from w3lib.http import basic_auth_header
from w3lib.url import canonicalize_url
from scrapy import Request, Spider
from scrapy.utils.httpobj import urlparse_cached
from scrapy.utils.misc import load_object
from scrapy.utils.python import to_bytes, to_unicode
_fingerprint_cache: "WeakKeyDictionary[Request, Dict[Tuple[Optional[Tuple[bytes, ...]], bool], str]]"
_fingerprint_cache = WeakKeyDictionary()
def request_fingerprint(
request: Request,
include_headers: Optional[Iterable[Union[bytes, str]]] = None,
keep_fragments: bool = False,
) -> str:
"""
Return the request fingerprint.
The request fingerprint is a hash that uniquely identifies the resource the
request points to. For example, take the following two urls:
http://www.example.com/query?id=111&cat=222
http://www.example.com/query?cat=222&id=111
Even though those are two different URLs both point to the same resource
and are equivalent (i.e. they should return the same response).
Another example are cookies used to store session ids. Suppose the
following page is only accessible to authenticated users:
http://www.example.com/members/offers.html
Lot of sites use a cookie to store the session id, which adds a random
component to the HTTP Request and thus should be ignored when calculating
the fingerprint.
For this reason, request headers are ignored by default when calculating
the fingerprint. If you want to include specific headers use the
include_headers argument, which is a list of Request headers to include.
Also, servers usually ignore fragments in urls when handling requests,
so they are also ignored by default when calculating the fingerprint.
If you want to include them, set the keep_fragments argument to True
(for instance when handling requests with a headless browser).
"""
headers: Optional[Tuple[bytes, ...]] = None
if include_headers:
headers = tuple(to_bytes(h.lower()) for h in sorted(include_headers))
cache = _fingerprint_cache.setdefault(request, {})
cache_key = (headers, keep_fragments)
if cache_key not in cache:
fp = hashlib.sha1()
fp.update(to_bytes(request.method))
fp.update(to_bytes(canonicalize_url(request.url, keep_fragments=keep_fragments)))
fp.update(request.body or b'')
if headers:
for hdr in headers:
if hdr in request.headers:
fp.update(hdr)
for v in request.headers.getlist(hdr):
fp.update(v)
cache[cache_key] = fp.hexdigest()
return cache[cache_key]
def request_authenticate(request: Request, username: str, password: str) -> None:
"""Authenticate the given request (in place) using the HTTP basic access
authentication mechanism (RFC 2617) and the given username and password
"""
request.headers['Authorization'] = basic_auth_header(username, password)
def request_httprepr(request: Request) -> bytes:
"""Return the raw HTTP representation (as bytes) of the given request.
This is provided only for reference since it's not the actual stream of
bytes that will be send when performing the request (that's controlled
by Twisted).
"""
parsed = urlparse_cached(request)
path = urlunparse(('', '', parsed.path or '/', parsed.params, parsed.query, ''))
s = to_bytes(request.method) + b" " + to_bytes(path) + b" HTTP/1.1\r\n"
s += b"Host: " + to_bytes(parsed.hostname or b'') + b"\r\n"
if request.headers:
s += request.headers.to_string() + b"\r\n"
s += b"\r\n"
s += request.body
return s
def referer_str(request: Request) -> Optional[str]:
""" Return Referer HTTP header suitable for logging. """
referrer = request.headers.get('Referer')
if referrer is None:
return referrer
return to_unicode(referrer, errors='replace')
[文档]def request_from_dict(d: dict, *, spider: Optional[Spider] = None) -> Request:
"""Create a :class:`~scrapy.Request` object from a dict.
If a spider is given, it will try to resolve the callbacks looking at the
spider for methods with the same name.
"""
request_cls = load_object(d["_class"]) if "_class" in d else Request
kwargs = {key: value for key, value in d.items() if key in request_cls.attributes}
if d.get("callback") and spider:
kwargs["callback"] = _get_method(spider, d["callback"])
if d.get("errback") and spider:
kwargs["errback"] = _get_method(spider, d["errback"])
return request_cls(**kwargs)
def _get_method(obj, name):
"""Helper function for request_from_dict"""
name = str(name)
try:
return getattr(obj, name)
except AttributeError:
raise ValueError(f"Method {name!r} not found in: {obj}")