Source code for scrapy.downloadermiddlewares.offsite

from __future__ import annotations

import logging
import re
import warnings
from typing import TYPE_CHECKING, Set

from scrapy import Request, Spider, signals
from scrapy.crawler import Crawler
from scrapy.exceptions import IgnoreRequest
from scrapy.statscollectors import StatsCollector
from scrapy.utils.httpobj import urlparse_cached

if TYPE_CHECKING:
    # typing.Self requires Python 3.11
    from typing_extensions import Self

logger = logging.getLogger(__name__)


[docs]class OffsiteMiddleware: @classmethod def from_crawler(cls, crawler: Crawler) -> Self: assert crawler.stats o = cls(crawler.stats) crawler.signals.connect(o.spider_opened, signal=signals.spider_opened) crawler.signals.connect(o.request_scheduled, signal=signals.request_scheduled) return o def __init__(self, stats: StatsCollector): self.stats = stats self.domains_seen: Set[str] = set() def spider_opened(self, spider: Spider) -> None: self.host_regex: re.Pattern[str] = self.get_host_regex(spider) def request_scheduled(self, request: Request, spider: Spider) -> None: self.process_request(request, spider) def process_request(self, request: Request, spider: Spider) -> None: if request.dont_filter or self.should_follow(request, spider): return None domain = urlparse_cached(request).hostname if domain and domain not in self.domains_seen: self.domains_seen.add(domain) logger.debug( "Filtered offsite request to %(domain)r: %(request)s", {"domain": domain, "request": request}, extra={"spider": spider}, ) self.stats.inc_value("offsite/domains", spider=spider) self.stats.inc_value("offsite/filtered", spider=spider) raise IgnoreRequest def should_follow(self, request: Request, spider: Spider) -> bool: regex = self.host_regex # hostname can be None for wrong urls (like javascript links) host = urlparse_cached(request).hostname or "" return bool(regex.search(host)) def get_host_regex(self, spider: Spider) -> re.Pattern[str]: """Override this method to implement a different offsite policy""" allowed_domains = getattr(spider, "allowed_domains", None) if not allowed_domains: return re.compile("") # allow all by default url_pattern = re.compile(r"^https?://.*$") port_pattern = re.compile(r":\d+$") domains = [] for domain in allowed_domains: if domain is None: continue if url_pattern.match(domain): message = ( "allowed_domains accepts only domains, not URLs. " f"Ignoring URL entry {domain} in allowed_domains." ) warnings.warn(message) elif port_pattern.search(domain): message = ( "allowed_domains accepts only domains without ports. " f"Ignoring entry {domain} in allowed_domains." ) warnings.warn(message) else: domains.append(re.escape(domain)) regex = rf'^(.*\.)?({"|".join(domains)})$' return re.compile(regex)