Method from_crawler

tests/spiders.py:549–552

(cls, crawler, *args, **kwargs)

class HeadersReceivedCallbackSpider(MetaSpider):
    @classmethod
    def from_crawler(cls, crawler, *args, **kwargs):
        spider = super().from_crawler(crawler, *args, **kwargs)
        crawler.signals.connect(spider.headers_received, signals.headers_received)
        return spider

    async def start(self):
        yield Request(