mirror of https://github.com/scrapy/scrapy.git
101 lines
3.0 KiB
Python
101 lines
3.0 KiB
Python
"""
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Base class for Scrapy spiders
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See documentation in docs/topics/spiders.rst
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"""
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from __future__ import annotations
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import logging
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from typing import TYPE_CHECKING, Optional
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from scrapy import signals
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from scrapy.http import Request
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from scrapy.utils.trackref import object_ref
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from scrapy.utils.url import url_is_from_spider
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if TYPE_CHECKING:
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from scrapy.crawler import Crawler
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class Spider(object_ref):
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"""Base class for scrapy spiders. All spiders must inherit from this
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class.
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"""
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name: Optional[str] = None
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custom_settings: Optional[dict] = None
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def __init__(self, name=None, **kwargs):
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if name is not None:
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self.name = name
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elif not getattr(self, 'name', None):
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raise ValueError(f"{type(self).__name__} must have a name")
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self.__dict__.update(kwargs)
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if not hasattr(self, 'start_urls'):
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self.start_urls = []
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@property
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def logger(self):
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logger = logging.getLogger(self.name)
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return logging.LoggerAdapter(logger, {'spider': self})
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def log(self, message, level=logging.DEBUG, **kw):
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"""Log the given message at the given log level
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This helper wraps a log call to the logger within the spider, but you
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can use it directly (e.g. Spider.logger.info('msg')) or use any other
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Python logger too.
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"""
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self.logger.log(level, message, **kw)
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@classmethod
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def from_crawler(cls, crawler, *args, **kwargs):
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spider = cls(*args, **kwargs)
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spider._set_crawler(crawler)
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return spider
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def _set_crawler(self, crawler: Crawler):
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self.crawler = crawler
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self.settings = crawler.settings
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crawler.signals.connect(self.close, signals.spider_closed)
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def start_requests(self):
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if not self.start_urls and hasattr(self, 'start_url'):
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raise AttributeError(
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"Crawling could not start: 'start_urls' not found "
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"or empty (but found 'start_url' attribute instead, "
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"did you miss an 's'?)")
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for url in self.start_urls:
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yield Request(url, dont_filter=True)
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def _parse(self, response, **kwargs):
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return self.parse(response, **kwargs)
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def parse(self, response, **kwargs):
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raise NotImplementedError(f'{self.__class__.__name__}.parse callback is not defined')
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@classmethod
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def update_settings(cls, settings):
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settings.setdict(cls.custom_settings or {}, priority='spider')
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@classmethod
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def handles_request(cls, request):
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return url_is_from_spider(request.url, cls)
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@staticmethod
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def close(spider, reason):
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closed = getattr(spider, 'closed', None)
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if callable(closed):
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return closed(reason)
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def __str__(self):
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return f"<{type(self).__name__} {self.name!r} at 0x{id(self):0x}>"
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__repr__ = __str__
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# Top-level imports
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from scrapy.spiders.crawl import CrawlSpider, Rule
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from scrapy.spiders.feed import XMLFeedSpider, CSVFeedSpider
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from scrapy.spiders.sitemap import SitemapSpider
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