scrapy.selector.unified 源代码

XPath selectors based on lxml

from parsel import Selector as _ParselSelector
from scrapy.utils.trackref import object_ref
from scrapy.utils.python import to_bytes
from scrapy.http import HtmlResponse, XmlResponse

__all__ = ['Selector', 'SelectorList']

def _st(response, st):
    if st is None:
        return 'xml' if isinstance(response, XmlResponse) else 'html'
    return st

def _response_from_text(text, st):
    rt = XmlResponse if st == 'xml' else HtmlResponse
    return rt(url='about:blank', encoding='utf-8',
              body=to_bytes(text, 'utf-8'))

[文档]class SelectorList(_ParselSelector.selectorlist_cls, object_ref): """ The :class:`SelectorList` class is a subclass of the builtin ``list`` class, which provides a few additional methods. """
[文档]class Selector(_ParselSelector, object_ref): """ An instance of :class:`Selector` is a wrapper over response to select certain parts of its content. ``response`` is an :class:`~scrapy.http.HtmlResponse` or an :class:`~scrapy.http.XmlResponse` object that will be used for selecting and extracting data. ``text`` is a unicode string or utf-8 encoded text for cases when a ``response`` isn't available. Using ``text`` and ``response`` together is undefined behavior. ``type`` defines the selector type, it can be ``"html"``, ``"xml"`` or ``None`` (default). If ``type`` is ``None``, the selector automatically chooses the best type based on ``response`` type (see below), or defaults to ``"html"`` in case it is used together with ``text``. If ``type`` is ``None`` and a ``response`` is passed, the selector type is inferred from the response type as follows: * ``"html"`` for :class:`~scrapy.http.HtmlResponse` type * ``"xml"`` for :class:`~scrapy.http.XmlResponse` type * ``"html"`` for anything else Otherwise, if ``type`` is set, the selector type will be forced and no detection will occur. """ __slots__ = ['response'] selectorlist_cls = SelectorList def __init__(self, response=None, text=None, type=None, root=None, **kwargs): if response is not None and text is not None: raise ValueError(f'{self.__class__.__name__}.__init__() received ' 'both response and text') st = _st(response, type) if text is not None: response = _response_from_text(text, st) if response is not None: text = response.text kwargs.setdefault('base_url', response.url) self.response = response super().__init__(text=text, type=st, root=root, **kwargs)