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