scrapy.http.response.text 源代码

"""
This module implements the TextResponse class which adds encoding handling and
discovering (through HTTP headers) to base Response class.

See documentation in docs/topics/request-response.rst
"""

import json
import warnings
from contextlib import suppress
from typing import Generator
from urllib.parse import urljoin

import parsel
from w3lib.encoding import (html_body_declared_encoding, html_to_unicode,
                            http_content_type_encoding, resolve_encoding)
from w3lib.html import strip_html5_whitespace

from scrapy.exceptions import ScrapyDeprecationWarning
from scrapy.http import Request
from scrapy.http.response import Response
from scrapy.utils.python import memoizemethod_noargs, to_unicode
from scrapy.utils.response import get_base_url

_NONE = object()


[文档]class TextResponse(Response): _DEFAULT_ENCODING = 'ascii' _cached_decoded_json = _NONE def __init__(self, *args, **kwargs): self._encoding = kwargs.pop('encoding', None) self._cached_benc = None self._cached_ubody = None self._cached_selector = None super().__init__(*args, **kwargs) def _set_url(self, url): if isinstance(url, str): self._url = to_unicode(url, self.encoding) else: super()._set_url(url) def _set_body(self, body): self._body = b'' # used by encoding detection if isinstance(body, str): if self._encoding is None: raise TypeError('Cannot convert unicode body - ' f'{type(self).__name__} has no encoding') self._body = body.encode(self._encoding) else: super()._set_body(body) def replace(self, *args, **kwargs): kwargs.setdefault('encoding', self.encoding) return Response.replace(self, *args, **kwargs) @property def encoding(self): return self._declared_encoding() or self._body_inferred_encoding() def _declared_encoding(self): return ( self._encoding or self._headers_encoding() or self._body_declared_encoding() ) def body_as_unicode(self): """Return body as unicode""" warnings.warn('Response.body_as_unicode() is deprecated, ' 'please use Response.text instead.', ScrapyDeprecationWarning, stacklevel=2) return self.text
[文档] def json(self): """ .. versionadded:: 2.2 Deserialize a JSON document to a Python object. """ if self._cached_decoded_json is _NONE: self._cached_decoded_json = json.loads(self.text) return self._cached_decoded_json
@property def text(self): """ Body as unicode """ # access self.encoding before _cached_ubody to make sure # _body_inferred_encoding is called benc = self.encoding if self._cached_ubody is None: charset = f'charset={benc}' self._cached_ubody = html_to_unicode(charset, self.body)[1] return self._cached_ubody def urljoin(self, url): """Join this Response's url with a possible relative url to form an absolute interpretation of the latter.""" return urljoin(get_base_url(self), url) @memoizemethod_noargs def _headers_encoding(self): content_type = self.headers.get(b'Content-Type', b'') return http_content_type_encoding(to_unicode(content_type)) def _body_inferred_encoding(self): if self._cached_benc is None: content_type = to_unicode(self.headers.get(b'Content-Type', b'')) benc, ubody = html_to_unicode(content_type, self.body, auto_detect_fun=self._auto_detect_fun, default_encoding=self._DEFAULT_ENCODING) self._cached_benc = benc self._cached_ubody = ubody return self._cached_benc def _auto_detect_fun(self, text): for enc in (self._DEFAULT_ENCODING, 'utf-8', 'cp1252'): try: text.decode(enc) except UnicodeError: continue return resolve_encoding(enc) @memoizemethod_noargs def _body_declared_encoding(self): return html_body_declared_encoding(self.body) @property def selector(self): from scrapy.selector import Selector if self._cached_selector is None: self._cached_selector = Selector(self) return self._cached_selector
[文档] def xpath(self, query, **kwargs): return self.selector.xpath(query, **kwargs)
[文档] def css(self, query): return self.selector.css(query)
[文档] def follow(self, url, callback=None, method='GET', headers=None, body=None, cookies=None, meta=None, encoding=None, priority=0, dont_filter=False, errback=None, cb_kwargs=None, flags=None): # type: (...) -> Request """ Return a :class:`~.Request` instance to follow a link ``url``. It accepts the same arguments as ``Request.__init__`` method, but ``url`` can be not only an absolute URL, but also * a relative URL * a :class:`~scrapy.link.Link` object, e.g. the result of :ref:`topics-link-extractors` * a :class:`~scrapy.selector.Selector` object for a ``<link>`` or ``<a>`` element, e.g. ``response.css('a.my_link')[0]`` * an attribute :class:`~scrapy.selector.Selector` (not SelectorList), e.g. ``response.css('a::attr(href)')[0]`` or ``response.xpath('//img/@src')[0]`` See :ref:`response-follow-example` for usage examples. """ if isinstance(url, parsel.Selector): url = _url_from_selector(url) elif isinstance(url, parsel.SelectorList): raise ValueError("SelectorList is not supported") encoding = self.encoding if encoding is None else encoding return super().follow( url=url, callback=callback, method=method, headers=headers, body=body, cookies=cookies, meta=meta, encoding=encoding, priority=priority, dont_filter=dont_filter, errback=errback, cb_kwargs=cb_kwargs, flags=flags, )
[文档] def follow_all(self, urls=None, callback=None, method='GET', headers=None, body=None, cookies=None, meta=None, encoding=None, priority=0, dont_filter=False, errback=None, cb_kwargs=None, flags=None, css=None, xpath=None): # type: (...) -> Generator[Request, None, None] """ A generator that produces :class:`~.Request` instances to follow all links in ``urls``. It accepts the same arguments as the :class:`~.Request`'s ``__init__`` method, except that each ``urls`` element does not need to be an absolute URL, it can be any of the following: * a relative URL * a :class:`~scrapy.link.Link` object, e.g. the result of :ref:`topics-link-extractors` * a :class:`~scrapy.selector.Selector` object for a ``<link>`` or ``<a>`` element, e.g. ``response.css('a.my_link')[0]`` * an attribute :class:`~scrapy.selector.Selector` (not SelectorList), e.g. ``response.css('a::attr(href)')[0]`` or ``response.xpath('//img/@src')[0]`` In addition, ``css`` and ``xpath`` arguments are accepted to perform the link extraction within the ``follow_all`` method (only one of ``urls``, ``css`` and ``xpath`` is accepted). Note that when passing a ``SelectorList`` as argument for the ``urls`` parameter or using the ``css`` or ``xpath`` parameters, this method will not produce requests for selectors from which links cannot be obtained (for instance, anchor tags without an ``href`` attribute) """ arguments = [x for x in (urls, css, xpath) if x is not None] if len(arguments) != 1: raise ValueError( "Please supply exactly one of the following arguments: urls, css, xpath" ) if not urls: if css: urls = self.css(css) if xpath: urls = self.xpath(xpath) if isinstance(urls, parsel.SelectorList): selectors = urls urls = [] for sel in selectors: with suppress(_InvalidSelector): urls.append(_url_from_selector(sel)) return super().follow_all( urls=urls, callback=callback, method=method, headers=headers, body=body, cookies=cookies, meta=meta, encoding=encoding, priority=priority, dont_filter=dont_filter, errback=errback, cb_kwargs=cb_kwargs, flags=flags, )
class _InvalidSelector(ValueError): """ Raised when a URL cannot be obtained from a Selector """ def _url_from_selector(sel): # type: (parsel.Selector) -> str if isinstance(sel.root, str): # e.g. ::attr(href) result return strip_html5_whitespace(sel.root) if not hasattr(sel.root, 'tag'): raise _InvalidSelector(f"Unsupported selector: {sel}") if sel.root.tag not in ('a', 'link'): raise _InvalidSelector("Only <a> and <link> elements are supported; " f"got <{sel.root.tag}>") href = sel.root.get('href') if href is None: raise _InvalidSelector(f"<{sel.root.tag}> element has no href attribute: {sel}") return strip_html5_whitespace(href)