"""
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
"""
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.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
[docs]class TextResponse(Response):
_DEFAULT_ENCODING = 'ascii'
def __init__(self, *args, **kwargs):
self._encoding = kwargs.pop('encoding', None)
self._cached_benc = None
self._cached_ubody = None
self._cached_selector = None
super(TextResponse, self).__init__(*args, **kwargs)
def _set_url(self, url):
if isinstance(url, str):
self._url = to_unicode(url, self.encoding)
else:
super(TextResponse, self)._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 - %s has no encoding' %
type(self).__name__)
self._body = body.encode(self._encoding)
else:
super(TextResponse, self)._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()
[docs] def body_as_unicode(self):
"""Return body as unicode"""
return self.text
@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 = 'charset=%s' % 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
[docs] def xpath(self, query, **kwargs):
return self.selector.xpath(query, **kwargs)
[docs] def css(self, query):
return self.selector.css(query)
[docs] 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(TextResponse, self).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,
)
[docs] 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(TextResponse, self).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("Unsupported selector: %s" % sel)
if sel.root.tag not in ('a', 'link'):
raise _InvalidSelector("Only <a> and <link> elements are supported; got <%s>" %
sel.root.tag)
href = sel.root.get('href')
if href is None:
raise _InvalidSelector("<%s> element has no href attribute: %s" %
(sel.root.tag, sel))
return strip_html5_whitespace(href)