From e6c5292a7c4391642897ee31ea2ded889b3b88dc Mon Sep 17 00:00:00 2001 From: Eugenio Lacuesta Date: Wed, 20 Nov 2019 09:29:55 -0300 Subject: [PATCH] Response.follow_all: Specific exception for invalid selectors --- scrapy/http/response/text.py | 31 ++++++++++++++++++------------- 1 file changed, 18 insertions(+), 13 deletions(-) diff --git a/scrapy/http/response/text.py b/scrapy/http/response/text.py index 74017b5aa..5110b4bd4 100644 --- a/scrapy/http/response/text.py +++ b/scrapy/http/response/text.py @@ -5,17 +5,18 @@ discovering (through HTTP headers) to base Response class. See documentation in docs/topics/request-response.rst """ -import six -from six.moves.urllib.parse import urljoin +from contextlib import suppress import parsel -from w3lib.encoding import html_to_unicode, resolve_encoding, \ - html_body_declared_encoding, http_content_type_encoding +import six +from six.moves.urllib.parse import urljoin +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.response import Response -from scrapy.utils.response import get_base_url from scrapy.utils.python import memoizemethod_noargs, to_native_str +from scrapy.utils.response import get_base_url class TextResponse(Response): @@ -197,10 +198,8 @@ class TextResponse(Response): selector_list = self.xpath(xpath) urls = [] for selector in selector_list: - try: + with suppress(_InvalidSelector): urls.append(_url_from_selector(selector)) - except ValueError: - pass return super(TextResponse, self).follow_all( urls=urls, callback=callback, @@ -217,18 +216,24 @@ class TextResponse(Response): ) +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, six.string_types): # e.g. ::attr(href) result return strip_html5_whitespace(sel.root) if not hasattr(sel.root, 'tag'): - raise ValueError("Unsupported selector: %s" % sel) + raise _InvalidSelector("Unsupported selector: %s" % sel) if sel.root.tag not in ('a', 'link'): - raise ValueError("Only and elements are supported; got <%s>" % - sel.root.tag) + raise _InvalidSelector("Only and elements are supported; got <%s>" % + sel.root.tag) href = sel.root.get('href') if href is None: - raise ValueError("<%s> element has no href attribute: %s" % - (sel.root.tag, sel)) + raise _InvalidSelector("<%s> element has no href attribute: %s" % + (sel.root.tag, sel)) return strip_html5_whitespace(href)