Nokogiri 无法找到以“(”开头的 XPath
Nokogiri unable to find XPath beginning with "("
我必须使用以下 XPath：
(//li[@id='result_0']//span[contains(@class,'s-price')])[2]
我的代码如下所示：
require 'mechanize'
agent = Mechanize.new
page = agent.get(site_url)
element = page.at("(//li[@id='result_0']//span[contains(@class,'s-price')])[2]")
Firebug 能够使用相同的 XPath 找到元素，但是当我在 Nokogiri 中使用这个 XPath 时，出现以下错误：
Nokogiri::CSS::SyntaxError: unexpected '(' after ''
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/css/parser_extras.rb:87:in `on_error'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/2.2.0/racc/parser.rb:258:in `_racc_do_parse_c'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/2.2.0/racc/parser.rb:258:in `do_parse'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/css/parser_extras.rb:62:in `parse'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/css/parser_extras.rb:79:in `xpath_for'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/css.rb:23:in `xpath_for'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:198:in `block in xpath_query_from_css_rule'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:197:in `map'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:197:in `xpath_query_from_css_rule'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:52:in `block in search'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:51:in `map'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:51:in `search'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:67:in `at'
from (irb):11
from /home/shubham/.rbenv/versions/2.2.2/bin/irb:11:in `<main>'
Nokogiri::CSS::SyntaxError:
根据错误判断，您正试图在 css 方法中使用 XPath 表达式，而该方法需要 CSS 选择器。使用xpath()方法。
我必须使用以下 XPath：
(//li[@id='result_0']//span[contains(@class,'s-price')])[2]
我的代码如下所示：
require 'mechanize'
agent = Mechanize.new
page = agent.get(site_url)
element = page.at("(//li[@id='result_0']//span[contains(@class,'s-price')])[2]")
Firebug 能够使用相同的 XPath 找到元素，但是当我在 Nokogiri 中使用这个 XPath 时，出现以下错误：
Nokogiri::CSS::SyntaxError: unexpected '(' after ''
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/css/parser_extras.rb:87:in `on_error'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/2.2.0/racc/parser.rb:258:in `_racc_do_parse_c'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/2.2.0/racc/parser.rb:258:in `do_parse'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/css/parser_extras.rb:62:in `parse'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/css/parser_extras.rb:79:in `xpath_for'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/css.rb:23:in `xpath_for'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:198:in `block in xpath_query_from_css_rule'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:197:in `map'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:197:in `xpath_query_from_css_rule'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:52:in `block in search'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:51:in `map'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:51:in `search'
from /home/shubham/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/nokogiri-1.6.7.2/lib/nokogiri/xml/searchable.rb:67:in `at'
from (irb):11
from /home/shubham/.rbenv/versions/2.2.2/bin/irb:11:in `<main>'
Nokogiri::CSS::SyntaxError:
根据错误判断，您正试图在 css 方法中使用 XPath 表达式，而该方法需要 CSS 选择器。使用xpath()方法。