报价问题（红宝石）

Question

知道如何将正确的参数传递给 xpath 吗？必须有一些关于如何使用单引号/双引号的东西。当我使用变量时

parser_xpath_identificator = "'//table/tbody[@id=\"threadbits_forum_251\"]/tr'" 给了我一个不正确的值或

parser_xpath_identificator = "'//table/tbody[@id="threadbits_forum_251"]/tr'" 给我一个错误语法错误，意外的 tIDENTIFIER，期待 $end

require 'rubygems'
require 'mechanize'

parser_xpath_identificator = "'//table/tbody[@id=\"threadbits_forum_251\"]/tr'"
#   parser_xpath_identificator = "'//table/tbody[@id="threadbits_forum_251"]/tr'"
    #gives an error: syntax error, unexpected tIDENTIFIER, expecting $end

agent = WWW::Mechanize.new
page = agent.get("http://www.vbulletin.org/forum/index.php")
page = page.link_with(:text=>'vB4 General Discussions').click
puts "Page title: #{page.title}"
puts "\nfrom variable: #{page.parser.xpath(parser_xpath_identificator).length}"
puts "directly: #{page.parser.xpath('//table/tbody[@id="threadbits_forum_251"]/tr').length}"

Answer 1

在这两种情况下，您都将单引号直接嵌套在双引号内，我认为这是不正确的。试试这个：

parser_xpath_identificator = '//table/tbody[@id="threadbits_forum_251"]/tr'