ruby-on-rails - 使用 Mechanize 和 Nokogiri 从 <a> 标签中提取 href 参数

Question

我有这个 HTML:

<div id="main">
    <li>
        <h2>
            <a href="https://www.congress.gov/bill/99th-congress/senate-joint-resolution/427">S.J.Res.427</a>
        </h2>
    </li>
    <li>
        ....
    </li>
</div>

我想提取<a>的href值标签。

使用 Mechanize 和 Nokogiri 我做到了:

activity_list = member.search('#main li')
activity_list.each do |link| 
    activity_link = link.at("h2 a[href]")
end

但我得到了 TypeError: no implicit conversion of nil into String
怎么了？

Answer 1

您正在寻找 #attr方法:

html = Nokogiri::HTML('<div id="main"><li><h2>
  <a href="https://www.congress.gov/bill/99th-congress/senate-joint-resolution/427">S.J.Res.427</a>
</h2></li></div>')
html.search('#main li').each do |link|
  #                         ⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓
  puts link.at("h2 a[href]").attr('href')
end
#⇒ https://www.congress.gov/bill/99th-congress/senate-joint-resolution/427