如何选择具有值未知的给定属性的标记？

I'm guessing this is a trivial question for someone with a bit of experience with Nokogiri, but I haven't been able to find an answer in the documentation or tutorials I've found online.

我猜这对于对Nokogiri有一点经验的人来说是一个微不足道的问题，但是我在网上找到的文档或教程中找不到答案。

I have a Nokogiri document like this:

我有一个像这样的Nokogiri文件：

page = Nokogiri::HTML(open("http://www.example.com"))

And the page contains the following tag:

该页面包含以下标记：

<a title="could be anything" href="http://www.example.com/foo"></a>

How do I get the value of href if the value of title is unknown?

如果title的值未知，我如何获得href的值？

3 个解决方案

#1

If you want the value of the href attribute for a elements having a title attribute you can use Nokogiri's xpath as follows:

如果你想要具有title属性的元素的href属性的值，你可以使用Nokogiri的xpath，如下所示：

require 'nokogiri'

doc = Nokogiri::HTML(File.open('sample.html'))

a_with_title = doc.xpath('//a[@title]').map { |e| puts e['href'] }

If you want to select from an URL online you can use

如果您想从在线URL中选择，您可以使用

require 'nokogiri'
require 'open-uri'

doc = Nokogiri::HTML(open('http://*.com/'))

a_with_title = doc.xpath('//a[@title]').map { |e| puts e['href'] }

#2

I finally figured it out. I believe, the following will work to select the href from the first link element with a title attribute: page.css('a[title]')[0]['href'].

我终于弄明白了。我相信，以下将使用title属性从第一个link元素中选择href：page.css（'a [title]'）[0] ['href']。

I had thought page.css('a[title]') was selecting the value of the title attribute, but in fact it selects the entire element. You can then reference this element to get values from it.

我原以为page.css（'a [title]'）选择了title属性的值，但实际上它选择了整个元素。然后，您可以引用此元素以从中获取值。

#3

require 'nokogiri'


doc = Nokogiri::HTML::DocumentFragment.parse <<-SCRIPT
<a title="xx" href="http://www.example1.com/foo1"></a>
<a title="aa" href="http://www.example2.com/foo2"></a>
<a id=5 href="http://www.foo.com/foo3"></a>
<a title="zz" href="http://www.example3.com/foo4"></a>
<a id=5 href="http://www.test.com/foo5"></a>
 SCRIPT

p doc.search("a").map { |nd|  nd['href'] if nd.key?('title')}.compact

#=> ["http://www.example1.com/foo1", "http://www.example2.com/foo2", "http://www.example3.com/foo4"]

#1