c# - 从具有特定类名的元素中选择值

Question

我在解析外部 html 文件时遇到对象引用错误，我认为这是因为并非所有选定的元素都具有类名。这是我的代码:

foreach (HtmlNode link in doc.DocumentNode.Descendants("li").Where(i => i.Attributes["class"].Value == "name"))
{
    string result = link.InnerText.Trim().Replace(" ", "");
    Console.WriteLine(result);
}

如何只选择类名为“name”的值？

这是我要解析的 html 代码:

<li>
    <span class="name">
        <a href="/players/joe-bloggs.html">Joe,&nbsp;Bloggs</a>
    </span>

    <span class="country">
        <img src="/img/flags/15x15/USA.gif" alt="USA"/>
        United States
    </span>
</li>
<li>
    <span class="name">
        <a href="/players/joe-bloggs.html">Joe,&nbsp;Bloggs</a>
    </span>

    <span class="country">
        <img src="/img/flags/15x15/USA.gif" alt="USA"/>
        United States
    </span>
</li>
<li>
    <span class="name">
        <a href="/players/joe-bloggs.html">Joe,&nbsp;Bloggs</a>
    </span>

    <span class="country">
        <img src="/img/flags/15x15/RSA.gif" alt="RSA"/>
        South Africa
    </span>
</li>

Answer 1

您应该选择 a 元素而不是 li 元素。及其具有 class 属性的 span 元素。我建议你使用谓词:

var links = doc.DocumentNode.SelectNodes("//li/span[@class='name']/a");

此 xpath 选择所有 span 元素，其 class 属性等于 name，然后选择 a 元素.

foreach (var a in links)
    Console.WriteLine(a.InnerText);

对于您的示例 HTML 输出是:

Joe, Bloggs
Joe, Bloggs
Joe, Bloggs

旁注 - 您可以使用 HttpUtility.HtmlDecode(a.InnerText) 获取解码文本(不仅   将被替换)。

---

更新:解析播放器

var players = from p in doc.DocumentNode.SelectNodes("//li")
              let name = p.SelectSingleNode("span[@class='name']/a")
              let country = p.SelectSingleNode("span[@class='country']")
              select new
              {
                  Name = (name == null) ? null : 
                         HttpUtility.HtmlDecode(name.InnerText.Trim()),
                  Country = (country == null) ? null :
                         HttpUtility.HtmlDecode(country.InnerText.Trim())
              };

结果:

[
  {
    Name: "Joe, Bloggs",
    Country: "United States"
  },
  {
    Name: "Joe, Bloggs",
    Country: "United States"
  },
  {
    Name: "Joe, Bloggs",
    Country: "South Africa"
  }
]