无法使用 HtmlAgilityPack C# ASP.NET 在 <ul> 中获取子类别

Question

我是 Webscraping 的新手，正在尝试使用 ASP.NET C# 从具有 HTMLAgilityPack 的网站获取数据。 HTML 我要解析的结构是：

<li class='subsubnav' id='new-women-clothing'>
    <span class='cat-name'>CLOTHING</span>

    <ul>
        <li><a href="/womenswear/womens-just-in" id="just-in">Just In</a></li>

        <li><a href="/womenswear/new-season-exclusives" id="exclusives">Exclusives</a></li>

        <li><a href="/womenswear/new-season-dresses" id="dresses-&-gowns">Dresses & Gowns</a></li>

        <li><a href="/womenswear/new-season-coats" id="coats">Coats</a></li>

        <li><a href="/womenswear/new-season-jackets" id="jackets">Jackets</a></li>

        <li><a href="/womenswear/new-season-shirts-and-blouses" id="shirts-&-blouses">Shirts & Blouses</a></li>

        <li><a href="/womenswear/new-season-tops" id="tops">Tops</a></li>

        <li><a href="/womenswear/new-season-knitwear" id="knitwear">Knitwear</a></li>

        <li><a href="/womenswear/new-season-sweatshirts" id="sweatshirts">Sweatshirts</a></li>

        <li><a href="/womenswear/new-season-skirts-and-shorts" id="skirts-&-shorts">Skirts & Shorts</a></li>

        <li><a href="/womenswear/new-season-trousers" id="trousers">Trousers</a></li>

        <li><a href="/womenswear/new-season-jumpsuits" id="jumpsuits">Jumpsuits</a></li>

        <li><a href="/womenswear/new-season-jeans" id="jeans">Jeans</a></li>

        <li><a href="/womenswear/new-season-swimwear" id="swimwear">Swimwear</a></li>

        <li><a href="/womenswear/new-season-lingerie" id="lingerie">Lingerie</a></li>

        <li><a href="/womenswear/new-season-nightwear" id="nightwear">Nightwear</a></li>

        <li><a href="/womenswear/sportswear" id="sportswear">Sportswear</a></li>

        <li><a href="/womenswear/ski-wear" id="ski-wear">Ski Wear</a></li>

    </ul>

</li>

我正在获取父类别，在本例中是 CLOTHING，但我无法获取 ul 中的元素。

这是我的 C# 代码：

var html = new HtmlDocument();
html.LoadHtml(new WebClient().DownloadString("http://www.harrods.com/men/t-shirts?icid=megamenu_MW_clothing_t_shirts"));
var root = html.DocumentNode;
var nodes = root.Descendants();
var totalNodes = nodes.Count();
var dt = root.Descendants().Where(n => n.GetAttributeValue("class", "").Equals("cat-name"));

foreach(var x in dt)
{
    foreach (var element in x.Descendants("ul"))
    {
        child_data.Add(new cat_childs(element.InnerText));
    }

    data.Add(new Categories(x.InnerText,child_data));
}

test.DataSource = data;
test.DataBind();

那么如何获取 <ul> 中的 link 和锚标签的文本？

Answer 1

如果您希望迭代基于 span 和 class='cat-name'，则目标 ul 与 span 的关系是 following sibling 而不是后裔。您可以使用 SelectNodes() 从当前 span 获取后续同级元素，如下所示：

foreach (var x in dt)
{
    foreach (var element in x.SelectNodes("following-sibling::ul/li/a"))
    {
        child_data.Add(new cat_childs(element.InnerText));
    }

    data.Add(new Categories(x.InnerText,child_data));
}

更新：

似乎实际问题出在 child_data 在外循环外声明的变量。这意味着您一直在向同一个 child_data 实例添加项目。尝试在外循环内声明它，就在 foreach (var x in dt){ 之后。或者，您可以将整个代码编写为 LINQ 表达式，如下所示：

var data = (from d in dt
            let child_data = x.SelectNodes("following-sibling::ul/li/a")
                              .Select(o => new cat_childs(o.InnerText))
                              .ToList()
            select new Categories(x.InnerText, child_data)
           ).ToList();

Answer 2

使用这个 xpath。它将获取所有包含具有 class='cat-name' 的的

。之后它会选择所有被

包围的。

//If the span has no influence on what you want you can simply use: 
//HtmlNodeCollection hNC = htmlDoc.DocumentNode.SelectNodes("//ul/li/a");

HtmlNodeCollection hNC = htmlDoc.DocumentNode.SelectNodes("//li/span[@class='cat-name']/parent::*/ul/li");
foreach (HtmlNode h in hNC)
{
    Console.Write(h.InnerText+" ");
    Console.WriteLine(h.GetAttributeValue("href", ""));
}

无法使用 HtmlAgilityPack C# ASP.NET 在 <ul> 中获取子类别

Unable to get Child Categories inside <ul> using HtmlAgilityPack C# ASP.NET

c#

asp.net

web-scraping

html-agility-pack