C# Html Agility Pack，从节点中选择节点
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Html Agility Pack, SelectNodes from a node
提问by thatsIT
Why does this pick all of my <li>elements in my document?
为什么这会选择<li>我文档中的所有元素？
HtmlWeb web = new HtmlWeb();
HtmlDocument doc = web.Load(url);
var travelList = new List<Page>();
var liOfTravels = doc.DocumentNode.SelectSingleNode("//div[@id='myTrips']")
.SelectNodes("//li");
What I want is to get all <li>elements in the <div>with an idof "myTrips".
我想要的是使用“myTrips”获取所有<li>元素。<div>id
采纳答案by ChristiaanV
It's a bit confusing because you're expecting that it would do a selectNodes on only the div with id "myTrips", however if you do another SelectNodes("//li") it will performn another search from the top of the document.
这有点令人困惑，因为您期望它仅在 id 为“myTrips”的 div 上执行 selectNodes，但是如果您执行另一个 SelectNodes("//li")，它将从文档顶部执行另一次搜索。
I fixed this by combining the statement into one, but that would only work on a webpage where you have only one div with an id "mytrips". The query would look like this:
我通过将语句合并为一个来解决此问题，但这仅适用于只有一个 div 且 ID 为“mytrips”的网页。查询将如下所示：
doc.DocumentNode.SelectNodes("//div[@id='myTrips'] //li");
doc.DocumentNode.SelectNodes("//div[@id='myTrips'] //li");
回答by vfportero
You can do this with a Linq query:
您可以使用 Linq 查询执行此操作：
HtmlWeb web = new HtmlWeb();
HtmlDocument doc = web.Load(url);
var travelList = new List<HtmlNode>();
foreach (var matchingDiv in doc.DocumentNode.DescendantNodes().Where(n=>n.Name == "div" && n.Id == "myTrips"))
{
travelList.AddRange(matchingDiv.DescendantNodes().Where(n=> n.Name == "li"));
}
I hope it helps
我希望它有帮助
回答by Paul
This seems counter intuitive to me aswell, if you run a selectNodesmethod on a particular node I thought it would only search for stuff underneath that node, not in the document in general.
这对我来说似乎也违反直觉，如果您selectNodes在特定节点上运行一个方法，我认为它只会搜索该节点下的内容，而不是一般的文档。
Anyway OP if you change this line :
无论如何，如果您更改此行，请执行以下操作：
var liOfTravels =
doc.DocumentNode.SelectSingleNode("//div[@id='myTrips']").SelectNodes("//li");
TO:
到：
var liOfTravels =
doc.DocumentNode.SelectSingleNode("//div[@id='myTrips']").SelectNodes("li");
I think you'll be ok, i've just had the same issue and that fixed it for me. Im not sure though if the li would have to be a direct child of the node you have.
我想你会没事的，我刚刚遇到了同样的问题，并且为我解决了这个问题。我不确定 li 是否必须是您拥有的节点的直接子节点。
回答by greenoldman
var liOfTravels = doc.DocumentNode.SelectSingleNode("//div[@id='myTrips']")
.SelectNodes(".//li");
Note the dot in the second line. Basically in this regard HTMLAgitilityPack completely relies on XPath syntax, however the result is non-intuitive, because those queries are effectively the same:
注意第二行中的点。基本上在这方面 HTMLAgitilityPack 完全依赖于 XPath 语法，但是结果是不直观的，因为这些查询实际上是相同的：
doc.DocumentNode.SelectNodes("//li");
some_deeper_node.SelectNodes("//li");
回答by Rob
Creating a new node can be beneficial in some situations and lets you use the xpaths more intuitively. I've found this useful in a couple of places.
在某些情况下，创建一个新节点可能是有益的，并且可以让您更直观地使用 xpath。我发现这在几个地方很有用。
var myTripsDiv = doc.DocumentNode.SelectSingleNode("//div[@id='myTrips']");
var myTripsNode = HtmlNode.CreateNode(myTripsDiv.InnerHtml);
var liOfTravels = myTripsNode.SelectNodes("//li");
