如何在 C# 中使用 XPath 选择节点？
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How to select nodes with XPath in C#?
提问by Joe
Simple question, I just want to select the text from the <Template> tag. Here's what I have, but the Xpath doesn't match anything.
简单的问题，我只想从 <Template> 标签中选择文本。这是我所拥有的，但 Xpath 不匹配任何东西。
public static void TestXPath()
{
string xmlText = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>";
xmlText += "<Properties xmlns=\"http://schemas.openxmlformats.org/officeDocument/2006/extended-properties\" xmlns:vt=\"http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes\">";
xmlText += "<Template>Normal</Template> <TotalTime>1</TotalTime> <Pages>1</Pages> <Words>6</Words>";
xmlText += "</Properties>";
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(new System.IO.StringReader(xmlText));
foreach (XmlNode node in xmlDoc.SelectNodes("//Template"))
{
Console.WriteLine("{0}: {1}", node.Name, node.InnerText);
}
}
采纳答案by Jon Skeet
You need to use an XmlNamespaceManagerbecause the Template element is in a namespace:
您需要使用 anXmlNamespaceManager因为 Template 元素位于命名空间中：
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(new System.IO.StringReader(xmlText));
XmlNamespaceManager manager = new XmlNamespaceManager(xmlDoc.NameTable);
manager.AddNamespace("ns",
"http://schemas.openxmlformats.org/officeDocument/2006/extended-properties");
foreach (XmlNode node in xmlDoc.SelectNodes("//ns:Template", manager))
{
Console.WriteLine("{0}: {1}", node.Name, node.InnerText);
}
回答by Marc Gravell
That is a namespace issue; you need to get the name-table, pick an alias, and use that in your query. Or perhaps (in this case) try GetElementsByTagName.
这是一个命名空间问题；您需要获取名称表，选择一个别名，并在您的查询中使用它。或者（在这种情况下）尝试GetElementsByTagName.
XmlNamespaceManager mgr = new XmlNamespaceManager(xmlDoc.NameTable);
mgr.AddNamespace("x",
"http://schemas.openxmlformats.org/officeDocument/2006/extended-properties");
foreach (XmlNode node in xmlDoc.SelectNodes("//x:Template", mgr))
{
Console.WriteLine("{0}: {1}", node.Name, node.InnerText);
}
Or:
或者：
foreach (XmlNode node in xmlDoc.GetElementsByTagName("Template"))
{
Console.WriteLine("{0}: {1}", node.Name, node.InnerText);
}
回答by PierrOz
Here your xpath expression requires a namespace resolution. you have to instanciate a XmlNamespaceManager and use it in your SelectNodes.
这里您的 xpath 表达式需要命名空间解析。你必须实例化一个 XmlNamespaceManager 并在你的 SelectNodes 中使用它。
this sample should work
这个样本应该工作
public static void TestXPath()
{
string xmlText = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>";
xmlText += "<Properties xmlns=\"http://schemas.openxmlformats.org/officeDocument/2006/extended-properties\" xmlns:vt=\"http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes\">";
xmlText += "<Template>Normal</Template> <TotalTime>1</TotalTime> <Pages>1</Pages> <Words>6</Words>";
xmlText += "</Properties>";
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(new System.IO.StringReader(xmlText));
XmlNamespaceManager nsmgr = new XmlNamespaceManager(xmlDoc.NameTable);
nsmgr.AddNamespace("res", "http://schemas.openxmlformats.org/officeDocument/2006/extended-properties");
foreach (XmlNode node in xmlDoc.SelectNodes("//res:Template", nsmgr))
{
Console.WriteLine("{0}: {1}", node.Name, node.InnerText);
}
}
you can also get the default namespace by using and write
您还可以通过使用和编写来获取默认命名空间
string s = xmlDoc.DocumentElement.GetNamespaceOfPrefix("");
nsmgr.AddNamespace("ns", s);
回答by Joe
Why do you need the namespace here anyway? just get rid of these
为什么这里需要命名空间？摆脱这些
xmlns=\"http://schemas.openxmlformats.org/officeDocument/2006/extended-properties\"
xmlns:vt=\"http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes\"
and your selection will work.
您的选择将起作用。
