XPath异常SelectSingleNode

Question

private void toolStripButton2_Click(object sender, EventArgs e)
{
        XmlTextReader reader = new XmlTextReader("component.xml");
        XmlDocument doc = new XmlDocument();
        doc.Load(reader);
        string path4 = treeView1.SelectedNode.FullPath.ToString();

        XmlNode nodeToRemove = doc.SelectSingleNode(path4);
        XmlNode parentNode = nodeToRemove.ParentNode;
        parentNode.RemoveChild(nodeToRemove);
 }

我在xml中使用以下代码删除节点，但它生成了以下错误。请帮帮我。

这是我的xml的一部分。我想删除用户选择的路径条目。对于选择路径，我生成了treeview。变量path4来自树视图选择的路径。

<WindowEntries>
<WindowEntry>
  <Name>tbwUnitOverview</Name>
  <View>TRN_UNIT</View>
  <LU>TrnUnit</LU>
  <DefaultWindowText />
  <Flags>0</Flags>
</WindowEntry>
<WindowEntry>
  <Name>tbwBrandOverView</Name>
  <View>TRN_BRAND</View>
  <LU>TrnBrand</LU>
  <DefaultWindowText />
  <Flags>0</Flags>
</WindowEntry>
<WindowEntry>
  <Name>tbwProductCategory</Name>
  <View>TRN_PROD_CATEGORY</View>
  <LU>TrnProdCategory</LU>
  <DefaultWindowText />
  <Flags>0</Flags>
</WindowEntry>
<WindowEntry>
  <Name>tbwModel</Name>
  <View>TRN_MODEL</View>
  <LU>TrnModel</LU>
  <DefaultWindowText />
  <Flags>0</Flags>
</WindowEntry>
</WindowEntries>

​

​

Answer 1

仅供参考，代码应该是

using (XmlReader reader = XmlReader.Create("component.xml"))
{
    XmlDocument doc = new XmlDocument();
    doc.Load(reader);
    string path4 = treeView1.SelectedNode.FullPath.ToString();

    // now replace '\' by '/'
    path4 = path4.Replace('\\', '/');

    XmlNode nodeToRemove = doc.SelectSingleNode(path4);
    XmlNode parentNode = nodeToRemove.ParentNode;
    parentNode.RemoveChild(nodeToRemove);
}

1. 除非您仍在使用.NET 1.1，否则不要使用new XmlTextReader()。它已经被替换为XmlReader.Create().
2. You需要一个围绕阅读器的using块，以确保它被清理，而不管有什么异常。

Answer 2

正如Mark Hosang提到的，这是因为您使用的是\而不是/。尝试：

path4 = path4.Replace("\\", "/");

这应该会起作用;)

Answer 3

Xpath的格式必须正确: /node1/node2/.../nodeN

像这样修复，它是有效的:)

        XmlTextReader reader = new XmlTextReader("data.xml");
        XmlDocument doc = new XmlDocument();
        doc.Load(reader);
        string path4 = treeView1.SelectedNode.FullPath.ToString();       

        // now replace '\' by '/'
        path4 = path4.Replace('\\', '/');
        // appending '/' at beginning
        path4 = "/" + path4;           

        XmlNode nodeToRemove = doc.SelectSingleNode(path4);
        XmlNode parentNode = nodeToRemove.ParentNode;
        parentNode.RemoveChild(nodeToRemove);

请参考Xpath语法：http://www.w3schools.com/xpath/xpath_syntax.asp