如何选择子节点，特别是xml节点？

Question

I want to delete selected row and update the xml file and then load the grid view with updated data. When debugging I get null value for nodelist.

This is my xml file

<?xml version="1.0" encoding="utf-8" ?>
<PERSONES>
  <person>
    <name>Dilan Perera</name>
    <age>22</age>
  </person>
  <person>
    <name>Thusitha Badde</name>
    <age>24</age>

  </person>
</PERSONES>

Here is the button click event. The problem is I get null value for nodelist

protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
{      
    GridViewRow row = (GridViewRow)GridView1.Rows[e.RowIndex];
    string age = row.Cells[2].Text.Trim(); // i get correct value for age here

    XmlDocument doc2 = new XmlDocument();
    doc2.Load(Server.MapPath("names.xml")); 
    XmlNode nodeList = doc2.SelectSingleNode(string.Format("PERSONES/person[@age='{0}']", age));

    doc2.DocumentElement.RemoveChild(nodeList);
    doc2.Save(Server.MapPath("names.xml"));

    getdata();   
}

Answer 1

The xpath query is incorrect, @ means attribute, so remove @ in the age check, then it will filter the element.

   protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
   {      
       GridViewRow row = (GridViewRow)GridView1.Rows[e.RowIndex];
       string age = row.Cells[2].Text.Trim(); // i get correct value for age here

       XmlDocument doc2 = new XmlDocument();
       doc2.Load(Server.MapPath("names.xml")); 
       XmlNode nodeList = doc2.SelectSingleNode(string.Format("PERSONES/person[age='{0}']", age));

       doc2.DocumentElement.RemoveChild(nodeList);
       doc2.Save(Server.MapPath("names.xml"));

       getdata();   
   }

I have just tested this and it works.

Answer 2

XmlDocument doc2 = new XmlDocument();
doc2.Load(Server.MapPath("names.xml")); 
XmlNode ageNode = doc2.SelectSingleNode(string.Format("//PERSONES/person/age[text() = '{0}']", age));
if (ageNode != null)
{
    var personNode = ageNode.ParentNode;

    doc2.DocumentElement.RemoveChild(personNode);
    doc2.Save(Server.MapPath("names.xml"));

}