Question

我想更新xml节点并搜索网站以查找this link处的示例。但是，我得到的对象引用错误未设置为对象的实例。有人会告诉我如何获取节点。提前致谢

这是我的vb代码：

Imports System.Xml
Imports System.IO

Partial Class test2
Inherits System.Web.UI.Page


Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load      

    Dim xmlFileNamae As String = "Vancouver.xml"
    Dim xmlFilePath As String = ConfigurationManager.AppSettings("XMLFolder") & xmlFileNamae
    If File.Exists(xmlFilePath) Then
        Dim docXML As XmlDocument = New XmlDocument
        docXML.Load(xmlFilePath)
        Dim ID As String = "1"
        Dim node As XmlNode = docXML.SelectSingleNode("/Orders/Order[@ID='" & ID & "']/Date")
        node.InnerText = Date.Now
        node = docXML.SelectSingleNode("/Orders/Order[@ID='" & ID & "']/Country")
        node.InnerText = "Vancouver"
        docXML.Save(xmlFilePath)
    End If
End Sub

End Class

有我的xml文件：

<?xml version="1.0" encoding="utf-8"?>
  <Orders>
    <order ID="2">
      <item>Organ</item>
      <Date>7/24/2014 3:50:42 PM</Date>
      <Country>China</Country>
    </Order>
   <order ID="1">
     <item>Apple</item>
     <Date>7/24/2014 3:50:42 PM</Date>
     <Country>China</Country>
   </order>
</Orders>

Answer 1

首先，您的XML已损坏 - 您使用order关闭了第一个Order，这是错误的。

第二件事，你的XPath也不好。

以下是两个带有＆＃34;清洁工＆＃34;的XPath。代码。

    Dim XmlDoc As New XmlDocument
    Dim Node As XmlNode
    XmlDoc.Load(//Your path)
    //This will give you the date of the first order item in orders
    //where the ID attribute equals 1.
    Node = XmlDoc.SelectSingleNode("/Orders/order[@ID="1"]/Date")
    //Do somehintg
    //This will give you the country of the first order item in orders
    //where the ID attribute equals 1.
    Node=XmlDoc.SelectSingleNode("/Orders/order[@ID="1"]/Country")
    //Do something else.

无法获取特定的XML节点

1 个答案: