更新XML,获取“对象引用未设置为对象的实例”

时间:2016-03-21 16:15:46

标签: c# .net xml

我正在尝试更新XML文档中的3个数据,但是获取“对象引用未设置为对象的实例”错误。这是我想要更新的XML文件格式:

<?xml version="1.0" encoding="US-ASCII" standalone="true"?>
<ExportSettings xmlns="CompanyName" ExportName="Data Export" Dataset="TestName">
  <General>
     <AsOfDate>03/31/15</AsOfDate>
     <PriceDate>03/31/16</PriceDate>  
  </General>
  <Source>
      <Set>Set Name</Set>
  </Source>
</ExportSettings>

这是抛出错误的C#代码:

    private void btnUpdate_Click(object sender, EventArgs e)
    {
        try
        {
            {
                string strAsOfDate = dateTimePickerAsOfDate.Text;
                string strPriceDate = dateTimePickerPriceDate.Text;
                string strSetName = txtboxSet.Text;

                XmlDocument doc = new XmlDocument();
                doc.Load(strXMLfilepath);
                XmlNode General;
                XmlNode root = doc.DocumentElement;
                General = root.SelectSingleNode("/ExportSettings/General");
                General["AsOfDate"].InnerText = strAsOfDate;
                General["PriceDate"].InnerText = strPriceDate;
                XmlNode Source;
                Source = root.SelectSingleNode("/ExportSettings/Source");
                Source["Set"].InnerText = strSetName;
                doc.Save(strXMLfilepath);

            }
        }
        catch (System.Exception excep)
        {
            MessageBox.Show(excep.Message);
        }
    }

有人能看到问题吗?我对更新XML不太熟悉,所以这里可能存在一些基本错误。

1 个答案:

答案 0 :(得分:1)

我已在本地对其进行了调试,正如Pawel建议的那样,您需要对命名空间进行一些更改:

private void btnUpdate_Click(object sender, EventArgs e)
{
    try
    {
        {
            string strAsOfDate = dateTimePickerAsOfDate.Text;
            string strPriceDate = dateTimePickerPriceDate.Text;
            string strSetName = txtboxSet.Text;

            XmlDocument doc = new XmlDocument();
            doc.Load(strXMLfilepath);

            XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);
            nsmgr.AddNamespace("ab", "CompanyName");

            XmlNode General;
            XmlNode root = doc.DocumentElement;
            General = root.SelectSingleNode("//ab:General", nsmgr);
            General["AsOfDate"].InnerText = strAsOfDate;
            General["PriceDate"].InnerText = strPriceDate;

            doc.Save(strXMLfilepath);
        }
    }
    catch (System.Exception excep)
    {
        MessageBox.Show(excep.Message);
    }
}

希望这有帮助。