向现有XML节点添加元素

Question

Where am i going wrong???

I have an xml file with OppDetails as a tag already as shown below

<OppDetails>
  <OMID>245414</OMID> 
  <ClientName>Best Buy</ClientName> 
  <OppName>International Rate Card</OppName> 
  <CTALinkType>AO,IO,MC,TC</CTALinkType> 
  </OppDetails>
  </OppFact>

Now i am trying to add another element to it but getting an error in AppendChild method please help

XmlNode rootNode = xmlDoc.SelectSingleNode("OppDetails");
XmlElement xmlEle = xmlDoc.CreateElement("CTAStartDate");
xmlEle.InnerText = ExcelUtility.GetCTAStartDate();
rootNode.AppendChild(xmlEle);
            xmlDoc.Save("C:\\test.xml");

Answer 1

XmlElement xmlEle = xmlDoc.DocumentElement["OppDetails"];
XmlElement eleNew = xmlDoc.CreateElement("CTAStartDate");
eleNew.InnerText = ExcelUtility.GetCTAStartDate();
xmlEle.AppendChild(eleNew);
xmlDoc.Save("C:\\test.xml");

Answer 2

It is hard to tell without a full sample, but a common reason for SelectNodes / SelectSingleNode returning null is xml namespaces. If you xml makes use of element namespaces, you'll probably need to use an XmlNamespaceManager along with your query, and define a suitable alias for the namespace you want.

Answer 3

Is rootNode null ?

From MSDN on SelectSingleNode :

The first XmlNode that matches the XPath query or a null reference (Nothing in Visual Basic) if no matching node is found.

If rootNode is null , it indicates that the node could not be found, and trying to use the null rootNode would cause the exception you are seeing.

Answer 4

The exception you've reported means that you have not located the root element. When SelectSingleNode can't find the requested node, it returns null . You didn't check for that.

Answer 5

Read root node and add the new element in to the root node. I think you are trying to append in XML document.