How to modify existing XML file with XmlDocument and XmlNode in C#

Question

I already implemented to create the XML file below with XmlTextWriter when application initialization.

And know I don't know how to update the childNode id value with XmlDocument & XmlNode.

Is there some property to update the id value? I tried InnerText but failed. thank you.

<?xml version="1.0" encoding="UTF-8"?> <Equipment xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">   <License licenseId="" licensePath=""/>   <DataCollections>     <GroupAIDs>       <AID id="100">         <Variable id="200"/>         <Variable id="201"/>       </AID>       <AID id="">         <Variable id="205"/>       </AID>       <AID id="102"/>     </GroupAIDs>     <GroupBIDs>       <BID id="2000">         <AID id="100"/>       </BID>       <BID id="2001">         <AID id="101"/>         <AID id="102"/>       </BID>     </GroupBIDs>     <GroupCIDs>       <BID id="8"/>       <BID id="9"/>       <BID id="10"/>     </GroupCIDs>   </DataCollections> </Equipment> 

Answer 1

You need to do something like this:

// instantiate XmlDocument and load XML from file XmlDocument doc = new XmlDocument(); doc.Load(@"D:\test.xml");  // get a list of nodes - in this case, I'm selecting all <AID> nodes under // the <GroupAIDs> node - change to suit your needs XmlNodeList aNodes = doc.SelectNodes("/Equipment/DataCollections/GroupAIDs/AID");  // loop through all AID nodes foreach (XmlNode aNode in aNodes) {    // grab the "id" attribute    XmlAttribute idAttribute = aNode.Attributes["id"];     // check if that attribute even exists...    if (idAttribute != null)    {       // if yes - read its current value       string currentValue = idAttribute.Value;        // here, you can now decide what to do - for demo purposes,       // I just set the ID value to a fixed value if it was empty before       if (string.IsNullOrEmpty(currentValue))       {          idAttribute.Value = "515";       }    } }  // save the XmlDocument back to disk doc.Save(@"D:\test2.xml");