Yoav Yoav - 16 days ago 7
C# Question

XElement.Decendents.First not finding xml field

I'm trying to read an XML file and find the value of a field.

I am reading from file "MyMessage.txt":

<?xml version="1.0" encoding="UTF-8"?>
<Document xmlns="urn:com.company:request.001">
<ReqHdr>
<AppInstanceId>AAAA</AppInstanceId>
</ReqHdr>
<ReqTxInf>
<PmtId>
<TxId>123456</TxId>
</PmtId>
<MsgTyp>REQUEST</MsgTyp>
</ReqTxInf>
</Document>


Here is the code:

// Read XElement from file
element = XElement.Parse(System.IO.File.ReadAllText(
System.IO.Path.Combine(
Environment.GetFolderPath(Environment.SpecialFolder.Desktop),
"MyMessage.txt")));
try
{
Console.WriteLine(element);
Console.WriteLine("TxId is:" + element.Descendants("TxId").First().Value);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
Console.WriteLine(e.StackTrace);
}


The file is read correctly and written to the console, but the search for TxId fails.

I tried to repeat this this time creating the file in code, and the same code finds TxId:

// Create XEleemnt in code
XNamespace ns = "urn:com.company:request.001";
XElement element = new XElement(ns + "Document",
new XElement("ReqHdr",
new XElement("AppInstanceId", "AAAA")),
new XElement("ReqTxInf",
new XElement("PmtId",
new XElement("TxId", "123456")),
new XElement("MsgTyp", "request")));

try
{
Console.WriteLine(element);
Console.WriteLine();
Console.WriteLine("TxId is:" + element.Descendants("TxId").First().Value);
Console.WriteLine();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
Console.WriteLine(e.StackTrace);
}

Answer

You're looking for an element called TxId in no namespace - but your element is implicitly in the "urn:com.company:request.001" namespace, which is inherited from its ancestor.

So you need:

element.Descendants(ns + "TxId").First()