Need Help for writing an XML Start Element in C# using xmltextWriter

Question

I write code like this

  XmlDocument xdocMulticom = new XmlDocument();
  StringWriter strwMultiXml = new StringWriter();
  XmlTextWriter xmlMultiAirInfo = new XmlTextWriter(strwMultiXml);
  xmlMultiAirInfo.Formatting = Formatting.None;

  xmlMultiAirInfo.WriteStartDocument();
  xmlMultiAirInfo.WriteStartElement("ns", "cancelreservation", "http://www.opentravel.org/ota/2003/05");
  xmlMultiAirInfo.WriteStartElement("OTA_VehCancelRQ");
  xmlMultiAirInfo.WriteAttributeString("xmlns", "http://www.opentravel.org/ota/2003/05");
  xmlMultiAirInfo.WriteAttributeString("xmlns", "xsi", null, "http://www.w3.org/2001/XMLSchema-instance");
  xmlMultiAirInfo.WriteAttributeString("Version", "1.002");
  xmlMultiAirInfo.WriteAttributeString("PrimaryLangID", "EN");
  xmlMultiAirInfo.WriteAttributeString("ReqRespVersion", "2.001");
  xmlMultiAirInfo.WriteStartElement("POS");
  xmlMultiAirInfo.WriteStartElement("Source");
  xmlMultiAirInfo.WriteStartElement("RequestorID");
  xmlMultiAirInfo.WriteAttributeString("Type", "4");
  xmlMultiAirInfo.WriteAttributeString("ID", "F0F4CCE4A9C24355");
  xmlMultiAirInfo.WriteEndElement();
  xmlMultiAirInfo.WriteEndElement();
  xmlMultiAirInfo.WriteEndElement();
  xmlMultiAirInfo.WriteStartElement("VehCancelRQCore");
  xmlMultiAirInfo.WriteAttributeString("CancelType", "Cancel");
  xmlMultiAirInfo.WriteStartElement("UniqueID");
  xmlMultiAirInfo.WriteAttributeString("Type", "14");
  xmlMultiAirInfo.WriteAttributeString("ID", "N2169641");
  xmlMultiAirInfo.WriteStartElement("PersonName");
  xmlMultiAirInfo.WriteElementString("GivenName", "Sandra");
  xmlMultiAirInfo.WriteElementString("Surname", "Jhonsan");
  xmlMultiAirInfo.WriteEndElement();
  xmlMultiAirInfo.WriteEndElement();                         
  xmlMultiAirInfo.WriteEndElement();
  xmlMultiAirInfo.WriteStartElement("VehCancelRQInfo");
  xmlMultiAirInfo.WriteStartElement("Vendor");
  xmlMultiAirInfo.WriteAttributeString("Code", "ZR");
  xmlMultiAirInfo.WriteEndElement();                          
  xmlMultiAirInfo.WriteEndElement();
  xmlMultiAirInfo.WriteEndElement();
  xmlMultiAirInfo.WriteEndElement();
  xdocMulticom.LoadXml(strwMultiXml.ToString());

which generates output like this:

<?xml version="1.0" encoding="utf-16"?>
<ns:cancelreservation xmlns:ns="http://www.opentravel.org/ota/2003/05">
  <OTA_VehCancelRQ xmlns="http://www.opentravel.org/ota/2003/05" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" Version="1.002" PrimaryLangID="EN" ReqRespVersion="2.001">
    <POS>
      <Source>
        <RequestorID Type="4" ID="F0F4CCE4A9C24355" />
      </Source>
    </POS>
    <VehCancelRQCore CancelType="Cancel">
      <UniqueID Type="14" ID="N2169641">
        <PersonName>
          <GivenName>Sandra</GivenName>
          <Surname>Jhonsan</Surname>
        </PersonName>
      </UniqueID>
    </VehCancelRQCore>
    <VehCancelRQInfo>
      <Vendor Code="ZR" />
    </VehCancelRQInfo>
  </OTA_VehCancelRQ>
</ns:cancelreservation>

Which is ok to me but i need it to be like this:

<?xml version="1.0" encoding="utf-16"?>
<ns:cancelreservation>
  <OTA_VehCancelRQ xmlns="http://www.opentravel.org/ota/2003/05" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" Version="1.002" PrimaryLangID="EN" ReqRespVersion="2.001">
    <POS>
      <Source>
        <RequestorID Type="4" ID="F0F4CCE4A9C24355" />
      </Source>
    </POS>
    <VehCancelRQCore CancelType="Cancel">
      <UniqueID Type="14" ID="N2169641">
        <PersonName>
          <GivenName>Sandra</GivenName>
          <Surname>Jhonsan</Surname>
        </PersonName>
      </UniqueID>
    </VehCancelRQCore>
    <VehCancelRQInfo>
      <Vendor Code="ZR" />
    </VehCancelRQInfo>
  </OTA_VehCancelRQ>
</ns:cancelreservation>

Is there any way to change it?

Answer 1

As I See, difference only in namespace in first node... (or it's my mistake?)

Replace this line:

xmlMultiAirInfo.WriteStartElement("ns", "cancelreservation", "http://www.opentravel.org/ota/2003/05");

with this.

xmlMultiAirInfo.WriteStartElement("ns", "cancelreservation", "");

Well, C# is doing all right. Because your element doesn't know about such prefix. In your sample, "cancelreservation" is not the root element, but if it will be root, xmlns attribute must be present.