Linq to XML orderby child element

Question

I have the following XML code:

<dsPreventieRegisterItem xmlns="http://tempuri.org/dsPreventieRegisterItem.xsd">
  <tblpreventieregisteritem>
    <DatumInterventie>2015-06-14</DatumInterventie>
    <TijdstipInterventie>11:30</TijdstipInterventie>
    <HulpverlenerNaam>Vandenbroucke</HulpverlenerNaam>
    <HulpverlenerVoornaam>Dirk</HulpverlenerVoornaam>
    <HulpbehoefteAard>Vinger en pols bezeerd </HulpbehoefteAard>
    <HulpbehoefteOorzaak>Ronddraaiende delen</HulpbehoefteOorzaak>
    <GebodenHulp>aanbrengen van Cold pack </GebodenHulp>
    <GebruikteMiddelen>Cold pack Ice spray Steunverband</GebruikteMiddelen>
    <Opmerkingen />
    <id>1</id>
  </tblPreventieRegisterItem>
</tblpreventieregisteritem>

But with multiple tblPreventieRegisterItem elements. This is declared in an XElement.

And then i want to put it in a IEnumerable<XElement> list. The problem i'm having is that the orderby never works.

IEnumerable <XElement> items =
        from el in root.Elements("tblpreventieregisteritem")
        orderby Int32.Parse(el.Element("id").Value) descending
        select el;

Anyone who has an idea?

Answer 1

This is a FAQ (Frequently Asked Question) in the XML topic. All elements in your XML are in default namespace which URI is "http://tempuri.org/dsPreventieRegisterItem.xsd" . You can use combination of XNamespace+ element's local-name to reference element in namespace, for example :

XNamespace d = "http://tempuri.org/dsPreventieRegisterItem.xsd";

IEnumerable <XElement> items =
        from el in root.Elements(d+"tblpreventieregisteritem")
        orderby (int)el.Element(d+"id") descending
        select el;

Notice that you can just cast XElement directly to int , which is a more concise and safer approach ie in case the XElement in question is not found.

---

working demo example :

var xml = @"<dsPreventieRegisterItem xmlns='http://tempuri.org/dsPreventieRegisterItem.xsd'>
  <tblpreventieregisteritem>
    <id>1</id>
  </tblpreventieregisteritem>
  <tblpreventieregisteritem>
    <id>2</id>
  </tblpreventieregisteritem>
  <tblpreventieregisteritem>
    <id>3</id>
  </tblpreventieregisteritem>
</dsPreventieRegisterItem> ";
var root = XElement.Parse(xml);
XNamespace d = "http://tempuri.org/dsPreventieRegisterItem.xsd";

IEnumerable<XElement> items =
    from el in root.Elements(d + "tblpreventieregisteritem")
    orderby (int)el.Element(d + "id") descending
    select el;

foreach (var item in items)
{
    Console.WriteLine(item.Element(d + "id").ToString());
}

output :

<id xmlns="http://tempuri.org/dsPreventieRegisterItem.xsd">3</id>
<id xmlns="http://tempuri.org/dsPreventieRegisterItem.xsd">2</id>
<id xmlns="http://tempuri.org/dsPreventieRegisterItem.xsd">1</id>

Answer 2

Have you tried this one:

        XNamespace ns = "http://tempuri.org/dsPreventieRegisterItem.xsd";

        IEnumerable<XElement> items =
        from rootElement in root.Elements("{" + ns + "}" + "dsPreventieRegisterItem")
        from el in rootElement.Elements("{" + ns + "}" + "tblpreventieregisteritem")
        orderby Int32.Parse(el.Element("{" + ns + "}" + "id").Value) descending
        select el;