Saxon

Hello,

I am writing an application that will take complex types and use them as input into XQuery expressions. For this purpose, I am trying to pass an external variable into the XQueryEvaluator.

I didn't see a sample of this in the .NET samples, and the Java samples provided for this case use types that don't seem to be present in the .NET API.

Is it at all possible to do this using the .NET API?

A simple type I am trying to pass in as external variable:

public class Foo 
    {
        public int First { get; set; }
        public override string ToString()
        {
            return string.Format("First: {0}", First);
        }
    }

And this is the code I am using:

static void Main(string[] args)
        {
            Processor processor = new Processor();
            XQueryCompiler compiler = processor.NewXQueryCompiler();
            compiler.BaseUri = "file:///dummy/base/uri";
            compiler.ErrorList = new ArrayList();
            compiler.DeclareNamespace("spreadtrading", "http://saxon.sf.net/");
            XQueryExecutable exp = compiler.Compile("declare variable $payload external; {$payload}");
            XQueryEvaluator eval = exp.Load();
            
            var foo = new Foo{First = 7};
            var pv = XdmAtomicValue.WrapExternalObject(foo);
            eval.SetExternalVariable(new QName("payload"), pv);
            
            Serializer qout = new Serializer();
            qout.SetOutputProperty(Serializer.METHOD, "xml");
            qout.SetOutputProperty(Serializer.INDENT, "yes");
			qout.SetOutputStream(new FileStream("testoutput2.xml", FileMode.Create, FileAccess.Write));
            eval.Run(qout);
        }

When I run it, the line above: var pv = XdmAtomicValue.WrapExternalObject(foo); throws exception: Unable to cast object of type 'Saxon.Api.XdmValue' to type 'Saxon.Api.XdmAtomicValue'.

Considering the exception, I also tried two other things before posting here: 1) XdmValue.Wrap(Sequence foo) but I am unsure of how to convert my type to a Sequence, which seems to be an internal Saxon type.

new XdmValue(foo) with foo being a List, and type Foo inheriting from abstract class XdmItem But that throws a NPE during eval.Run(quot)

System Info Saxon version="9.7.0.15" .NET Framework 4.0