Question

I’m using System.Xaml.XamlServices.Save method to serialize an object which has properties with public getters/private setters and by design these properties are ignored. I tried to implement advice of how to override default XAML bindings and get private properties serialized, but it doesn’t work for some reason – those properties are still ignored. Could anyone point out what’s wrong:

public class CustomXamlSchemaContext : XamlSchemaContext
{
    protected override XamlType GetXamlType(string xamlNamespace, string name, params XamlType[] typeArguments)
    {
        var type = base.GetXamlType(xamlNamespace, name, typeArguments);
        return new CustomXamlType(type.UnderlyingType, type.SchemaContext, type.Invoker);
    }
}

public class CustomXamlType : XamlType
{
    public CustomXamlType(Type underlyingType, XamlSchemaContext schemaContext, XamlTypeInvoker invoker) : base(underlyingType, schemaContext, invoker)
    {
    }

    protected override bool LookupIsConstructible()
    {
        return true;
    }

    protected override XamlMember LookupMember(string name, bool skipReadOnlyCheck)
    {
        var member = base.LookupMember(name, skipReadOnlyCheck);
        return new CustomXamlMember(member.Name, member.DeclaringType, member.IsAttachable);
    }
}

public class CustomXamlMember : XamlMember
{
    public CustomXamlMember(string name, XamlType declaringType, bool isAttachable) : base(name, declaringType, isAttachable)
    {
    }

    protected override bool LookupIsReadOnly()
    {
        return false;
    }
}


    public static string Save(object instance)
    {
        var stringWriter1 = new StringWriter(CultureInfo.CurrentCulture);
        var stringWriter2 = stringWriter1;
        var settings = new XmlWriterSettings { Indent = true, OmitXmlDeclaration = true };
        using (var writer = XmlWriter.Create(stringWriter2, settings))
        {
            Save(writer, instance);
        }
        return stringWriter1.ToString();
    }

    public static void Save(XmlWriter writer, object instance)
    {
        if (writer == null)
            throw new ArgumentNullException("writer");
        using (var xamlXmlWriter = new XamlXmlWriter(writer, new CustomXamlSchemaContext()))
        {
            XamlServices.Save(xamlXmlWriter, instance);
        }
    }

Having above infrastructure code and a class

public class Class1
{
    public string Property1 { get; private set; }
    public string Property2 { get; set; }
    public DateTime AddedProperty { get; set; }
}

and serializing an instance of this class with

var obj = new Class1 { Property1 = "value1", Property2 = "value2" };
var objString = Save(obj);

I get the result

<Class1 AddedProperty="0001-01-01" Property2="value2" xmlns="clr-namespace:TestNamespace;assembly=Tests" />

where there is no entry for Property1.

What’s even more interesting, that none of the overloads are called during serialization.

Answer 1

It turned out couple tweaks to my initial code solves the problem. Here’s final solution:

private class CustomXamlSchemaContext : XamlSchemaContext
{
    public override XamlType GetXamlType(Type type)
    {
        var xamlType = base.GetXamlType(type);
        return new CustomXamlType(xamlType.UnderlyingType, xamlType.SchemaContext, xamlType.Invoker);
    }
}

private class CustomXamlType : XamlType
{
    public CustomXamlType(Type underlyingType, XamlSchemaContext schemaContext, XamlTypeInvoker invoker)
        : base(underlyingType, schemaContext, invoker)
    {
    }

    protected override bool LookupIsConstructible()
    {
        return true;
    }

    protected override XamlMember LookupMember(string name, bool skipReadOnlyCheck)
    {
        var member = base.LookupMember(name, skipReadOnlyCheck);
        return member == null ? null : new CustomXamlMember((PropertyInfo)member.UnderlyingMember, SchemaContext, member.Invoker);
    }

    protected override IEnumerable<XamlMember> LookupAllMembers()
    {
        foreach (var member in base.LookupAllMembers())
        {
            var value = new CustomXamlMember((PropertyInfo)member.UnderlyingMember, SchemaContext, member.Invoker);
            yield return value;
        }
    }

    protected override bool LookupIsPublic()
    {
        return true;
    }
}

private class CustomXamlMember : XamlMember
{
    public CustomXamlMember(PropertyInfo propertyInfo, XamlSchemaContext schemaContext, XamlMemberInvoker invoker)
        : base(propertyInfo, schemaContext, invoker)
    {
    }

    protected override bool LookupIsReadOnly()
    {
        return false;
    }

    protected override bool LookupIsWritePublic()
    {
        return true;
    }
}

This customization allows to serialize/deserialize properties with public getter and public/internal/protected/private setters. It ignores all the other properties. It also serializes instances of internal classes.