C# Async serialization

Question

Is there a way to to serialize class asynchronously? I'm asking becouse when my program is trying to do this:

public static async void Serialize(List<Zajecia> xml_List)
    {
        using (var stream = await ApplicationData.Current.LocalFolder.OpenStreamForWriteAsync("Plan list.xml", CreationCollisionOption.ReplaceExisting))
        {
            XmlSerializer serializer = new XmlSerializer(typeof(List<Zajecia>));
            using (XmlWriter xmlWriter = XmlWriter.Create(stream, new XmlWriterSettings() { Indent = true }))
            {
                serializer.Serialize(xmlWriter, xml_List);
            }
        }

    }

Class:

public class Zajecia
    {
        public string c { get; set; }
        public string p { get; set; }

        public Zajecia ()
        {}
        public Zajecia(string C, string P)
        {
            c = C;
            p = P;
        }
    }

My async serialization is used in navigation function:

 protected override async Task OnNavigatedTo(NavigationEventArgs e)
    {
            string t = e.Parameter as string;

        if (!string.IsNullOrEmpty(t))
        {
            string[] _p = new string[10];
            _p = t.Split('^');
            _lista.Add(new Zajecia(t,( _p[3]+"("+_p[5]+")")));
            Dodaj_zajecia(_p);
            await Serialize(_lista);            
        }
        else
            base.OnNavigatedTo(e);

    }

I get only this error instead of serialization of anything:

System.Runtime.InteropServices.WindowsRuntime.RuntimeClass is inaccessible due to its protection level. Only public types can be processed.

Everything is public in my program and still it doesn't help. Any ideas how to make it work?

Answer 1

UPDATE 2

I have checked your project. The problem was, you declared Zajecia class within BasicPage1 class. You must declare it as separate class file or within scope of namespace.

Right Way

namespace Plan
{
    public class Zajecia
    {
     .....
    }

    public sealed partial class BasicPage1 : Plan.Common.LayoutAwarePage
    {
     .....
    }
}

Wrong Way

namespace Plan
{
    public sealed partial class BasicPage1 : Plan.Common.LayoutAwarePage
    {
        public class Zajecia
        {
         .....
        }
     .....
    }
}

---

UPDATE 1

Here's code for you.

public static async Task Serialize(List<Zajecia> xml_List)
{
    using (var stream = await ApplicationData.Current.LocalFolder.OpenStreamForWriteAsync("Plan list.xml", CreationCollisionOption.ReplaceExisting))
    {
        XmlSerializer serializer = new XmlSerializer(typeof(List<Zajecia>));
        using (XmlWriter xmlWriter = XmlWriter.Create(stream, new XmlWriterSettings() { Indent = true }))
        {
            serializer.Serialize(xmlWriter, xml_List);
        }
    }
}

Whenever you want to call the method use await as prefix, suppose any button click event calls that method then I will write like this.

Suppose Helper is my static class

private async void btnSerialize_Click(object sender, RoutedEventArgs e)
{
    await Helper.Serialize(MyZajeciaList);
}

Mark one thing I have used async void modifier in click event.

Suppose if I am calling method from any other method like DoWork(...), then I will use async Task instead of async void

private async Task DoWork(List<Zajecia> MyZajeciaList)
{
    await Helper.Serialize(MyZajeciaList);
}

---

Your code is working for me just change return type of Serialize method from void to Task. You need to call method as await Serialize(...);