Question

I’m trying to serialize and deserialize this ObservableCollection:

public class DataCollection : ObservableCollection<Data>
{
}

public class Data : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private bool? _enabled;

    public string Name { get; set; }
    public bool? Enabled 
    {
        get { return _enabled; }
        set { _enabled = value; NotifyPropertyChanged("Enabled"); }
    }

    public Data(string name, bool? enabled)
    {
        this.ScriptName = name;
        this.Enabled = enabled;
    }

    private void NotifyPropertyChanged(string property)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(property));
    }
}

Using this class (as in the What is the easiest way to save an Observable collectin of object to an XML file? example):

class UserPreferences
{
    private DataCollection _dataLst;
    private const string _dataLstFileName = "Data.xml";

    public DataCollection DataLst { get { return _dataLst; } set { _dataLst = value; } }

    public UserPreferences()
    {
        Load();
    }

    public void Load()
    {
        if (File.Exists(_dataLstFileName))
        {
            using (var reader = new StreamReader(_dataLstFileName))
            {
                var xs = new XmlSerializer(typeof(DataCollection));
                _dataLst = (DataCollection) xs.Deserialize(reader);
            }
        }
        else
        {
            _dataLst = new DataCollection();
        }
    }

    public void Save()
    {
        using (var writer = new StreamWriter(_dataLstFileName))
        {
            var xs = new XmlSerializer(typeof(DataCollection));
            xs.Serialize(writer, _dataLst);
        }
    }
}

And here is how I call it from my app:

public partial class MainWindow : Window
{
    private DataCollection DataLst;

    ...

    private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
    {
        var userPrefs = new UserPreferences();

        userPrefs.DataLst = DataLst; // DataList isn't null and contains correct data
        userPrefs.Save(); 
    }
}

But it creates empty file and hangs up (even without exceptions, just app window becomes black and doesn’t response) in the line

var xs = new XmlSerializer(typeof(DataCollection));  

Answer 1

1. Your Data class must have a parameter less constructor, otherwise XmlSerializer will never be able to create instance of Data.
2. Instead of storing DataCoollection, you should store and retrieve Data[], it’s easier without having to do anything else.
3. While storing, you can call ToArray method to get Data[] and use typeof(Data[]) for serializer.
4. While reading you can read the array and add items into your collection.