Some time ago I asked a question about serializing a collection to a byte array and saving that. It resulting in this blog post.

I modified the Serialize and Deserialize functions to take a generic T type and I created collections which extend from ObservableCollection<t>. I uploaded a sample here.

protected override void OnInitialize()
{
    base.OnInitialize();

    if ((PersistentSegments != null) && (PersistentSegments.Length > 0))
    {
        _segmentCollection = Deserialize<Segment>(PersistentSegments) as NotifiableContinuousCollection<Segment>;
    }
    else
    {
        _segmentCollection = new NotifiableContinuousCollection<Segment>();
    }

    if (_segmentCollection != null)
    {
        _segmentCollection.CollectionChanged += OnCollectionChanged;
        _segmentCollection.CollectionItemChanged += OnCollectionItemChanged;
    }

    Session.Events.Persisting += OnPersisting;
}

private void OnPersisting(object sender, EventArgs e)
{
    if (HasChanged)
    {
        PersistentSegments = Serialize(_segmentCollection);
        HasChanged = false;
    }
}

I also have an add function which looks like this:

public void AddSegment(double distance, double value)
{
    _segmentCollection.Add(new Segment {Distance = distance, Value = value});
    Distance += distance;
}

Adding the first element is not a problem. When I add the second element I see that the Persisting event handler is called (I would have expected this to happen only when I'm actually calling .Save()) and it results in an exception:

SerializationContext is required. Use SerializationScope to set it.

What am I doing wrong here?

In the project I also included some extension methods: ToCollection() and ToByteArray(). If I use those the serialization works, but when I try to retrieve an item from the database on the second run of the program it throws an exception saying _segmentCollection.Count throw a NullReferenceException. The collection is correctly initialized as far as I can tell.