Question

I am attempting to persist an object with a delegate property

public delegate void Callback(ScheduledTask ScheduledEvent);
public class ScheduledTask
    {
        [Key]
        public int Id { get; set; }

        /// <summary>
        /// Time the event will be triggered
        /// </summary>
        public DateTime ScheduledTime { get; set;} 


        /// <summary>
        /// Delegate to call back
        /// </summary>
        public Callback callback { get; set; }

        /// <summary>
        /// Any event metadata
        /// </summary>
        public Dictionary<String, object> Metadata { get; set; }
    }

However i receive this error:

(12,10) : error 3004: Problem in mapping fragments starting at lines 6, 12, 21:
No mapping specified for properties ScheduledTask.callback in Set ScheduledTasks.
An Entity with Key (PK) will not round-trip when:
Entity is type [Frontline.Core.Scheduling.ScheduledTask]

when loading the context.

How do i persist an object with a delegate using entity framework?

Answer 1

I ended up serialising it to a binary stream and saving that. Kind of gross, but its working.

    public byte[] callbackData { get; set; }

    /// <summary>
    /// Delegate to call back
    /// </summary>
    [NotMapped]
    public Callback callback
    {
        get
        {
            if (_callback == null && callbackData != null && callbackData.Count() > 0)
            {
                BinaryFormatter formatter = new BinaryFormatter();
                using (var stream = new MemoryStream(callbackData))
                {
                    _callback = formatter.Deserialize(stream) as Callback;
                }
            }
            return _callback;
        }
        set
        {
            _callback = value;
            if (value == null)
            {
                callbackData = null;
            }
            else
            {
                BinaryFormatter formatter = new BinaryFormatter();
                using (var stream = new MemoryStream())
                {
                    formatter.Serialize(stream, value);
                    callbackData = stream.ToArray();
                }
            }
        }
    }