Messagepack-csharp: Union with Generic Type

[neuecc]

Currently can not create this.

[Union(0, typeof(RemotableNotificationOnNext<>))]
[Union(1, typeof(RemotableNotificationOnError<>))]
[Union(2, typeof(RemotableNotificationOnCompleted<>))]
public interface IRemotableNotification<T>
{

}

[MessagePackObject]
public class RemotableNotificationOnNext<T> : IRemotableNotification<T>
{
    [Key(0)]
    public T Value { get; private set; }

    [SerializationConstructor]
    public RemotableNotificationOnNext(T value)
    {
        this.Value = value;
    }
}

[MessagePackObject]
public class RemotableNotificationOnError<T> : IRemotableNotification<T>
{
    [Key(0)]
    public string ErrorMessage { get; private set; }

    [SerializationConstructor]
    public RemotableNotificationOnError(string errorMessage)
    {
        this.ErrorMessage = errorMessage;
    }
}

[MessagePackObject]
public class RemotableNotificationOnCompleted<T> : IRemotableNotification<T>
{
}

[lgrabarevic]

Is there any chance this will be supported? I'm currently having the same issue.

[Weltengeist]

Yes, it would be amazing to get this work in the near future. We're struggeling with this issue for a while.

[github-actions[bot]]

This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[simonziegler]

Hi - this is going to be a major problem for me - can you please help? I have a class hierarchy requirement like this:

[MessagePack.MessagePackObject]
[MessagePack.Union(0, typeof(ClassB<>)]  // Note the requirement to register that ClassB is generic here
abstract class ClassA
{...}

[MessagePack.MessagePackObject]
[MessagePack.Union(0, typeof(ClassC)]
abstract class ClassB<T> : ClassA
{...}

[MessagePack.MessagePackObject]
class ClassC : ClassB<ClassD>
{...}

class ClassD
{...}

Can the unions for ClassA directly reference ClassC?

[AArnott]

We close inactive issues to allow us to better focus on high impact issues that impact a great number of folks. This hasn't shown up high on the list. If you'd like to offer to send a PR to fix it and include tests, we can reactivate and assign the issue to you.

[simonziegler]

@AArnott I worked out that this is what I need to do, and so have no requirement for a change to the current UnionAttribute:

[MessagePack.MessagePackObject]
[MessagePack.Union(0, typeof(ClassC)]  // Reference double inherited ClassC directly here!!!
abstract class ClassA
{...}

[MessagePack.MessagePackObject]
abstract class ClassB<T> : ClassA
{...}

[MessagePack.MessagePackObject]
class ClassC : ClassB<ClassD>
{...}

class ClassD
{...}

Many thanks for great library, Simon