NetworkList<T> initialization and Docs: /versioned_docs/version-1.0.0/advanced-topics/serialization/inetworkserializable.md

[Falkonio]

I can not initialize NetworkList.

using Unity.Netcode;

    public struct LobbyPlayerState : INetworkSerializable
    {
        public ulong ClientId;
        public string PlayerName;
        public bool IsReady;

        public LobbyPlayerState(ulong clientId, string playerName, bool isReady)
        {
            ClientId = clientId;
            PlayerName = playerName;
            IsReady = isReady;
        }

        public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter
        {
            serializer.SerializeValue(ref ClientId);
            serializer.SerializeValue(ref PlayerName);
            serializer.SerializeValue(ref IsReady);
        }
    }

Next I try initialize NetworkList type of LobbyPlayerState:

public class Lobby : NetworkBehaviour
{
      private NetworkList<LobbyPlayerState> lobbyPlayers = new NetworkList<LobbyPlayerState>();
}

And get error:

Severity Code Description Project File Line Suppression State
Error CS8377 The type 'LobbyPlayerState' must be a non-nullable value type, along with all fields at any level of nesting, in order to use it as parameter 'T' in the generic type or method 'NetworkList'

How can I fix this error and initialize the NetworkList for further use? The instructions lack a more detailed disclosure of this point.

[LukeStampfli]

Transferred this to this repository since it seems to be a NetworkList bug?

[LukeStampfli]

This is by design, NetworkList only supports structs which are unmanaged. String is a managed type so it cannot be part of a struct used in a NetworkList. You can use FixedString64 instead of a String.

[Falkonio]

FixedString64 renamed to FixedString64Bytes. If I use FixedString64Bytes or FixedString32Bytes I get error:

Error	CS0315	The type 'LobbyPlayerState' cannot be used as type parameter 'T' in the generic type or method 'NetworkList<T>'. There is no boxing conversion from 'LobbyPlayerState' to 'System.IEquatable<LobbyPlayerState>'.

[davidyrgilbert]

Had the same issue, I think also implementing IEquatable seems to fix that error, or at least makes it not show up anymore. Have not actually tested the functionality.

 public struct RemoteFileSourceInformation : INetworkSerializable, IEquatable<RemoteFileSourceInformation>
    {
        public int SourceId;
        public FixedString32Bytes FilePath;
        public FixedString32Bytes SourceName;

        public RemoteFileSourceInformation(int sourceId, FixedString32Bytes filePath, FixedString32Bytes sourceName)
        {
            SourceId = sourceId;
            FilePath = filePath;
            SourceName = sourceName;
        }
        
        // INetworkSerializable
        public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter
        {
            serializer.SerializeValue(ref SourceId);
            serializer.SerializeValue(ref FilePath);
            serializer.SerializeValue(ref SourceName);
        }
        // ~INetworkSerializable
        
        // IEquatable
        public bool Equals(RemoteFileSourceInformation other)
        {
            return SourceId == other.SourceId && FilePath.Equals(other.FilePath) && SourceName.Equals(other.SourceName);
        }

        // public override bool Equals(object obj)
        // {
        //     return obj is RemoteFileSourceInformation other && Equals(other);
        // }
        //
        // public override int GetHashCode()
        // {
        //     return HashCode.Combine(SourceId, FilePath, SourceName);
        // }
        
        // ~IEquatable
    }

If that's the correct way to do it, this should be in the docs too.

[LukeStampfli]

Yes implemententing IEquatable is necessary for NetworkList and your implementation looks correct. You currently have the GetHashCode and Equals function commented out, I'd recommend to override them like you did instead of using the default struct equality functions.

As for adding this to the docs, could you open an issue in the docs repo?