Non-nullable values in NetworkVariable<>

Hey guys, I'm having difficulties using my own struct in NetworkVariable<>. I've done everything as shown in INetworkSerializable documentation.

Code (CSharp):

1. public struct PData : INetworkSerializable
2. {
3.     int PlayerID;
4.     string PlayerName;
5.  
6.     public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter
7.     {
8.         serializer.SerializeValue(ref PlayerID);
9.         serializer.SerializeValue(ref PlayerName);
10.     }
11. }
12.  
13. public class PlayerData : NetworkBehaviour
14. {
15.  
16.     public NetworkVariable<PData> Data = new NetworkVariable<PData>();

Any ideas why VisualStudio returns:

"Error CS8377 The type 'PData' 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 'NetworkVariable<T>' Assembly-CSharp C:\UnityProj\hexmap\Assets\Scripts\PlayerData.cs 23 Active"

I noticed it works fine, if I remove any string variables from the struct and I delete serializer stuff. It's as if the serializer wasn't serializing anything?

 

It says everything in the struct must be non-nullable value type. A string is nullable.

 

Thank you for your reply. I see! I thought the serializing itself was going to make them non-nullable.

I just learned through youtube that Unity.Collections contains fixed size Strings, which can be used for this purpose

 

Wait so I want to use a string as a name and im getting a similar error, how exactly do i make a string "Non-nullable"?

 

Use "INetworkSerializeByMemcpy" instead of "INetworkSerializable", they canged it in 1.0.0-pre.8

 

Going off what itisMarcii_ said, you can create a "string wrapper" class

I copied this from the Boss Room project:

Code (CSharp):

1. /// <summary>
2. /// Wrapping FixedString so that if we want to change player name max size in the future, we only do it once here
3. /// </summary>
4. public struct FixedPlayerName : INetworkSerializable {
5.     ForceNetworkSerializeByMemcpy<FixedString32Bytes> m_Name; // using ForceNetworkSerializeByMemcpy to force compatibility between FixedString and NetworkSerializable
6.     public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter {
7.         serializer.SerializeValue(ref m_Name);
8.     }
9.  
10.     public override string ToString() {
11.         return m_Name.Value.ToString();
12.     }
13.  
14.     public static implicit operator string(FixedPlayerName s) => s.ToString();
15.     public static implicit operator FixedPlayerName(string s) => new FixedPlayerName() { m_Name = new FixedString32Bytes(s) };
16. }

Then you can use it like this:

Code (CSharp):

1.  
2. [System.Serializable]
3. public struct Player : INetworkSerializable, IEquatable<Player> {
4.     public FixedPlayerName name;
5.     public ulong clientId;
6.     ...
7. }

it will essentially act as a normal string because of the overloaded operators

 

Similarly i'm looking at adding a version for

List<int>

or

Dictionary<int, int>

since i want to send product IDs / count mapping and sync them between server-client. Not sure if this is the right approach but definitely feels easiest to track.