SyncLists

SyncLists are array based lists similar to C# List that synchronize their contents from the server to the clients.

A SyncList can contain any supported mirror type.

Usage

SyncList must be declared readonly and initialized in the constructor.

Note that by the time you wire up the Action handlers, the list will already be initialized, so they will not get invoked for the initial data, only updates.

using UnityEngine;
using Mirror;

public class SyncListExample : NetworkBehaviour
{
    public readonly SyncList<string> namesList = new SyncList<string>();

    public override void OnStartClient()
    {
        // Add handlers for SyncList Actions
        namesList.OnAdd += OnItemAdded;
        namesList.OnInsert += OnItemInserted;
        namesList.OnSet += OnItemChanged;
        namesList.OnRemove += OnItemRemoved;
        namesList.OnClear += OnListCleared;

        // OnChange is a catch-all event that is called for any change
        // to the list. It is called after the specific events above.
        // Strongly recommended to use the specific events above instead!
        namesList.OnChange += OnListChanged;

        // List is populated before handlers are wired up so we
        // need to manually invoke OnAdd for each element.
        for (int i = 0; i < namesList.Count; i++)
            namesList.OnAdd.Invoke(i);
    }

    public override void OnStopClient()
    {
        // Remove handlers when client stops
        namesList.OnAdd -= OnItemAdded;
        namesList.OnInsert -= OnItemInserted;
        namesList.OnSet -= OnItemChanged;
        namesList.OnRemove -= OnItemRemoved;
        namesList.OnClear -= OnListCleared;
        namesList.OnChange -= OnListChanged;
    }

    void OnItemAdded(int index)
    {
        Debug.Log($"Element added at index {index} {namesList[index]}");
    }

    void OnItemInserted(int index)
    {
        Debug.Log($"Element inserted at index {index} {namesList[index]}");
    }

    void OnItemChanged(int index, string oldValue)
    {
        Debug.Log($"Element changed at index {index} from {oldValue} to {namesList[index]}");
    }

    void OnItemRemoved(int index, string oldValue)
    {
        Debug.Log($"Element removed at index {index} {oldValue}");
    }

    void OnListCleared()
    {
        // OnListCleared is called before the list is actually cleared
        // so we can iterate the list to get the elements if needed.
        foreach (string name in namesList)
            Debug.Log($"Element cleared {name}");
    }

    // OnListChanged is a catch-all event that is called for any change
    // to the list. It is called after the specific events above.
    //
    // NOTE: It's strongly recommended to use the specific events above instead!
    //
    // For OP_ADD and OP_INSERT, the value param is the NEW entry.
    // For OP_SET and OP_REMOVEAT, the value param is the OLD entry.
    // For OP_CLEAR, the param is null / default but you can iterate the list.
    void OnListChanged(SyncList<string>.Operation op, int index, string value)
    {
        switch (op)
        {
            case SyncList<string>.Operation.OP_ADD:
                // value is the NEW value of the entry
                Debug.Log($"Element added at index {index} {value}");
                break;

            case SyncList<string>.Operation.OP_INSERT:
                // value is the NEW value of the entry
                Debug.Log($"Element inserted at index {index} {value}");
                break;

            case SyncList<string>.Operation.OP_SET:
                // value is the OLD value of the entry
                Debug.Log($"Element changed at index {index} from {value} to {namesList[index]}");
                break;

            case SyncList<string>.Operation.OP_REMOVEAT:
                // value is the OLD value of the entry
                Debug.Log($"Element removed at index {index} was {value}");
                break;

            case SyncList<string>.Operation.OP_CLEAR:
                // value is null / default
                // we can iterate the list to get the elements if needed.
                foreach (string name in namesList)
                    Debug.Log($"Element cleared {name}");
                break;
        }
    }
}