Mirror/doc/Articles/Guides/Sync/SyncDictionary.md

SyncDictionary

A SyncDictionary is an associative array containing an unordered list of key, value pairs. Keys and values can be of the following types:

• Basic type (byte, int, float, string, UInt64, etc)
• Built-in Unity math type (Vector3, Quaternion, etc)
• NetworkIdentity
• Game object with a NetworkIdentity component attached.
• Struct with any of the above

SyncDictionary works much like SyncLists: when you make a change on the server the change is propagated to all clients and the Callback is called.

To use it, create a class that derives from SyncDictionary for your specific type. This is necessary because the Weaver will add methods to that class. Then add a field to your NetworkBehaviour class.

Note that by the time you subscribe to the callback, the dictionary will already be initialized, so you will not get a call for the initial data, only updates.

Note SyncDictionaries must be initialized in the constructor, not in Startxxx(). You can make them readonly to ensure correct usage.

Simple Example

using UnityEngine;
using Mirror;

[System.Serializable]
public struct Item
{
    public string name;
    public int hitPoints;
    public int durability;
}

[System.Serializable]
public class SyncDictionaryStringItem : SyncDictionary<string, Item> {}

public class ExamplePlayer : NetworkBehaviour
{
    [SerializeField]
    public readonly SyncDictionaryStringItem Equipment = new SyncDictionaryStringItem();

    public override void OnStartServer()
    {
        Equipment.Add("head", new Item { name = "Helmet", hitPoints = 10, durability = 20 });
        Equipment.Add("body", new Item { name = "Epic Armor", hitPoints = 50, durability = 50 });
        Equipment.Add("feet", new Item { name = "Sneakers", hitPoints = 3, durability = 40 });
        Equipment.Add("hands", new Item { name = "Sword", hitPoints = 30, durability = 15 });
    }

    public override void OnStartClient()
    {
        // Equipment is already populated with anything the server set up
        // but we can subscribe to the callback in case it is updated later on
        Equipment.Callback += OnEquipmentChange;
    }

    void OnEquipmentChange(SyncDictionaryStringItem.Operation op, string key, Item item)
    {
        // equipment changed,  perhaps update the gameobject
        Debug.Log(op + " - " + key);
    }
}

By default, SyncDictionary uses a Dictionary to store it's data. If you want to use a different IDictionary implementation such as SortedList or SortedDictionary, add a constructor to your SyncDictionary implementation and pass a dictionary to the base class. For example:

[System.Serializable]
public class SyncDictionaryStringItem : SyncDictionary<string, Item> 
{
    public SyncDictionaryStringItem() : base (new SortedList<string,Item>()) {}
}
    
public class ExamplePlayer : NetworkBehaviour
{
    [SerializeField]
    public readonly SyncDictionaryStringItem Equipment = new SyncDictionaryStringItem();
}