feat: new virtual OnStopServer called when object is unspawned (#1743)

Assets/Mirror/Runtime/NetworkBehaviour.cs

@@ -840,6 +840,12 @@ public virtual void OnStopClient()
         /// </summary>
         public virtual void OnStartServer() { }
 
+        /// <summary>
+        /// Invoked on the server when the object is unspawned
+        /// <para>Useful for saving object data in persistant storage</para>
+        /// </summary>
+        public virtual void OnStopServer() { }
+
         /// <summary>
         /// Called on every NetworkBehaviour when it is activated on a client.
         /// <para>Objects on the host have this function called, as there is a local client on the host. The values of SyncVars on object are guaranteed to be initialized correctly with the latest state from the server when this function is called on the client.</para>

Assets/Mirror/Runtime/NetworkIdentity.cs

@@ -598,6 +598,26 @@ internal void OnStartServer()
             }
         }
 
+        internal void OnStopServer()
+        {
+            foreach (NetworkBehaviour comp in NetworkBehaviours)
+            {
+                // an exception in OnStartServer should be caught, so that one
+                // component's exception doesn't stop all other components from
+                // being initialized
+                // => this is what Unity does for Start() etc. too.
+                //    one exception doesn't stop all the other Start() calls!
+                try
+                {
+                    comp.OnStopServer();
+                }
+                catch (Exception e)
+                {
+                    Debug.LogError("Exception in OnStopServer:" + e.Message + " " + e.StackTrace);
+                }
+            }
+        }
+
         bool clientStarted;
         internal void OnStartClient()
         {

Assets/Mirror/Runtime/NetworkServer.cs

@@ -1094,6 +1094,8 @@ static void DestroyObject(NetworkIdentity identity, bool destroyServerObject)
                 identity.OnStopClient();
             }
 
+            identity.OnStopServer();
+
             // when unspawning, dont destroy the server's object
             if (destroyServerObject)
             {

Assets/Mirror/Tests/Editor/NetworkIdentityTests.cs

@@ -105,6 +105,22 @@ class NetworkDestroyCalledNetworkBehaviour : NetworkBehaviour
             public override void OnStopClient() { ++called; }
         }
 
+        class StopServerCalledNetworkBehaviour : NetworkBehaviour
+        {
+            public int called;
+            public override void OnStopServer() { ++called; }
+        }
+
+        class StopServerExceptionNetworkBehaviour : NetworkBehaviour
+        {
+            public int called;
+            public override void OnStopServer()
+            {
+                ++called;
+                throw new Exception("some exception");
+            }
+        }
+
         class SetHostVisibilityExceptionNetworkBehaviour : NetworkVisibility
         {
             public int called;
@@ -1038,6 +1054,38 @@ public void OnNetworkDestroy()
             Assert.That(comp.called, Is.EqualTo(1));
         }
 
+        [Test]
+        public void OnStopServer()
+        {
+            // add components
+            StopServerCalledNetworkBehaviour comp = gameObject.AddComponent<StopServerCalledNetworkBehaviour>();
+
+            // make sure our test values are set to 0
+            Assert.That(comp.called, Is.EqualTo(0));
+
+            identity.OnStopServer();
+            Assert.That(comp.called, Is.EqualTo(1));
+        }
+
+        [Test]
+        public void OnStopServerEx()
+        {
+            // add components
+            StopServerExceptionNetworkBehaviour compEx = gameObject.AddComponent<StopServerExceptionNetworkBehaviour>();
+
+            // make sure our test values are set to 0
+            Assert.That(compEx.called, Is.EqualTo(0));
+
+            // call OnNetworkDestroy in identity
+            // one component will throw an exception, but that shouldn't stop
+            // OnNetworkDestroy from being called in the second one
+            // exception will log an error
+            LogAssert.ignoreFailingMessages = true;
+            identity.OnStopServer();
+            LogAssert.ignoreFailingMessages = false;
+            Assert.That(compEx.called, Is.EqualTo(1));
+        }
+
         [Test]
         public void AddObserver()
         {