From ed4eeee647830c11e3f12b4670f344aae2c943c4 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Tue, 27 Apr 2021 10:14:19 +0200
Subject: [PATCH] Fix undo for custom serialized objects (eg. LocalizedString)

---
 Source/Editor/History/UndoActionObject.cs     | 22 +++++++++++++++++++
 Source/Editor/SceneGraph/SceneGraphNode.cs    |  1 +
 Source/Editor/Undo/UndoActionBase.cs          | 16 +++-----------
 Source/Engine/Serialization/JsonConverters.cs |  7 ++++++
 4 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/Source/Editor/History/UndoActionObject.cs b/Source/Editor/History/UndoActionObject.cs
index cac710bff..a87637f4f 100644
--- a/Source/Editor/History/UndoActionObject.cs
+++ b/Source/Editor/History/UndoActionObject.cs
@@ -4,6 +4,8 @@ using System;
 using System.Collections.Generic;
 using FlaxEditor.Utilities;
 using FlaxEngine;
+using Newtonsoft.Json;
+using JsonSerializer = FlaxEngine.Json.JsonSerializer;
 
 namespace FlaxEditor.History
 {
@@ -114,6 +116,8 @@ namespace FlaxEditor.History
             public object TargetInstance;
         }
 
+        internal static JsonSerializerSettings JsonSettings;
+
         // For objects that cannot be referenced in undo action like: FlaxEngine.Object or SceneGraphNode we store them in DataStorage,
         // otherwise here:
         private readonly object TargetInstance;
@@ -177,6 +181,24 @@ namespace FlaxEditor.History
             };
         }
 
+        /// <inheritdoc />
+        public override DataStorage Data
+        {
+            protected set
+            {
+                // Inject objects typename serialization to prevent data type mismatch when loading from saved state
+                var settings = JsonSettings;
+                if (settings == null)
+                {
+                    settings = JsonSerializer.CreateDefaultSettings(false);
+                    settings.TypeNameHandling = TypeNameHandling.All;
+                    JsonSettings = settings;
+                }
+                _data = JsonConvert.SerializeObject(value, Formatting.Indented, settings);
+                //Editor.Log(_data);
+            }
+        }
+
         /// <inheritdoc />
         public override string ActionString { get; }
 
diff --git a/Source/Editor/SceneGraph/SceneGraphNode.cs b/Source/Editor/SceneGraph/SceneGraphNode.cs
index 76327918d..6cf83647a 100644
--- a/Source/Editor/SceneGraph/SceneGraphNode.cs
+++ b/Source/Editor/SceneGraph/SceneGraphNode.cs
@@ -374,6 +374,7 @@ namespace FlaxEditor.SceneGraph
         /// <summary>
         /// Gets or sets the node state.
         /// </summary>
+        [NoSerialize]
         public virtual StateData State
         {
             get => throw new NotImplementedException();
diff --git a/Source/Editor/Undo/UndoActionBase.cs b/Source/Editor/Undo/UndoActionBase.cs
index 5de052a45..6648096c6 100644
--- a/Source/Editor/Undo/UndoActionBase.cs
+++ b/Source/Editor/Undo/UndoActionBase.cs
@@ -4,7 +4,6 @@ using System;
 using FlaxEditor.SceneGraph;
 using FlaxEngine;
 using Newtonsoft.Json;
-using JsonSerializer = FlaxEngine.Json.JsonSerializer;
 
 namespace FlaxEditor
 {
@@ -28,7 +27,6 @@ namespace FlaxEditor
                 var id = Guid.Parse((string)reader.Value);
                 return SceneGraphFactory.FindNode(id);
             }
-
             return null;
         }
 
@@ -56,19 +54,11 @@ namespace FlaxEditor
         /// <summary>
         /// Gets or sets the serialized undo data.
         /// </summary>
-        /// <value>
-        /// The data.
-        /// </value>
         [NoSerialize]
-        public TData Data
+        public virtual TData Data
         {
-            get => JsonConvert.DeserializeObject<TData>(_data, JsonSerializer.Settings);
-            protected set => _data = JsonConvert.SerializeObject(value, Formatting.None, JsonSerializer.Settings);
-            /*protected set
-            {
-                _data = JsonConvert.SerializeObject(value, Formatting.Indented, JsonSerializer.Settings);
-                Debug.Info(_data);
-            }*/
+            get => JsonConvert.DeserializeObject<TData>(_data, FlaxEngine.Json.JsonSerializer.Settings);
+            protected set => _data = JsonConvert.SerializeObject(value, Formatting.None, FlaxEngine.Json.JsonSerializer.Settings);
         }
 
         /// <inheritdoc />
diff --git a/Source/Engine/Serialization/JsonConverters.cs b/Source/Engine/Serialization/JsonConverters.cs
index 4403487a0..2ebf16a79 100644
--- a/Source/Engine/Serialization/JsonConverters.cs
+++ b/Source/Engine/Serialization/JsonConverters.cs
@@ -236,6 +236,13 @@ namespace FlaxEngine.Json
             else
             {
                 writer.WriteStartObject();
+#if FLAX_EDITOR
+                if ((serializer.TypeNameHandling & TypeNameHandling.Objects) == TypeNameHandling.Objects)
+                {
+                    writer.WritePropertyName("$type");
+                    writer.WriteValue("FlaxEngine.LocalizedString, FlaxEngine.CSharp");
+                }
+#endif
                 writer.WritePropertyName("Id");
                 writer.WriteValue(str.Id);
                 writer.WritePropertyName("Value");