Reducer event (#28)

* Deserializing reducer args before table updates so they can be accessed from callbacks

* Reducer arguments in table events

* Adding OnBeforeDelete event to tables

* Renaming ReducerCallInfo to ReducerEvent

* Removed extra onSubscriptionUpdate

---------

Co-authored-by: Steve <[email protected]>
Co-authored-by: John Detter <[email protected]>

Author: 3 people

sdks/csharp/Assets/SpacetimeDB/Scripts/ClientApiExtensions.cs

@@ -2,6 +2,6 @@
 {
     public partial class FunctionCall
     {
-        public SpacetimeDB.ReducerCallInfo CallInfo { get; internal set; }
+        public SpacetimeDB.ReducerEvent CallInfo { get; internal set; }
     }
 }

sdks/csharp/Assets/SpacetimeDB/Scripts/ClientCache.cs

@@ -55,6 +55,7 @@ public Type ClientTableType
             }
 
             public Action<object, ClientApi.Event> InsertCallback;
+            public Action<object, ClientApi.Event> BeforeDeleteCallback;
             public Action<object, ClientApi.Event> DeleteCallback;
             public Action<object, object, ClientApi.Event> UpdateCallback;
             // TODO: Consider renaming this one, this kind of implies that its a callback for the Update operation
@@ -79,6 +80,7 @@ public TableCache(Type clientTableType, AlgebraicType rowSchema, Func<AlgebraicV
                 this.rowSchema = rowSchema;
                 this.decoderFunc = decoderFunc;
                 InsertCallback = (Action<object, ClientApi.Event>)clientTableType.GetMethod("OnInsertEvent")?.CreateDelegate(typeof(Action<object, ClientApi.Event>));
+                BeforeDeleteCallback = (Action<object, ClientApi.Event>)clientTableType.GetMethod("OnBeforeDeleteEvent")?.CreateDelegate(typeof(Action<object, ClientApi.Event>));
                 DeleteCallback = (Action<object, ClientApi.Event>)clientTableType.GetMethod("OnDeleteEvent")?.CreateDelegate(typeof(Action<object, ClientApi.Event>));
                 UpdateCallback = (Action<object, object, ClientApi.Event>)clientTableType.GetMethod("OnUpdateEvent")?.CreateDelegate(typeof(Action<object, object, ClientApi.Event>));
                 RowUpdatedCallback = (Action<NetworkManager.TableOp, object, object, ClientApi.Event>)clientTableType.GetMethod("OnRowUpdateEvent")
@@ -185,6 +187,23 @@ public object DeleteEntry(byte[] rowPk)
                 return null;
             }
 
+            /// <summary>
+            /// Gets a value from the table
+            /// </summary>
+            /// <param name="rowPk">The primary key that uniquely identifies this row</param>
+            /// <returns></returns>
+            public bool TryGetValue(byte[] rowPk, out object value)
+            {
+                if (entries.TryGetValue(rowPk, out var v))
+                {
+                    value = v.Item2;
+                    return true;
+                }
+
+                value = null;
+                return false;
+            }
+
             public bool ComparePrimaryKey(AlgebraicValue v1, AlgebraicValue v2)
             {
                 return (bool)ComparePrimaryKeyFunc.Invoke(rowSchema, v1, v2);

sdks/csharp/Assets/SpacetimeDB/Scripts/NetworkManager.cs

@@ -157,13 +157,13 @@ protected void Awake()
             // cache all our reducer events by their function name 
             foreach (var methodInfo in typeof(SpacetimeDB.Reducer).GetMethods())
             {
-                if (methodInfo.GetCustomAttribute<ReducerEvent>() is
+                if (methodInfo.GetCustomAttribute<ReducerCallbackAttribute>() is
                     { } reducerEvent)
                 {
                     reducerEventCache.Add(reducerEvent.FunctionName, (Action<ClientApi.Event>)methodInfo.CreateDelegate(typeof(Action<ClientApi.Event>)));
                 }
 
-                if (methodInfo.GetCustomAttribute<DeserializeEvent>() is
+                if (methodInfo.GetCustomAttribute<DeserializeEventAttribute>() is
                     { } deserializeEvent)
                 {
                     deserializeEventCache.Add(deserializeEvent.FunctionName, (Action<ClientApi.Event>)methodInfo.CreateDelegate(typeof(Action<ClientApi.Event>)));
@@ -420,7 +420,25 @@ private void OnMessageProcessComplete(Message message, IList<DbEvent> events)
             {
                 case Message.TypeOneofCase.SubscriptionUpdate:
                 case Message.TypeOneofCase.TransactionUpdate:
-                    // First apply all of the state
+                    // First trigger OnBeforeDelete
+                    for (var i = 0; i < events.Count; i++)
+                    {
+                        // TODO: Reimplement updates when we add support for primary keys
+                        var ev = events[i];
+                        if (ev.op == TableOp.Delete && ev.table.TryGetValue(ev.deletedPk, out var oldVal))
+                        {
+                            try
+                            {
+                                ev.table.BeforeDeleteCallback?.Invoke(oldVal, message.Event);
+                            }
+                            catch (Exception e)
+                            {
+                                Debug.LogException(e);
+                            }
+                        }
+                    }
+
+                    // Apply all of the state
                     for (var i = 0; i < events.Count; i++)
                     {
                         // TODO: Reimplement updates when we add support for primary keys

sdks/csharp/Assets/SpacetimeDB/Scripts/ReducerExtensions.cs

@@ -2,12 +2,12 @@
 
 namespace SpacetimeDB
 {
-    public class ReducerEvent : Attribute
+    public class ReducerCallbackAttribute : Attribute
     {
         public string FunctionName { get; set; }
     }
 
-    public class DeserializeEvent : Attribute
+    public class DeserializeEventAttribute : Attribute
     {
         public string FunctionName { get; set; }
     }

sdks/csharp/Assets/SpacetimeDB/Scripts/Stubs.cs

@@ -8,8 +8,7 @@ public partial class Reducer
     {
     }
 
-    public partial class ReducerCallInfo
+    public partial class ReducerEvent
     {
-        public SpacetimeDB.NetworkManager.DbEvent[] RowChanges { get; internal set; }
     }
 }