From 070681888e9ae6aade4a0e6891eee5218a726d65 Mon Sep 17 00:00:00 2001
From: Gary Sharp <discoict@outlook.com>
Date: Thu, 4 Jul 2013 15:26:43 +1000
Subject: [PATCH] Update: Repository Monitor Deferred Actions

Defer code in 'before commit' to run 'after commit'
---
 .../Repository/Monitor/RepositoryMonitor.cs   |  7 ++++++
 .../Monitor/RepositoryMonitorEvent.cs         | 25 ++++++++++++++++---
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/Disco.Data/Repository/Monitor/RepositoryMonitor.cs b/Disco.Data/Repository/Monitor/RepositoryMonitor.cs
index e165f9bd..fdcd6ff7 100644
--- a/Disco.Data/Repository/Monitor/RepositoryMonitor.cs
+++ b/Disco.Data/Repository/Monitor/RepositoryMonitor.cs
@@ -74,11 +74,18 @@ namespace Disco.Data.Repository.Monitor
 
         internal static void UpdateAfterEventFromEntryState(RepositoryMonitorEvent monitorEvent)
         {
+            monitorEvent.afterCommit = true;
+
             if (monitorEvent.EventType == RepositoryMonitorEventType.Added)
             {
                 // Update Entity Key for Added Events
                 monitorEvent.EntityKey = DetermineEntityKey(monitorEvent.objectEntryState);
             }
+
+            // Execute Deferred Actions
+            if (monitorEvent.executeAfterCommit != null)
+                foreach (var deferredAction in monitorEvent.executeAfterCommit)
+                    deferredAction.Invoke(monitorEvent);
         }
 
         internal static RepositoryMonitorEvent EventFromEntryState(DiscoDataContext dbContext, DbEntityEntry entityEntry, ObjectStateEntry entryState)
diff --git a/Disco.Data/Repository/Monitor/RepositoryMonitorEvent.cs b/Disco.Data/Repository/Monitor/RepositoryMonitorEvent.cs
index 547d1338..467ff817 100644
--- a/Disco.Data/Repository/Monitor/RepositoryMonitorEvent.cs
+++ b/Disco.Data/Repository/Monitor/RepositoryMonitorEvent.cs
@@ -12,11 +12,13 @@ namespace Disco.Data.Repository.Monitor
     public class RepositoryMonitorEvent
     {
         [JsonIgnore]
-        internal ObjectStateEntry objectEntryState { get; set; }
+        internal ObjectStateEntry objectEntryState;
         [JsonIgnore]
-        internal DbEntityEntry dbEntityState { get; set; }
+        internal DbEntityEntry dbEntityState;
         [JsonIgnore]
-        internal bool afterCommit { get; set; }
+        internal bool afterCommit;
+        [JsonIgnore]
+        internal List<Action<RepositoryMonitorEvent>> executeAfterCommit;
 
         [JsonIgnore]
         public DiscoDataContext dbContext { get; set; }
@@ -44,7 +46,7 @@ namespace Disco.Data.Repository.Monitor
         public T GetPreviousPropertyValue<T>(string PropertyName)
         {
             if (afterCommit)
-                throw new InvalidOperationException("Unable to determine property values after repository commit");
+                throw new InvalidOperationException("Unable to determine property values after repository commit, use a deferred action instead");
             else
                 return (T)dbEntityState.OriginalValues[PropertyName];
         }
@@ -52,5 +54,20 @@ namespace Disco.Data.Repository.Monitor
         {
             return (T)dbEntityState.CurrentValues[PropertyName];
         }
+
+        public void ExecuteAfterCommit(Action<RepositoryMonitorEvent> action){
+            if (afterCommit)
+            {
+                // Execute Immediately
+                action.Invoke(this);
+            }
+            else
+            {
+                // Defer Execution
+                if (executeAfterCommit == null)
+                    executeAfterCommit = new List<Action<RepositoryMonitorEvent>>();
+                executeAfterCommit.Add(action);
+            }
+        }
     }
 }