From b9ac7f2c4b1f49b310ea3615ad994fcfa308d72f Mon Sep 17 00:00:00 2001
From: Sipke Schoorstra <sipkeschoorstra@outlook.com>
Date: Wed, 12 Jul 2023 18:33:19 +0200
Subject: [PATCH] Harden Flowchart and Connection JSON serializers

---
 .../Flowchart/Serialization/ConnectionJsonConverter.cs    | 3 +++
 .../Flowchart/Serialization/FlowchartJsonConverter.cs     | 8 ++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/modules/Elsa.Workflows.Core/Activities/Flowchart/Serialization/ConnectionJsonConverter.cs b/src/modules/Elsa.Workflows.Core/Activities/Flowchart/Serialization/ConnectionJsonConverter.cs
index 66f831c21..4986405bf 100644
--- a/src/modules/Elsa.Workflows.Core/Activities/Flowchart/Serialization/ConnectionJsonConverter.cs
+++ b/src/modules/Elsa.Workflows.Core/Activities/Flowchart/Serialization/ConnectionJsonConverter.cs
@@ -44,6 +44,9 @@ public class ConnectionJsonConverter : JsonConverter<Connection>
     /// <inheritdoc />
     public override void Write(Utf8JsonWriter writer, Connection value, JsonSerializerOptions options)
     {
+        if (value.Source.Activity == null! || value.Target.Activity == null!)
+            return;
+        
         var model = new
         {
             Source = new
diff --git a/src/modules/Elsa.Workflows.Core/Activities/Flowchart/Serialization/FlowchartJsonConverter.cs b/src/modules/Elsa.Workflows.Core/Activities/Flowchart/Serialization/FlowchartJsonConverter.cs
index 23883865d..9f1b993b3 100644
--- a/src/modules/Elsa.Workflows.Core/Activities/Flowchart/Serialization/FlowchartJsonConverter.cs
+++ b/src/modules/Elsa.Workflows.Core/Activities/Flowchart/Serialization/FlowchartJsonConverter.cs
@@ -124,8 +124,12 @@ public class FlowchartJsonConverter : JsonConverter<Activities.Flowchart>
         {
             var missingSource = notFoundConnection.Source;
             var missingTarget = notFoundConnection.Target;
-            var source = foundActivities.FirstOrDefault(x => x.Id == missingSource.Activity.Id);
-            var target = foundActivities.FirstOrDefault(x => x.Id == missingTarget.Activity.Id);
+            
+            // ReSharper disable ConditionalAccessQualifierIsNonNullableAccordingToAPIContract
+            // Activity might be null in case of JSON missing information.
+            var source = foundActivities.FirstOrDefault(x => x.Id == missingSource.Activity?.Id); 
+            var target = foundActivities.FirstOrDefault(x => x.Id == missingTarget.Activity?.Id);
+            // ReSharper restore ConditionalAccessQualifierIsNonNullableAccordingToAPIContract
 
             if (source == null || target == null) continue;