From 4f1aa641d7325c2e85fcf608033e05084e18d917 Mon Sep 17 00:00:00 2001
From: leniency <levi.baker.101@gmail.com>
Date: Thu, 3 Feb 2022 18:45:30 -0800
Subject: [PATCH] Fix for the optimizer when an entity has a collection
 property that references itself.

Fixes #27301
# Conflicts:
#	src/EFCore.Design/Scaffolding/Internal/CSharpRuntimeModelCodeGenerator.cs
---
 .../CSharpRuntimeModelCodeGenerator.cs        |  2 +-
 .../CSharpRuntimeModelCodeGeneratorTest.cs    | 51 +++++++++++++++++++
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/src/EFCore.Design/Scaffolding/Internal/CSharpRuntimeModelCodeGenerator.cs b/src/EFCore.Design/Scaffolding/Internal/CSharpRuntimeModelCodeGenerator.cs
index 2e1a73e86f5..81356d1d5c4 100644
--- a/src/EFCore.Design/Scaffolding/Internal/CSharpRuntimeModelCodeGenerator.cs
+++ b/src/EFCore.Design/Scaffolding/Internal/CSharpRuntimeModelCodeGenerator.cs
@@ -1400,7 +1400,7 @@ private static void AddNamespace(Type type, ISet<string> namespaces)
             }
 
             var sequenceType = type.TryGetSequenceType();
-            if (sequenceType != null)
+            if (sequenceType != null && sequenceType != type)
             {
                 AddNamespace(sequenceType, namespaces);
             }
diff --git a/test/EFCore.Design.Tests/Scaffolding/Internal/CSharpRuntimeModelCodeGeneratorTest.cs b/test/EFCore.Design.Tests/Scaffolding/Internal/CSharpRuntimeModelCodeGeneratorTest.cs
index 0994a8bb75b..af66a4e5a16 100644
--- a/test/EFCore.Design.Tests/Scaffolding/Internal/CSharpRuntimeModelCodeGeneratorTest.cs
+++ b/test/EFCore.Design.Tests/Scaffolding/Internal/CSharpRuntimeModelCodeGeneratorTest.cs
@@ -56,6 +56,20 @@ namespace Microsoft.EntityFrameworkCore.Scaffolding.Internal
 {
     public class CSharpRuntimeModelCodeGeneratorTest
     {
+
+        [ConditionalFact]
+        public void Self_referential_property()
+            => Test(
+                new TestModel.Internal.SelfReferentialDbContext(),
+                new CompiledModelCodeGenerationOptions(),
+                assertModel: model =>
+                {
+                    Assert.Single(model.GetEntityTypes());
+                    Assert.Same(model, model.FindRuntimeAnnotationValue("ReadOnlyModel"));
+                }
+            );
+
+
         [ConditionalFact]
         public void Empty_model()
         {
@@ -3659,6 +3673,18 @@ public class IdentityUser : TestModels.AspNetIdentity.IdentityUser
     {
 
     }
+
+
+    public class SelfReferentialEntity
+    {
+        public long Id { get; set; }
+
+        public SelfReferentialProperty Collection { get; set; }
+    }
+
+    public class SelfReferentialProperty : List<SelfReferentialProperty>
+    {
+    }
 }
 
 namespace Microsoft.EntityFrameworkCore.Scaffolding.TestModel.Internal
@@ -3678,4 +3704,29 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
             modelBuilder.Entity<Scaffolding.Internal.Internal>();
         }
     }
+
+    public class SelfReferentialDbContext : ContextBase
+    {
+        protected override void OnModelCreating(ModelBuilder modelBuilder)
+        {
+            base.OnModelCreating(modelBuilder);
+
+            modelBuilder.Entity<Scaffolding.Internal.SelfReferentialEntity>(
+                eb =>
+                {
+                    eb.Property(e => e.Collection).HasConversion(typeof(SelfReferentialPropertyValueConverter));
+                });
+        }
+    }
+
+    public class SelfReferentialPropertyValueConverter : ValueConverter<Scaffolding.Internal.SelfReferentialProperty, string>
+    {
+        public SelfReferentialPropertyValueConverter()
+          : this(null)
+        { }
+
+        public SelfReferentialPropertyValueConverter(ConverterMappingHints hints)
+           : base(v => null, v => null, hints)
+        { }
+    }
 }