chore: Fix onDelete behaviour for RelatedTransmissions (#949)

Missed this during the introduction of Transmissions

src/Digdir.Domain.Dialogporten.Domain/Dialogs/Entities/Transmissions/DialogTransmission.cs

@@ -16,18 +16,18 @@ public class DialogTransmission : IImmutableEntity
 
     public Uri? ExtendedType { get; set; }
 
-    public DialogTransmissionType.Values TypeId { get; set; }
-    public DialogTransmissionType Type { get; set; } = null!;
-
     // === Principal relationships ===
     public List<TransmissionContent> Content { get; set; } = [];
-
     public List<TransmissionAttachment> Attachments { get; set; } = [];
+    public List<DialogTransmission> RelatedTransmissions { get; set; } = [];
 
     // === Dependent relationships ===
     public Guid DialogId { get; set; }
     public DialogEntity Dialog { get; set; } = null!;
 
     public Guid? RelatedTransmissionId { get; set; }
     public DialogTransmission? RelatedTransmission { get; set; }
+
+    public DialogTransmissionType.Values TypeId { get; set; }
+    public DialogTransmissionType Type { get; set; } = null!;
 }

src/Digdir.Domain.Dialogporten.Infrastructure/Persistence/Configurations/Dialogs/Activities/DialogActivityConfiguration.cs

@@ -11,9 +11,5 @@ public void Configure(EntityTypeBuilder<DialogActivity> builder)
         builder.HasOne(x => x.RelatedActivity)
             .WithMany(x => x.RelatedActivities)
             .OnDelete(DeleteBehavior.SetNull);
-        // TODO: Rename in https://github.com/digdir/dialogporten/issues/860
-        // builder.HasOne(x => x.Transmission)
-        //     .WithMany(x => x.Activities)
-        //     .OnDelete(DeleteBehavior.SetNull);
     }
 }

src/Digdir.Domain.Dialogporten.Infrastructure/Persistence/Configurations/Dialogs/Transmissions/DialogTransmissionConfiguration.cs

@@ -0,0 +1,15 @@
+using Digdir.Domain.Dialogporten.Domain.Dialogs.Entities.Transmissions;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace Digdir.Domain.Dialogporten.Infrastructure.Persistence.Configurations.Dialogs.Transmissions;
+
+internal sealed class DialogTransmissionConfiguration : IEntityTypeConfiguration<DialogTransmission>
+{
+    public void Configure(EntityTypeBuilder<DialogTransmission> builder)
+    {
+        builder.HasOne(x => x.RelatedTransmission)
+            .WithMany(x => x.RelatedTransmissions)
+            .OnDelete(DeleteBehavior.SetNull);
+    }
+}