Unify behavior of adding and updating projected entities

src/SIL.Harmony.Sample/Changes/NewWordChange.cs

@@ -12,7 +12,8 @@ public class NewWordChange(Guid entityId, string text, string? note = null, Guid
 
     public override async ValueTask<Word> NewEntity(Commit commit, IChangeContext context)
     {
-        var antonymShouldBeNull = AntonymId is null || (await context.IsObjectDeleted(AntonymId.Value));
-        return (new Word { Text = Text, Note = Note, Id = EntityId, AntonymId = antonymShouldBeNull ? null : AntonymId });
+        var antonym = AntonymId is null ? null : await context.GetCurrent<Word>(AntonymId.Value);
+        antonym = antonym is { DeletedAt: null } ? antonym : null;
+        return new Word { Text = Text, Note = Note, Id = EntityId, Antonym = antonym, AntonymId = antonym?.Id };
     }
 }

src/SIL.Harmony.Sample/Changes/AddAntonymReferenceChange.cs → src/SIL.Harmony.Sample/Changes/SetAntonymReferenceChange.cs

@@ -4,18 +4,22 @@
 
 namespace SIL.Harmony.Sample.Changes;
 
-public class AddAntonymReferenceChange(Guid entityId, Guid antonymId)
-    : EditChange<Word>(entityId), ISelfNamedType<AddAntonymReferenceChange>
+public class SetAntonymReferenceChange(Guid entityId, Guid antonymId, bool setObject = true)
+    : EditChange<Word>(entityId), ISelfNamedType<SetAntonymReferenceChange>
 {
     public Guid AntonymId { get; set; } = antonymId;
+    public bool SetObject { get; set; } = setObject;
 
     public override async ValueTask ApplyChange(Word entity, IChangeContext context)
     {
         //if the word being referenced was deleted before this change was applied (could happen after a sync)
         //then we don't want to apply the change
         //if the change was already applied,
         //then this reference is removed via Word.RemoveReference after the change which deletes the Antonym, see SnapshotWorker.MarkDeleted
-        if (!await context.IsObjectDeleted(AntonymId))
-            entity.AntonymId = AntonymId;
+        var antonym = await context.GetCurrent<Word>(AntonymId);
+        if (antonym is null or { DeletedAt: not null }) return;
+
+        entity.Antonym = SetObject ? antonym : null;
+        entity.AntonymId = AntonymId;
     }
 }

src/SIL.Harmony.Sample/CrdtSampleKernel.cs

@@ -43,7 +43,7 @@ public static IServiceCollection AddCrdtDataSample(this IServiceCollection servi
                 .Add<EditExampleChange>()
                 .Add<SetWordTextChange>()
                 .Add<SetWordNoteChange>()
-                .Add<AddAntonymReferenceChange>()
+                .Add<SetAntonymReferenceChange>()
                 .Add<AddWordImageChange>()
                 .Add<SetOrderChange<Definition>>()
                 .Add<SetDefinitionPartOfSpeechChange>()
@@ -60,6 +60,10 @@ public static IServiceCollection AddCrdtDataSample(this IServiceCollection servi
                     builder.HasMany(w => w.Tags)
                         .WithMany()
                         .UsingEntity<WordTag>();
+                    builder.HasOne((w) => w.Antonym)
+                        .WithMany()
+                        .HasForeignKey(w => w.AntonymId)
+                        .OnDelete(DeleteBehavior.SetNull);
                 })
                 .Add<Definition>(builder =>
                 {
@@ -81,4 +85,4 @@ public static IServiceCollection AddCrdtDataSample(this IServiceCollection servi
         });
         return services;
     }
-}
+}

src/SIL.Harmony.Sample/Models/Word.cs

@@ -9,6 +9,7 @@ public class Word : IObjectBase<Word>
 
     public Guid Id { get; init; }
     public DateTimeOffset? DeletedAt { get; set; }
+    public Word? Antonym { get; set; }
     public Guid? AntonymId { get; set; }
     public Guid? ImageResourceId { get; set; }
     public List<Tag> Tags { get; set; } = new();
@@ -26,7 +27,11 @@ IEnumerable<Guid> Refs()
 
     public void RemoveReference(Guid id, CommitBase commit)
     {
-        if (AntonymId == id) AntonymId = null;
+        if (AntonymId == id)
+        {
+            AntonymId = null;
+            Antonym = null;
+        }
     }
 
     public IObjectBase Copy()
@@ -36,6 +41,7 @@ public IObjectBase Copy()
             Id = Id,
             Text = Text,
             Note = Note,
+            Antonym = Antonym,
             AntonymId = AntonymId,
             DeletedAt = DeletedAt,
             ImageResourceId = ImageResourceId,
@@ -46,7 +52,7 @@ public IObjectBase Copy()
     public override string ToString()
     {
         return
-            $"{nameof(Text)}: {Text}, {nameof(Id)}: {Id}, {nameof(Note)}: {Note}, {nameof(DeletedAt)}: {DeletedAt}, {nameof(AntonymId)}: {AntonymId}, {nameof(ImageResourceId)}: {ImageResourceId}" +
+            $"{nameof(Text)}: {Text}, {nameof(Id)}: {Id}, {nameof(Note)}: {Note}, {nameof(DeletedAt)}: {DeletedAt}, {nameof(Antonym)}: {Antonym}, {nameof(AntonymId)}: {AntonymId}, {nameof(ImageResourceId)}: {ImageResourceId}" +
             $", {nameof(Tags)}: {string.Join(", ", Tags.Select(t => t.Text))}";
     }
-}
+}