Fix off-screen row updates in the Library

src/Abstractions/NexusMods.Abstractions.MnemonicDB.Attributes/Extensions/EntityExtensions.cs

@@ -10,29 +10,29 @@ namespace NexusMods.Abstractions.MnemonicDB.Attributes.Extensions;
 /// </summary>
 public static class EntityExtensions
 {
-
     /// <summary>
     /// Gets the largest transaction id in the model.
     /// </summary>
     public static TxId MostRecentTxId(this IReadOnlyModel model)
     {
         return model.Max(m => m.T);
     }
-
-
+
     /// <summary>
     /// Gets the timestamp of the transaction that created the model.
     /// </summary>
     /// <param name="model"></param>
+    /// <param name="dateTime">A default value to return if the model doesn't exist.</param>
     /// <returns></returns>
-    public static DateTime GetCreatedAt<T>(this T model)
+    public static DateTime GetCreatedAt<T>(this T model, DateTime? dateTime = null)
     where T : IReadOnlyModel
     {
+        if (model.Count == 0)
+            return dateTime ?? DateTime.MinValue;
         var tx = new Transaction.ReadOnly(model.Db, EntityId.From(model.Min(m => m.T).Value));
         return Transaction.Timestamp.Get(tx);
     }
 
-
     /// <summary>
     /// Tries to parse an entity id from a hex string.
     /// </summary>

src/NexusMods.App.UI/Controls/TreeDataGrid/TreeDataGridAdapter.cs

@@ -54,7 +54,7 @@ protected TreeDataGridAdapter()
                 .AddTo(disposables);
 
             self.Roots
-                .ObserveCountChanged()
+                .ObserveCountChanged(notifyCurrentCount: true)
                 .Subscribe(self, static (count, self) => self.IsSourceEmpty.Value = count == 0)
                 .AddTo(disposables);
 

src/NexusMods.App.UI/Pages/LibraryPage/FakeParentLibraryItemModel.cs

@@ -33,7 +33,7 @@ public FakeParentLibraryItemModel(LibraryItemId libraryItemId, IObservable<IChan
             model.NumInstalledObservable
                 .ToObservable()
                 .CombineLatest(
-                    source2: model.LibraryItems.ObserveCountChanged(),
+                    source2: model.LibraryItems.ObserveCountChanged(notifyCurrentCount: true),
                     source3: model.WhenAnyValue(static model => model.IsExpanded).ToObservable(),
                     source4: model.IsInstalledInLoadout,
                     static (a,b,c , _) => (a,b,c)

src/NexusMods.App.UI/Pages/LibraryPage/LibraryItemModel.cs

@@ -54,6 +54,7 @@ public LibraryItemModel(LibraryItemId libraryItemId)
 
         _modelActivationDisposable = WhenModelActivated(this, static (model, disposables) =>
         {
+
             Debug.Assert(model.Ticker is not null, "should've been set before activation");
             model.Ticker.Subscribe(model, static (now, model) =>
             {
@@ -62,31 +63,38 @@ public LibraryItemModel(LibraryItemId libraryItemId)
             }).AddTo(disposables);
 
             model.LinkedLoadoutItems
-                .ObserveCountChanged()
+                // Observe Count Changed defaults to not notifying the current count on a new subscription
+                // Because this chain will be destroyed when the model is deactivated, we want to know the current count
+                // when we reactivate a gain. Rows in a TreeDataGrid are virtualized and so they will be repeatedly activated and deactivated
+                .ObserveCountChanged(notifyCurrentCount: true)
                 .Subscribe(model, static (count, model) =>
-                {
-                    if (count > 0)
                     {
-                        model.InstallText.Value = "Installed";
-                        model.IsInstalledInLoadout.Value = true;
-                        model.InstalledDate.Value = model.LinkedLoadoutItems.Select(static kv => kv.Value.GetCreatedAt()).Max();
-                        model.FormattedInstalledDate.Value = FormatDate(DateTime.Now, model.InstalledDate.Value);
+                        if (count > 0)
+                        {
+                            model.InstallText.Value = "Installed";
+                            model.IsInstalledInLoadout.Value = true;
+                            model.InstalledDate.Value = model.LinkedLoadoutItems.Select(static kv => kv.Value.GetCreatedAt()).Max();
+                            model.FormattedInstalledDate.Value = FormatDate(DateTime.Now, model.InstalledDate.Value);
+                        }
+                        else
+                        {
+                            model.InstallText.Value = "Install";
+                            model.IsInstalledInLoadout.Value = false;
+                            model.InstalledDate.Value = DateTime.UnixEpoch;
+                            model.FormattedInstalledDate.Value = "-";
+                        }
                     }
-                    else
-                    {
-                        model.InstallText.Value = "Install";
-                        model.IsInstalledInLoadout.Value = false;
-                        model.InstalledDate.Value = DateTime.UnixEpoch;
-                        model.FormattedInstalledDate.Value = "-";
-                    }
-                }).AddTo(disposables);
+                )
+                .AddTo(disposables);
 
             model.FormattedCreatedAtDate.Value = FormatDate(DateTime.Now, model.CreatedAtDate.Value);
             model.FormattedInstalledDate.Value = FormatDate(DateTime.Now, model.InstalledDate.Value);
 
             if (model._linkedLoadoutItemsDisposable.Disposable is null)
             {
-                model._linkedLoadoutItemsDisposable.Disposable = model.LinkedLoadoutItemsObservable.OnUI().SubscribeWithErrorLogging(changeSet => model.LinkedLoadoutItems.ApplyChanges(changeSet));
+                model._linkedLoadoutItemsDisposable.Disposable = model.LinkedLoadoutItemsObservable
+                    .OnUI()
+                    .SubscribeWithErrorLogging(changeSet => model.LinkedLoadoutItems.ApplyChanges(changeSet));
             }
         });
     }

src/NexusMods.App.UI/Pages/LoadoutPage/LoadoutViewModel.cs

@@ -164,7 +164,7 @@ public LoadoutViewModel(IWindowManager windowManager, IServiceProvider servicePr
                 configureAwait: false).AddTo(disposables);
 
                 // Compute the target group for the ViewFilesCommand
-                Adapter.SelectedModels.ObserveCountChanged()
+                Adapter.SelectedModels.ObserveCountChanged(notifyCurrentCount: true)
                     .Select(this, static (count, vm) => count == 1 ? vm.Adapter.SelectedModels.First() : null)
                     .ObserveOnThreadPool()
                     .Select(_connection,

src/NexusMods.Collections/NexusMods.Collections.csproj

@@ -4,6 +4,7 @@
 
     <ItemGroup>
       <ProjectReference Include="..\Abstractions\NexusMods.Abstractions.Collections\NexusMods.Abstractions.Collections.csproj" />
+      <ProjectReference Include="..\Abstractions\NexusMods.Abstractions.FileExtractor\NexusMods.Abstractions.FileExtractor.csproj" />
       <ProjectReference Include="..\Abstractions\NexusMods.Abstractions.Jobs\NexusMods.Abstractions.Jobs.csproj" />
       <ProjectReference Include="..\Abstractions\NexusMods.Abstractions.Library\NexusMods.Abstractions.Library.csproj" />
       <ProjectReference Include="..\ArchiveManagement\NexusMods.FileExtractor\NexusMods.FileExtractor.csproj" />