Fix naming filter when collapsing into boxsets

2 files changed, 58 insertions, 15 deletions

diff --git a/Jellyfin.Server.Implementations/Item/BaseItemRepository.cs b/Jellyfin.Server.Implementations/Item/BaseItemRepository.cs
index 46564b24cb..97263e97ee 100644
--- a/Jellyfin.Server.Implementations/Item/BaseItemRepository.cs
+++ b/Jellyfin.Server.Implementations/Item/BaseItemRepository.cs
@@ -998,6 +998,10 @@ public sealed class BaseItemRepository
         if (filter.CollapseBoxSetItems == true)
         {
             dbQuery = ApplyBoxSetCollapsing(context, dbQuery, filter.CollapseBoxSetItemTypes);
+
+            // Apply name-range filters after collapse so BoxSets are filtered by their own name,
+            // not by their children's names.
+            dbQuery = ApplyNameFilters(dbQuery, filter);
         }
 
         dbQuery = ApplyOrder(dbQuery, filter, context);
@@ -1078,6 +1082,29 @@ public sealed class BaseItemRepository
         return context.BaseItems.Where(e => collapsedIds.Contains(e.Id));
     }
 
+    private static IQueryable<BaseItemEntity> ApplyNameFilters(IQueryable<BaseItemEntity> dbQuery, InternalItemsQuery filter)
+    {
+        if (!string.IsNullOrWhiteSpace(filter.NameStartsWith))
+        {
+            var nameStartsWithLower = filter.NameStartsWith.ToLowerInvariant();
+            dbQuery = dbQuery.Where(e => e.SortName!.ToLower().StartsWith(nameStartsWithLower));
+        }
+
+        if (!string.IsNullOrWhiteSpace(filter.NameStartsWithOrGreater))
+        {
+            var startsOrGreaterLower = filter.NameStartsWithOrGreater.ToLowerInvariant();
+            dbQuery = dbQuery.Where(e => e.SortName!.ToLower().CompareTo(startsOrGreaterLower) >= 0);
+        }
+
+        if (!string.IsNullOrWhiteSpace(filter.NameLessThan))
+        {
+            var lessThanLower = filter.NameLessThan.ToLowerInvariant();
+            dbQuery = dbQuery.Where(e => e.SortName!.ToLower().CompareTo(lessThanLower) < 0);
+        }
+
+        return dbQuery;
+    }
+
     private static IQueryable<BaseItemEntity> ApplyNavigations(IQueryable<BaseItemEntity> dbQuery, InternalItemsQuery filter)
     {
         if (filter.TrailerTypes.Length > 0 || filter.IncludeItemTypes.Contains(BaseItemKind.Trailer))
@@ -3073,22 +3100,13 @@ public sealed class BaseItemRepository
             }
         }
 
-        if (!string.IsNullOrWhiteSpace(filter.NameStartsWith))
-        {
-            var nameStartsWithLower = filter.NameStartsWith.ToLowerInvariant();
-            baseQuery = baseQuery.Where(e => e.SortName!.ToLower().StartsWith(nameStartsWithLower));
-        }
-
-        if (!string.IsNullOrWhiteSpace(filter.NameStartsWithOrGreater))
-        {
-            var startsOrGreaterLower = filter.NameStartsWithOrGreater.ToLowerInvariant();
-            baseQuery = baseQuery.Where(e => e.SortName!.ToLower().CompareTo(startsOrGreaterLower) >= 0);
-        }
-
-        if (!string.IsNullOrWhiteSpace(filter.NameLessThan))
+        // When box set collapsing is active, defer name-range filters to after the collapse.
+        // Otherwise, items are filtered by their own name but then collapsed into a BoxSet
+        // whose name may fall in a different range (e.g. "21 Jump Street" is under "#"
+        // but its BoxSet "Jump Street Collection" should appear under "J").
+        if (filter.CollapseBoxSetItems != true)
         {
-            var lessThanLower = filter.NameLessThan.ToLowerInvariant();
-            baseQuery = baseQuery.Where(e => e.SortName!.ToLower().CompareTo(lessThanLower) < 0);
+            baseQuery = ApplyNameFilters(baseQuery, filter);
         }
 
         if (filter.ImageTypes.Length > 0)
diff --git a/MediaBrowser.Controller/Entities/Folder.cs b/MediaBrowser.Controller/Entities/Folder.cs
index 4916ead69a..1b574a2814 100644
--- a/MediaBrowser.Controller/Entities/Folder.cs
+++ b/MediaBrowser.Controller/Entities/Folder.cs
@@ -900,6 +900,11 @@ namespace MediaBrowser.Controller.Entities
             if (user is not null)
             {
                 items = CollapseBoxSetItemsIfNeeded(items, query, this, user, ConfigurationManager, CollectionManager);
+
+                // After collapse, BoxSets may have replaced items whose names matched the filter
+                // but the BoxSet's own name may not match. Re-apply name filtering so BoxSets
+                // appear under the correct letter (e.g. "Jump Street" under J, not under #).
+                items = ApplyNameFilter(items, query);
             }
 
             var filteredItems = items as IReadOnlyList<BaseItem> ?? items.ToList();
@@ -913,6 +918,26 @@ namespace MediaBrowser.Controller.Entities
             return result;
         }
 
+        private static IEnumerable<BaseItem> ApplyNameFilter(IEnumerable<BaseItem> items, InternalItemsQuery query)
+        {
+            if (!string.IsNullOrWhiteSpace(query.NameStartsWith))
+            {
+                items = items.Where(i => i.SortName.StartsWith(query.NameStartsWith, StringComparison.OrdinalIgnoreCase));
+            }
+
+            if (!string.IsNullOrWhiteSpace(query.NameStartsWithOrGreater))
+            {
+                items = items.Where(i => string.Compare(i.SortName, query.NameStartsWithOrGreater, StringComparison.OrdinalIgnoreCase) >= 0);
+            }
+
+            if (!string.IsNullOrWhiteSpace(query.NameLessThan))
+            {
+                items = items.Where(i => string.Compare(i.SortName, query.NameLessThan, StringComparison.OrdinalIgnoreCase) < 0);
+            }
+
+            return items;
+        }
+
         private static IEnumerable<BaseItem> CollapseBoxSetItemsIfNeeded(
             IEnumerable<BaseItem> items,
             InternalItemsQuery query,