fix(database): handle empty nullable nested relations

packages/database/src/Mappers/SelectModelMapper.php

@@ -83,13 +83,15 @@ private function values(ModelInspector $model, array $data): array
             $relation = $model->getRelation($key);
 
             if ($relation instanceof BelongsTo || $relation instanceof HasOne || $relation instanceof HasOneThrough) {
-                if ($relation->property->isNullable() && array_filter($data[$relation->name] ?? []) === []) {
-                    $data[$relation->name] = null;
-                } elseif (is_array($data[$relation->name] ?? null)) {
+                if (is_array($data[$relation->name] ?? null)) {
                     $relationModel = inspect($relation);
                     $data[$relation->name] = $this->values($relationModel, $data[$relation->name]);
                 }
 
+                if ($relation->property->isNullable() && $this->relationDataIsEmpty($data[$relation->name] ?? null)) {
+                    $data[$relation->name] = null;
+                }
+
                 continue;
             }
 
@@ -108,6 +110,25 @@ private function values(ModelInspector $model, array $data): array
         return $data;
     }
 
+    private function relationDataIsEmpty(mixed $value): bool
+    {
+        if ($value === null) {
+            return true;
+        }
+
+        if (! is_array($value)) {
+            return false;
+        }
+
+        foreach ($value as $item) {
+            if (! $this->relationDataIsEmpty($item)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     public function normalizeRow(ModelInspector $model, array $row, MutableArray $data): array
     {
         $mainTable = $model->getTableName();

tests/Integration/Database/Mappers/SelectModelMapperTest.php

@@ -3,8 +3,11 @@
 namespace Tests\Tempest\Integration\Database\Mappers;
 
 use PHPUnit\Framework\Attributes\Test;
+use Tempest\Database\BelongsTo;
 use Tempest\Database\BelongsToMany;
+use Tempest\Database\Eager;
 use Tempest\Database\Exceptions\RelationWasMissing;
+use Tempest\Database\HasOne;
 use Tempest\Database\IsDatabaseModel;
 use Tempest\Database\Mappers\SelectModelMapper;
 use Tempest\Database\Migrations\CreateMigrationsTable;
@@ -362,6 +365,25 @@ public function array_of_serialized_enums(): void
         $this->assertSame(EnumToBeMappedToArray::USER, $users[0]->roles[1]);
     }
 
+    #[Test]
+    public function nullable_eager_relation_with_nested_empty_relations_maps_to_null(): void
+    {
+        $users = map([
+            [
+                'users.id' => 1,
+                'users.name' => 'Rado',
+                'profile.id' => null,
+                'profile.createdBy.id' => null,
+                'profile.createdBy.name' => null,
+                'profile.updatedBy.id' => null,
+                'profile.updatedBy.name' => null,
+            ],
+        ])->with(mapper: SelectModelMapper::class)->to(to: UserWithNullableEagerProfile::class);
+
+        $this->assertSame(expected: 'Rado', actual: $users[0]->name);
+        $this->assertNull(actual: $users[0]->profile);
+    }
+
     private function data(): array
     {
         return [
@@ -505,6 +527,40 @@ final class ObjectWithArrayEnumProperty
     public array $roles;
 }
 
+#[Table(name: 'users')]
+final class UserWithNullableEagerProfile
+{
+    use IsDatabaseModel;
+
+    public string $name;
+
+    #[Eager]
+    #[HasOne]
+    public ?NullableEagerProfile $profile = null;
+}
+
+#[Table(name: 'profiles')]
+final class NullableEagerProfile
+{
+    use IsDatabaseModel;
+
+    #[Eager]
+    #[BelongsTo]
+    public ?NullableEagerUserLookup $createdBy = null;
+
+    #[Eager]
+    #[BelongsTo]
+    public ?NullableEagerUserLookup $updatedBy = null;
+}
+
+#[Table(name: 'users')]
+final class NullableEagerUserLookup
+{
+    use IsDatabaseModel;
+
+    public string $name;
+}
+
 enum EnumToBeMappedToArray: string
 {
     case ADMIN = 'admin';