`NestedSet::isNode($node)` returns false negative

[nagmat84]

I have implemented a Eloquent class which uses the trait NodeTrait. Deleting objects of such a class fails with an InvalidArgumentException exception "Model must be node." in BaseRelation::__construct() due to NestedSet::isNode returning false.

The call stack in reverse order is

BaseRelation.php:40, Kalnoy\Nestedset\DescendantsRelation->__construct()
NodeTrait.php:252, App\Models\Album->descendants()
NodeTrait.php:631, App\Models\Album->deleteDescendants()
NodeTrait.php:56, App\Models\Album::Kalnoy\Nestedset\{closure:/var/www/localhost/lychee/vendor/kalnoy/nestedset/src/NodeTrait.php:55-57}()
Dispatcher.php:392, Illuminate\Events\Dispatcher->Illuminate\Events\{closure:/var/www/localhost/lychee/vendor/laravel/framework/src/Illuminate/Events/Dispatcher.php:387-393}()
Dispatcher.php:237, Illuminate\Events\Dispatcher->dispatch()
HasEvents.php:189, App\Models\Album->fireModelEvent()
Model.php:1158, App\Models\Album->delete()

(Note: App\Models\Album in the last line is my own model).

The Album is defined as follows

class Album extends BaseAlbum {
  use NodeTrait;
  ...
}

and BaseAlbum is

abstract class BaseAlbum extends Model implements AbstractAlbum {
  ...
}

NestedSet::isNode coverts the object to an array in order to check whether the object uses the trait NodeTrait. The array conversion returns

array (
  'attributes' => array (
    'id' => '16356901022810',
    'parent_id' => NULL,
    'license' => 'reserved',
    'cover_id' => NULL,
    '_lft' => '21',
    '_rgt' => '24',
    'min_taken_at' => NULL,
    'max_taken_at' => NULL,
  ),
  'casts' => array (
    'min_taken_at' => 'datetime',
    'max_taken_at' => 'datetime',
    'cover_id' => 'integer',
    'parent_id' => 'integer',
    '_lft' => 'integer',
    '_rgt' => 'integer',
  ),
  'hidden' => array (
    0 => 'base_class',
    1 => 'cover',
    2 => '_lft',
    3 => '_rgt',
    4 => 'parent',
    5 => 'all_photos',
    6 => 'base_class',
  ),
  'with' => array (
    0 => 'cover',
    1 => 'thumb',
    2 => 'base_class',
  ),
  'incrementing' => false,
  'connection' => 'sqlite',
  'table' => 'albums',
  'primaryKey' => 'id',
  'keyType' => 'int',
  'withCount' => array (),
  'perPage' => 15,
  'exists' => true,
  'wasRecentlyCreated' => false,
  'original' => 
  array (
    'id' => '16356901022810',
    'parent_id' => NULL,
    'license' => 'reserved',
    'cover_id' => NULL,
    '_lft' => '21',
    '_rgt' => '24',
    'min_taken_at' => NULL,
    'max_taken_at' => NULL,
  ),
  'changes' => array (),
  'classCastCache' => array (),
  'dates' => array (),
  'dateFormat' => NULL,
  'appends' => array (),
  'dispatchesEvents' => array (),
  'observables' => array (),
  'relations' => array (
    'cover' => NULL,
    'thumb' => NULL,
    'base_class' => App\Models\BaseAlbumImpl::__set_state(array(
      'table' => 'base_albums',
      'incrementing' => false,
      'attributes' => array (
        'id' => '16356901022810',
        'created_at' => '2021-10-31 14:21:42',
        'updated_at' => '2021-10-31 14:21:44',
        'title' => 'NEW_TEST',
        'description' => 'new description',
        'owner_id' => '0',
        'is_public' => '0',
        'grants_full_photo' => '1',
        'requires_link' => '0',
        'is_downloadable' => '0',
        'is_share_button_visible' => '0',
        'is_nsfw' => '0',
        'password' => NULL,
        'sorting_col' => NULL,
        'sorting_order' => 'ASC',
      ),
      'casts' => array (
        'created_at' => 'datetime',
        'updated_at' => 'datetime',
        'is_public' => 'boolean',
        'requires_link' => 'boolean',
        'is_nsfw' => 'boolean',
        'owner_id' => 'integer',
        'id' => 'integer',
      ),
      'hidden' => array (
        0 => 'owner',
        1 => 'password',
      ),
      'appends' => array ( 0 => 'has_password' ),
      'with' => array ( 0 => 'owner' ),
      'connection' => 'sqlite',
      'primaryKey' => 'id',
      'keyType' => 'int',
      'withCount' => array (),
      'perPage' => 15,
      'exists' => true,
      'wasRecentlyCreated' => false,
      'original' => array (
        'id' => '16356901022810',
        'created_at' => '2021-10-31 14:21:42',
        'updated_at' => '2021-10-31 14:21:44',
        'title' => 'NEW_TEST',
        'description' => 'new description',
        'owner_id' => '0',
        'is_public' => '0',
        'grants_full_photo' => '1',
        'requires_link' => '0',
        'is_downloadable' => '0',
        'is_share_button_visible' => '0',
        'is_nsfw' => '0',
        'password' => NULL,
        'sorting_col' => NULL,
        'sorting_order' => 'ASC',
      ),
      'changes' => array (),
      'classCastCache' => array (),
      'dates' => array (),
      'dateFormat' => NULL,
      'dispatchesEvents' => array (),
      'observables' => array (),
      'relations' => array (
        'owner' => App\Models\User::__set_state(array(
          'fillable' => array (
            0 => 'username',
            1 => 'password',
            2 => 'email',
          ),
          'hidden' => array (
            0 => 'password',
            1 => 'remember_token',
            2 => 'created_at',
            3 => 'updated_at',
          ),
          'casts' => array (
            'upload' => 'int',
            'lock' => 'int',
          ),
          'connection' => 'sqlite',
          'table' => 'users',
          'primaryKey' => 'id',
          'keyType' => 'int',
          'incrementing' => true,
          'with' => array (),
          'withCount' => array (),
          'perPage' => 15,
          'exists' => true,
          'wasRecentlyCreated' => false,
          'attributes' => array (
            'id' => '0',
            'username' => '',
            'password' => '',
            'upload' => '0',
            'lock' => '0',
            'remember_token' => NULL,
            'created_at' => '2021-10-31 13:05:22',
            'updated_at' => '2021-10-31 13:05:22',
            'email' => NULL,
          ),
          'original' => array (
            'id' => '0',
            'username' => '',
            'password' => '',
            'upload' => '0',
            'lock' => '0',
            'remember_token' => NULL,
            'created_at' => '2021-10-31 13:05:22',
            'updated_at' => '2021-10-31 13:05:22',
            'email' => NULL,
          ),
          'changes' => array (),
          'classCastCache' => array (),
          'dates' => array (),
          'dateFormat' => NULL,
          'appends' => array (),
          'dispatchesEvents' => array (),
          'observables' => array (),
          'relations' => array (),
          'touches' => array (),
          'timestamps' => true,
          'visible' => array (),
          'guarded' => array ( 0 => '*' ),
          'rememberTokenName' => 'remember_token',
        )),
      ),
      'touches' => array (),
      'timestamps' => true,
      'visible' => array (),
      'fillable' => array (),
      'guarded' => array ( 0 => '*' ),
    )),
  ),
  'touches' => array (),
  'timestamps' => false,
  'visible' => array (),
  'fillable' => array (),
  'guarded' => array ( 0 => '*' ),
  'pending' => NULL,
  'moved' => false,
)

(As you can see, the array does indeed not report the trait NodeTrait).

As I know for sure that Album is a node everything just works fine if I patch NestedSet::isNode to skip the buggy check. I haven't yet figured out under what conditions the construction (array)some_object returns or does not return the used traits. However, using a conversion to an array is not a reliable method.

Half a solution

There is the SPL method class_uses which perfectly works fine for me in all cases, but it is not a general solution, because it does not return traits of parent classes. This means, for another model hierarchy which may use NodeTrait on a common base class for several models, class_uses will also fail.

Proposed solution

Create an interface Node which declares all the necessary methods and let NodeTrait provide the implementation of these methods. Then check with some_object instanceof Node if the model is a node. This is the only reliable method.

Drawback: All users of the library are enforced to make their models implement the said interface. But this is the purpose of interfaces (aka "contracts").