CakePhp 3.x select 包含行为 NULL 的地方

CakePhp 3.x select contain where row is NULL

我不清楚如何在 Cakephp

中使用 contain() 获取在另一行中没有引用的记录
public function initialize(array $config)
{        
    $this->hasmany('Prior', [
        'className' => 'Prior',
        'foreignKey' => 'photoID'
    ]);
}

public function search()
{
    $query = $this->find('all')->contain(['Prior']);
    return $query;
}

这 return 类似于:

-> results
  ->0
     ->ID = 1
     ->Prior = null

  ->1
     ->ID = 2
     ->Prior = array()

  ->2
     ->ID = 3
     ->Prior = array()

  ->3
     ->ID = 4
     ->Prior = null

如何才能 return 只有 NULL 结果?

使用notMatching(参见cookbook

$this->find('all')
    ->contain(['Prior'])
    ->notMatching('Prior');