带有连接的symfony 3子查询

$this->createQueryBuilder('project')
        ->select('
            project.id, 
            project.name, 
            project.price,
            project.cost,
            project_company.name as company')
        ->addSelect("SUM(project_transactions.sum) AS spent")
        ->leftJoin('project.company', 'project_company')
        ->leftJoin('project.transactions', 'project_transactions')
        ->groupBy('project.id')
        ->getQuery()
        ->execute();

这是工作要求。我需要将以下内容添加到此查询的选择中：payment_types 表中的值列，它与 payment_type_id 字段的交易相关。结果我需要在子查询上再做一个连接，这已经是一个加入自己。如何实施？

manyToOne:
      paymentType:
          targetEntity: PaymentType
          inversedBy: transactions
          joinColumn:
              name: payment_type_id
              referencedColumnName: id

这是交易表与 payment_types 表的连接