Question

让我说我有部门，大学实体如跟

class Department{
     private $name;

     private $studentCount;


    /**  
    *@ORM\ManyToOne(targetEntity="\CAPP\CollegeBundle\Entity\College", inversedBy="departments")
    *@ORM\JoinColumn(name="college_id", referencedColumnName="id", nullable=false)
    **/
     private $college
}

class College
{

   private $name;

   private $departmentCount;

   /**
   *@ORM\OneToMany(targetEntity="\CAPP\DepartmentBundle\Entity\Department", mappedBy="college", cascade={"all"}, orphanRemoval=true)
   */
   private $departments
}

当我编写一个doctrine查询构建器来获取具有以下查询的所有部门时

METHOD1:
return $this->getQb()->select("dp")
            ->from("DepartmentBundle:Department", "dp")
            ->getQuery()
            ->getResult()
            ;

我的结果包含所有字段，但当我尝试访问特定字段name和college时，请使用以下查询

METHOD2:
return $this->getQb()->select("dp.name, dp.college")
            ->from("DepartmentBundle:Department", "dp")
            ->getQuery()
            ->getResult()
            ;

我收到错误

col 10 near＆＃39; college FROM＆＃39;：错误：无效的PathExpression。必须是StateFieldPathExpression。

我在这里犯了什么错误，学说在query method 1上获取了各个大学实体的所有部门，但当我尝试query method 2时，为什么会抛出错误。

Answer 1

如果不是纯粹用于优化，则使用partial object的学说不鼓励。你应该按照预期使用学说：完全面向对象。

$this->getQb('dp')
    ->select("dp")
    ->from("DepartmentBundle:Department", "dp")

如果你真的想使用partial：

$this->getQb('dp')
    ->select("partial dp.{name,college}")
    ->from("DepartmentBundle:Department", "dp")

Answer 2

请试试这个：

return $this->getQb('dp')->select('IDENTITY(dp.name)', 'IDENTITY(dp.college)')
            ->from("DepartmentBundle:Department", "dp")
            ->getQuery()
            ->getResult()
            ;

如果dp.name或dp.college是复合键，那么您需要添加IDENTITY以使查询起作用并解决问题

Answer 3

不确定这是否是最佳答案，但我只是抓住该集合，然后使用get / set方法来提取信息...

$department = $this->getQb()->select("dp")
            ->from("DepartmentBundle:Department", "dp")
            ->getQuery()
            ->getResult();

$name = $department->getName(); 
$college = $department->getCollege();

了解Doctrine Query Builder？

3 个答案: