在 Symfony 中查询删除外键

Question

谁能帮我解决这个问题，创建一个查询，如果用户试图删除外键，它会给他们一个错误，而不是使用异常。

public function findByStudent($studentid, $id){
    return $this->getEntityManager()
            ->createQuery(
              'select p from AcmeDemoBundle:Student 
                    where studentid = :studentid AND id= :id
                    ')
            ->setParameter('student',$studentid)
            ->setParameter('id',$id)        


                    ;

}

更新

$student= $em->getRepository('AcmeDemoBundle:Student')->findOneby($studentid, $courdeId, $LecturerId);
        if($student){
             $this->addFlash('error','ERROR! You cannot delete this Student');   
        }

        $em->remove($student);
        $em->flush();
        $this->addFlash('error','Student Deleted');
    }
    return $this->redirect($this->generateUrl('student'));

学生实体

<?php

namespace Acme\DemoBundle\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * Student
 *
 * @ORM\Table()
 * @ORM\Entity
 */
class Student
{
/**
 * @var integer
 *
 * @ORM\Column(name="studentid", type="integer")
 * @ORM\Id
 * @ORM\GeneratedValue(strategy="AUTO")
 */

private $studentid;

/**
 * @var string
 *
 * @ORM\Column(name="name", type="string", length=255)
 */
private $name;

/**
 * @var string
 *
 * @ORM\Column(name="address", type="string", length=255)
 */
private $address;

/**
 * @var string
 *
 * @ORM\Column(name="Programme", type="string", length=255)
 */
private $programme;

/**
 * @var \DateTime
 *
 * @ORM\Column(name="Date of Birth", type="date")
 */
private $dateOfBirth;

/**
 * @var string
 *
 * @ORM\Column(name="Contact", type="string", length=255)
 */
private $contact;


/**
 * Get id
 *
 * @return integer 
 */
public function getId()
{
    return $this->id;
}

/**
 * Set studentid
 *
 * @param integer $studentid
 * @return Student
 */
public function setStudentid($studentid)
{
    $this->studentid = $studentid;

    return $this;
}

/**
 * Get studentid
 *
 * @return integer 
 */
public function getStudentid()
{
    return $this->studentid;
}

/**
 * Set name
 *
 * @param string $name
 * @return Student
 */
public function setName($name)
{
    $this->name = $name;

    return $this;
}

/**
 * Get name
 *
 * @return string 
 */
public function getName()
{
    return $this->name;
}

/**
 * Set address
 *
 * @param string $address
 * @return Student
 */
public function setAddress($address)
{
    $this->address = $address;

    return $this;
}

/**
 * Get address
 *
 * @return string 
 */
public function getAddress()
{
    return $this->address;
}

/**
 * Set programme
 *
 * @param string $programme
 * @return Student
 */
public function setProgramme($programme)
{
    $this->programme = $programme;

    return $this;
}

/**
 * Get programme
 *
 * @return string 
 */
public function getProgramme()
{
    return $this->programme;
}

/**
 * Set dateOfBirth
 *
 * @param \DateTime $dateOfBirth
 * @return Student
 */
public function setDateOfBirth($dateOfBirth)
{
    $this->dateOfBirth = $dateOfBirth;

    return $this;
}

/**
 * Get dateOfBirth
 *
 * @return \DateTime 
 */
public function getDateOfBirth()
{
    return $this->dateOfBirth;
}

/**
 * Set contact
 *
 * @param string $contact
 * @return Student
 */
public function setContact($contact)
{
    $this->contact = $contact;

    return $this;
}

/**
 * Get contact
 *
 * @return string 
 */
public function getContact()
{
    return $this->contact;
}

}

<entity name="AcmeDemoBundle\Entity\Course" table="Course" repository-class="AcmeDemoBundle\Entity\CourseRepository">
<indexes>
  <index name="IDX_1B4F90669AD94696" columns="studentid"/>
</indexes>
<id name="id" type="integer" column="id">
  <generator strategy="IDENTITY"/>
</id>
<field name="name" type="string" column="string" nullable="false"/>

<many-to-one field="studentid" target-entity="Student">
  <join-columns>
    <join-column name="studentid" referenced-column-name="studentid"/>
  </join-columns>
</many-to-one>

已更新自定义存储库

        public function findByStudentid($studentid, $id, tutorId)
{
     return $this->getEntityManager()
     ->createQuery('select s from AcmeDemoBundle:Student s
                    where s.studentid = :studentid AND s.id= :id or studentid = :studentid AND p.tutorId= :tutorId ')
              ->setParameter('studentid',$studentid)
            ->setParameter('id',$id)        
            ->setParameter('tutorId',$tutorId)  
            ->getResults();
     $student= $this->entityManager->getRepository('AcmeDemoBundle:Student')->findBy(['studentid' => $studentid]);
     if ($student){
         return false;
     } else {
         return true;
     }
}

Answer 1

使用try catch语法

use Doctrine\DBAL\Exception\ForeignKeyConstraintViolationException;

try {
    $em = $this->getDoctrine()->getManager();
    $student = $em->getRepository("AppBundle:Student")->findOneBy([
        'studentId' => $studentId,
        'id' => $id
    ]);
    if(!$student) { ... your code ... }

    $em->remove($student);
    $em->flush(); // it there is exception connected with FK, then
    // catch it below
} catch(ForeignKeyConstraintViolationException $e) {
    return $this->render(':error:page.html.twig',['error'=>$e]);
}

你也可以赶上

use Doctrine\DBAL\Exception\UniqueConstraintViolationException;

以及许多其他与数据库相关的异常。如果您只比较 $studentId 和 $id 的给定值，则不要在 DQL 中键入查询。方法 findOneBy 是最简单的解决方案。我建议在更复杂的查询中使用 DQL。

如果我的回答好像不清楚，或者你还想得到别的东西，请把你的问题说清楚，在评论里告诉我。

Answer 2

在你的学生资料库中创建类似这样的东西：

public function isDeletable($student)
{
     //your conditions here
     $courses = $this->entityManager->getRepository('Courses')->findBy(['student' => $student]);
     $tutor = $this->entityManager->getRepository('Tutors')->findBy(['student' => $student]);
     if ($courses || $tutor){
         return false;
     } else {
         return true;
     }
}

并在删除前调用此函数。如果显示 true - 删除记录，如果显示 false - 显示错误页面。

在 Symfony 中查询删除外键

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