Question

我遇到ManyToMany关联问题。我无法弄清楚如何从数据库中获取数据。我有2个实体 - 教师和主题。

课程科目

/**
 *
 * @ORM\ManyToMany(targetEntity="Teacher", mappedBy="subjects")
 */
private $teachers;


public function __construct() {

    $this->teachers = new ArrayCollection();
}

/**
 * Add teacher
 *
 * @param \AppBundle\Entity\Teacher $teacher
 *
 * @return Subject
 */
public function addTeacher(\AppBundle\Entity\Teacher $teacher)
{
    $this->teachers[] = $teacher;

    return $this;
}

/**
 * Remove teacher
 *
 * @param \AppBundle\Entity\Teacher $teacher
 */
public function removeTeacher(\AppBundle\Entity\Teacher $teacher)
{
    $this->teachers->removeElement($teacher);
}

/**
 * Get teachers
 *
 * @return \Doctrine\Common\Collections\Collection
 */
public function getTeachers()
{
    return $this->teachers;
}

实体老师

班主任

/**
 *
 * @ORM\ManyToMany(targetEntity="Subject", inversedBy="teachers")
 */
private $subjects;

public function __construct()
    {
        $this->subjects = new ArrayCollection();
    }

/**
 * Add subject
 *
 * @param \AppBundle\Entity\Subject $subject
 *
 * @return Teacher
 */
public function addSubject(\AppBundle\Entity\Subject $subject)
{
    $this->subjects[] = $subject;

    return $this;
}

/**
 * Remove subject
 *
 * @param \AppBundle\Entity\Subject $subject
 */
public function removeSubject(\AppBundle\Entity\Subject $subject)
{
    $this->subjects->removeElement($subject);
}

/**
 * Get subjects
 *
 * @return \Doctrine\Common\Collections\Collection
 */
public function getSubjects()
{
    return $this->subjects;
}

我想要做的就是从教师+与他们相关的主题中获取所有信息。

我的控制器看起来应该怎么做？

我尝试通过

来做到这一点

   $teacher = $this->getDoctrine()->getRepository(Teacher::class)->findAll();

    return $this->render('admin/adminDashboard.html.twig', [
                'teachers' => $teacher]);

但我仍然有错误

Answer 1

首先，我的建议是将$ teacher变量改为$ teacher findAll（）方法返回一个数组，因此你必须遍历它。在您的控制器中：

Signature rsa = Signature.getInstance("SHA1withRSA");  
rsa.initSign(getPrivate(“<RSAKeyValue><Modulus>oQRshGhLf2Fh...”));
rsa.update(message.getBytes());
byte[] signed = rsa.sign();

在你的树枝模板中：

foreach($teachers as $teacher) { // Here you have $teacher and you can do $teacher->getSubjects() }

如果这不起作用，请告诉我们你会得到什么样的错误。这都假设您在数据库中有条目，或者从您获取实体的任何地方开始。

Answer 2

如果{% for t in teachers %}{{dump(t.subjects.count)}}{% endfor %}有效，则表示数据存在。

如果你的意思是{{teacher.subjects}}抛出错误：在渲染模板期间抛出异常（“Catchable Fatal Error：类Doctrine \ ORM \ PersistentCollection的对象无法转换为字符串

类Doctrine \ ORM \ PersistentCollection 的对象引用subjects，它作为一个集合，不能像字符串一样被抛入html标记。

取决于您希望如何呈现数据，但基本要素是：

{% for t in teachers %} <tr> {% for s in t.subjects %} <td>s.getName</td> {% endfor %} </tr> {% endfor %}

假设subject实体有一个属性name和一个getter。希望你得到要点。

让我知道

Symfony3从具有ManyToMany关联的实体获取数据

2 个答案: