Doctrine not honoring self-referencing relationship

Question

I have a User entity with a self-referencing one-to-many relationship - Every User owns a set of students (who are also users):

<?php

namespace AppBundle\Entity;
use FOS\UserBundle\Model\User as BaseUser;
use Doctrine\Common\Collections\ArrayCollection;


/**
 * User
 */
class User extends BaseUser
{
    /**
     * @var int
     */
    protected $id;

    private $students;

    // ....

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

    public function __construct() {
        $this->students = new ArrayCollection();
        // ...
        parent::__construct();
    }
    /**
     * Remove student
     *
     * @return User
     */
    public function removeStudent($student)
    {
        $this->students->removeElement($student);
        return $this;
    }

    /**
     * Add a student
     *
     * @param User $students
     *
     * @return User
     */
    public function addStudent($student)
    {
        $this->students->add($student);
        return $this;
    }

    /**
     * Get students
     *
     * @return User
     */
    public function getStudents()
    {
        $this->students;
    }

    /**
     * Set students
     *
     * @param User $students
     *
     * @return User
     */
    public function setStudents($students)
    {
        $this->students = $students;

        return $this;
    }
    // ....
}

The mapping is done as a one-to-many unidirectional with join table

AppBundle\Entity\User:
    type: entity
    table: null
    repositoryClass: AppBundle\Repository\UserRepository
    id:
        id:
            type: integer
            id: true
            generator:
                strategy: AUTO
    fields:

    // ...

    manyToMany:
      students:
        targetEntity: User
        joinTable:
          name: mentors_students
          joinColumns:
            mentor_id:
              referencedColumnName: id
          inverseJoinColumns:
            student_id:
              referencedColumnName: id
              unique: true              
    lifecycleCallbacks: {  }

Now when I add/edit a user using the EasyAdmin bundle, I can add the students for that user. However, when I retrieve the entity, the students property is always null. For example, when I view the list of users:

Here the user 'sagarl3232' is supposed to be a student of 'sj' but the view above clearly shows the property when retrieved is null.

The entity is persisted correctly in the database. That is, the join table has the right values:

Why is Doctrine doing this to me? Isn't it supposed to hydrate the students array automatically?

Answer 1

Your getter doesnt return anything!

/**
 * Get students
 *
 * @return User[]
 */
public function getStudents()
{
    return $this->students;
}

BTW why you should adjust the docblock too. The getter is supposed to return an array User[]