Doctrine 2 OneToMany Cascade SET NULL

问题

The error

Cannot delete or update a parent row: a foreign key constraint fails.

The classes

class Teacher {

    /**
     *@ORM\OneToMany(targetEntity="publication", mappedBy="teacher")
     */
    protected $publications;
}

class Publication {

    /**
     * @ORM\ManyToOne(targetEntity="Teacher", inversedBy="publications")
     * @ORM\JoinColumn(name="teacher_id", referencedColumnName="id")
     */
    protected $teacher;
}

I want

What I want is to make it that when you delete a teacher, the id_teacher is modified to NULL. I want to keep the publication but without reference to Professor.

I don't know how do that in Doctrine, Is it possible? Or always the relationship has to be with a teacher?

回答1:

You should add the option onDelete="SET NULL" in the annotation of your entity Publication like this:

class Publication
{
    /**
    * @ORM\ManyToOne(targetEntity="Teacher", inversedBy="publications")
    * @ORM\JoinColumn(name="teacher_id", referencedColumnName="id", onDelete="SET NULL")
    */
    protected $teacher;
}

Cheers!

来源：https://stackoverflow.com/questions/8858645/doctrine-2-onetomany-cascade-set-null