Doctrine2 cascade remove with multiple parents - symfony

Question

I have a series of classes with a slightly complicated set of references between the properties of those classes. I am trying to remove an entity and have that remove be cascaded to its children, but I'm running into foreign key constraint errors. Here is an example of my class structure:
<?php
/**
* #ORM\Entity
* #ORM\Table(name="student_tests")
*/
class StudentTest implements IEntityAccess {
/**
*
* #var int
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
/**
* #var StudentTestItem[]
* #ORM\OneToMany(targetEntity="StudentTestItem", mappedBy="studentTest", cascade{"remove","persist"})
*/
protected $studentTestItems;
/**
* #var Test
* #ORM\ManyToOne(targetEntity="Test", inversedBy="studentTests")
*/
protected $test;
/**
* #var \DateTime
* #ORM\Column(type="datetime", nullable=true)
*/
protected $created;
/**
* #var User
* #ORM\ManyToOne(targetEntity="User", inversedBy="studentTests")
*/
protected $student;
}
//...
<?php
/**
* #ORM\Entity
* #ORM\Table(name="student_test_items")
*/
class StudentTestItem {
/**
*
* #var int
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
/**
* #var StudentTest
* #ORM\ManyToOne(targetEntity="StudentTest", inversedBy="studentTestItems")
*/
protected $studentTest;
/**
* #var User
* #ORM\ManyToOne(targetEntity="User", inversedBy="studentTestItems", cascade={"persist"})
*/
protected $student;
/**
* #var TestItem
* #ORM\ManyToOne(targetEntity="TestItem", inversedBy="studentTestItems", cascade{"persist"})
*/
protected $testItem;
}
//...
/**
*
* #ORM\Table(name="tests")
* #ORM\Entity
*
* #ORM\HasLifecycleCallbacks
*/
class Test implements IEntityAccess {
/**
*
* #var int
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
/**
* #var \DateTime
* #ORM\Column(type="datetime", nullable=true)
*/
protected $startDate;
/**
* #var StudentTest[]
* #ORM\OneToMany(targetEntity="StudentTest", mappedBy="test" )
*/
protected $studentTests;
/**
* #var TestItem[]
* #ORM\OneToMany(targetEntity="TestItem", mappedBy="test", cascade={"all"})
*/
protected $items;
}
//...
/**
*
* #ORM\Table(name="test_items")
* #ORM\Entity
*/
abstract class TestItem {
/**
*
* #var int
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
/**
* #var Test
* #ORM\ManyToOne(targetEntity="Test", inversedBy="items")
*/
/**
* #var StudentTestItem[]
* #ORM\OneToMany(targetEntity="StudentTestItem", mappedBy="testItem")
*/
protected $studentTestItems;
}
/**
* This is the primary user object. Used for login and all the other
* good stuff.
*
* #ORM\Table(name="users")
* #ORM\HasLifecycleCallbacks
class User implements AdvancedUserInterface, \Serializable, IEntityAccess
{
/**
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
* #var int
*/
private $id;
/**
* #var StudentTest[]
* #ORM\OneToMany(targetEntity="StudentTest", mappedBy="student", cascade={"persist", "remove"})
*/
protected $studentTests;
/**
* #var StudentTestItem[]
* #ORM\OneToMany(targetEntity="StudentTestItem", mappedBy="student", cascade={"persist", "remove"})
*/
protected $studentTestItems;
}
Let's say I want to delete a student test, and have that delete cascaded to its StudentTestItem children. To do so, I run the following code inside of a controller.
//... blah blah class definition
/**
* Delete a student test
*
* #return \Symfony\Component\HttpFoundation\Response
* #Route("/studenttest/delete", name="student_test_delete")
*/
public function DeleteStudentTestAction(Request $request)
{
$em = $this->getDoctrine()->getManager();
$studentTest = $em->getRepository("MyAcmeBundle:StudentTest")->findOneBy(array("id" => 3));
$em->remove($studentTest);
$em->flush();
return $this->redirect($this->generateUrl('student_delete_success'));
}
When I try to run that code, I get the following error message:
An exception occurred while executing 'DELETE FROM student_tests WHERE id = ?' with params [3]:
SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or update a parent row: a foreign key constraint fails (`my_acme_bundle/student_test_items`, CONSTRAINT `FK_71FA2A7F36BB1A1` FOREIGN KEY (`student_test_id`) REFERENCES `student_tests` (`id`))
500 Internal Server Error - DBALException
NOW, if I remove all references to studentTestItems from the classes, i.e. I comment out $studentTestItems from the TestItem and User classes, it deletes fine without that issue. Why is this happening? Does Doctrine keep track of the parent references through associations or something?

Answer 1

Looks like you forgot to add ON DELETE CASCADE to the foreign key constraint. Try changing the following association in class StudentTestItem:
/**
* #var StudentTest
* #ORM\ManyToOne(targetEntity="StudentTest", inversedBy="studentTestItems")
*/
protected $studentTest;
To this:
/**
* #var StudentTest
* #ORM\ManyToOne(targetEntity="StudentTest", inversedBy="studentTestItems")
* #ORM\JoinColumn(name="student_test_id", referencedColumnName="id", onDelete="CASCADE")
*/
protected $studentTest;