Extending an entity class in doctrine - php

Question

I'm trying to extend a class used as a doctrine entity, but for some reason I keep getting the error:
There is no column with name 'location_id' on table 'admin_subdivisions'
When I say extend, I mean at the php level NOT the database level. I simply want to create another table, with an extra column. I have several entities which extend the following abstract class
abstract class LocationProxy
{
/**
* #ORM\Id
* #ORM\OneToOne(targetEntity="Location", cascade={"ALL"}, fetch="LAZY")
* #ORM\JoinColumn(name="location_id", referencedColumnName="location_id", nullable=false)
*
* #var Location
*/
protected $location;
}
None of these second level classes give me any problems. Now, I want to extend this second level class
/**
* #ORM\Entity()
* #ORM\Table(name="admin_divisions")
*/
class AdminDivision extends LocationProxy
{
}
with this
/**
* #ORM\Entity()
* #ORM\Table(name="admin_subdivisions")
*/
class AdminSubDivision extends AdminDivision
{
}
but, it produces the error. Can anybody point out what I am doing wrong?
here is the Location class definition
/**
* #ORM\Entity()
* #ORM\Table(name="locations")
*/
class Location
{
/**
* #ORM\Id
* #ORM\Column(name="location_id", type="integer", options={"unsigned"=true})
*
* #var int
*/
private $id;
}

Answer 1

You must specify the inheritence type so that doctrine knows how to build the tables for the subclasses: http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/inheritance-mapping.html#mapped-superclasses
In you case you will need to add the following Annotations to your abstract LocationProxy Class:
#ORM\Entity
#ORM\InheritanceType("JOINED")
#ORM\DiscriminatorColumn(name="discr", type="string")
Or choose a different inheritance type
So the whole class will look like this:
/**
* #ORM\Entity
* #ORM\InheritanceType("JOINED")
* #ORM\DiscriminatorColumn(name="discr", type="string")
*/
abstract class LocationProxy {
/**
* #ORM\Id
* #ORM\OneToOne(targetEntity="De\Gregblog\Receipts\Location", cascade={"ALL"}, fetch="LAZY")
* #ORM\JoinColumn(name="location_id", referencedColumnName="location_id", nullable=false)
*
* #var Location
*/
protected $location;
}