doctrine 2 single table inheritance in a many to one relationship - doctrine-orm

Question

I'm working with a Legacy database (osCommerce-based and heavily hacked), which contains a table called orders_total, defined as follows:
CREATE TABLE `orders_total` (
`orders_total_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`orders_id` int(11) unsigned NOT NULL DEFAULT '0',
`title` varchar(255) NOT NULL,
`text` varchar(255) NOT NULL,
`value` decimal(15,4) NOT NULL DEFAULT '0.0000',
`class` varchar(40) NOT NULL,
`sort_order` int(11) NOT NULL DEFAULT '0',
PRIMARY KEY (`orders_total_id`),
KEY `idx_order_id` (`orders_id`)
);
The "class" column defines the type of "total" that the row represents. It's a bit of a mess in that some "totals" are not totals at all, but surcharges, and some are discounts. An example:
+-----------------+-----------+--------------+----------+-----------+----------------------+------------+
| orders_total_id | orders_id | title | text | value | class | sort_order |
+-----------------+-----------+--------------+----------+-----------+----------------------+------------+
| 781797 | 190000 | Sub-Total: | $1427.29 | 1427.2916 | ot_subtotal | 1 |
| 781798 | 190000 | Courier: | $172.05 | 172.0500 | ot_shipping | 2 |
| 781799 | 190000 | Insurance: | $47.62 | 47.6200 | ot_insurance | 3 |
| 781800 | 190000 | Visa/MC Fee: | $41.80 | 41.8000 | ot_surcharge_visa_mc | 4 |
| 781801 | 190000 | <b>Total:</b>| $1688.76 | 1688.7616 | ot_total | 10 |
+-----------------+-----------+--------------+----------+-----------+----------------------+------------+
What I'd like to do is use single table inheritance to split out the table classes into OrderTotal, OrderCharge and OrderDiscount entities, and then through one to many relationships with the Order entity be able to pull up each collection. I've tried the following:
<?php
namespace Shop\Entity;
use Application\Entity\BaseEntity;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\InheritanceType("SINGLE_TABLE")
* #ORM\DiscriminatorColumn(name="class", type="string")
* #ORM\DiscriminatorMap({
* "ot_cc_surcharge" = "OrderCharge",
* "ot_coupon" = "OrderDiscount",
* "ot_insurance" = "OrderCharge",
* "ot_payment_surcharge" = "OrderCharge",
* "ot_paypal_surcharge" = "OrderCharge",
* "ot_shipping" = "OrderCharge",
* "ot_subtotal" = "OrderTotal",
* "ot_surcharge" = "OrderCharge",
* "ot_surcharge_amex" = "OrderCharge",
* "ot_surcharge_paypal" = "OrderCharge",
* "ot_surcharge_visa_mc" = "OrderCharge",
* "ot_total" = "OrderTotal"
* })
* #ORM\Table(name="orders_total")
*
*/
class OrderTotalBase extends BaseEntity {
/*....*/
}
/**
* #ORM\Entity
* #ORM\Table(name="orders_total")
*/
class OrderCharge extends OrderTotalBase {
}
/**
* #ORM\Entity
* #ORM\Table(name="orders_total")
*/
class OrderTotal extends OrderTotalBase {
}
/**
* #ORM\Entity
* #ORM\Table(name="orders_total")
*/
class OrderDiscount extends OrderTotalBase {
}
/*....*/
class Order {
/*....*/
/**
* #ORM\OneToMany(targetEntity="OrderTotal", mappedBy="order", fetch="EAGER")
* #var PersistentCollection
*/
protected $orderTotals;
/**
* #ORM\OneToMany(targetEntity="OrderCharge", mappedBy="order", fetch="EAGER")
* #var PersistentCollection
*/
protected $orderCharges;
/**
* #ORM\OneToMany(targetEntity="OrderDiscount", mappedBy="order", fetch="EAGER")
* #var PersistentCollection
*/
protected $orderDiscounts;
}
Then added the respective getters and setters to the Order class.
Problem is, when I call $order->getOrderCharges(), it returns the entire list of records above all as OrderCharge objects. When I call $order->getOrderTotals() I get exactly the same results but with OrderTotal objects.
Does STI allow me to only get the correct objects according to the #DiscriminatorMap?

Answer 1

While (as explained above) your mappings are invalid, there is a way of fetching all entities in an inheritance according to the discriminator column in DQL:
SELECT r FROM RootEntity r WHERE r INSTANCE OF SubType
Or simply select the correct type with DQL:
SELECT e FROM SubType e
For your OrderTotal case, the association should be
/**
* #ORM\OneToMany(targetEntity="OrderTotal", mappedBy="totalOrder")
* #var \Doctrine\Common\Collections\Collection
*/
protected $orderTotals;
Once you have fixed your mappings and the CLI validator confirms it (orm:validate-schema), that collection will be correctly filtered