Polymorphic associations in doctrine 2? - doctrine

Question

I need a concrete sample of code with doctrine 2 that uses "polymorphic associations".
Let me clarify myself. I have a Entity called Contract and a contract can have many price rules and these price rules can be different kind of classes and presisted in different tables. I suppose this is what's polymorphic associations for or am I wrong?
class contract {
private $id;
private $priceRules;
}
class discountRule implements priceRule{
function calculate() {
// calculate new price after this rule
}
}
class extraSpecialRule implements priceRule {
function calculate() {
// calculate new price after this rule
}
}
There can be new types of price rules in the future,so how can I associate these rules to the main entity and presist them in seperate tables?
Update:
This is my new code:
contract.php
namespace Entities;
use Doctrine\Common\Collections\ArrayCollection;
/**
* #Entity #Table(name="contract")
*/
class Contract {
/**
*
* #Id #Column(type="integer")
* #GeneratedValue(strategy="AUTO")
*/
private $id;
/**
*
* #Column(type="integer")
*/
private $propertyId;
/**
*
* #Column(type="integer")
*/
private $agencyId;
/**
*
* #OneToMany(targetEntity="priceRule" ,mappedBy="contract")
*
*/
private $priceRules;
public function __construct($propertyId,$agencyId){
$this->propertyId=$propertyId;
$this->agencyId=$agencyId;
$this->priceRules=new ArrayCollection();
}
public function addPriceRule(priceRule $rule){
$this->priceRules[]=$rule;
}
public function getPriceRules(){
return $this->priceRules;
}
}
pricerule.php
namespace Entities;
/**
* #Entity
* #InheritanceType("JOINED")
* #DiscriminatorColumn(name="discr" , type="string")
* #DiscriminatorMap({"discountrule"="discountRule","extradiscountrule"="extraDiscountRule"})
*/
class priceRule{
/**
*
* #Id #Column(type="integer")
* #GeneratedValue(strategy="AUTO")
*/
private $id;
/**
*
* #ManyToOne(targetEntity="contract",inversedBy="availibilityRules")
* #JoinColumn("contract_id",referencedColumnName="id")
*/
private $contract;
}
discountrule.php
namespace Entities;
/**
* #Entity
*
*
*/
class discountRule extends priceRule {
/**
*
* #Id #Column(type="integer")
* #GeneratedValue(strategy="AUTO")
*/
private $id;
public function calculatePrice(){
// calculate new price
}
}
extradiscountrule.php
namespace Entities;
/**
* #Entity
*
*
*/
class extraDiscountRule extends priceRule {
/**
*
* #Id #Column(type="integer")
* #GeneratedValue(strategy="AUTO")
*/
private $id;
public function calculate() {
// calculate new price
}
}
sampleusage.php
$contract=new Contract(1,1);
$discount=new discountRule();
$em->persist($discount);
$contract->addPriceRule($discount);
$em->persist($contract->getPriceRules());
$em->persist($contract);
$em->flush();
But when I try to add new rule to the contract I get error message (Fatal error: Uncaught exception 'Doctrine\ORM\Mapping\MappingException' with message 'Class Doctrine\Common\Collections\ArrayCollection is not a valid entity or mapped super class.)
What am I doing wrong ?

Answer 1

You may be missing an #MappedSuperclass on your PriceRule parent object
Refer to: Inheritance Mapping

Answer 2

I don't this is possible because an interface cannot define properties in a class, so you can't guarantee there will be properties for Doctrine to manipulate.
If you could provide more details on your entities I could help better.