我需要一个使用“多态关联”的学说 2 的具体代码示例。让我澄清一下自己。我有一个名为 Contract 的实体，一个合同可以有许多价格规则，这些价格规则可以是不同类型的类并存在于不同的表中。我想这是多态关联的原因还是我错了？
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
}
}
未来可能会有新的价格规则类型，那么如何将这些规则与主要实体关联并保存在单独的表格中？
更新：
这是我的新代码：
合同.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;
}
}
价格规则.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;
}
折扣规则.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
}
}
示例使用.php
$contract=new Contract(1,1);
$discount=new discountRule();
$em->persist($discount);
$contract->addPriceRule($discount);
$em->persist($contract->getPriceRules());
$em->persist($contract);
$em->flush();
但是当我尝试向合同中添加新规则时，我收到错误消息（致命错误：未捕获异常 'Doctrine\ORM\Mapping\MappingException' 并带有消息 'Class Doctrine\Common\Collections\ArrayCollection is not a valid entity or mapped super class .)
我究竟做错了什么 ？