Doctrine Inheritance: Discriminator from Entity attribute and not table column?

Using Doctrine2 inheritance, I want a slight variation so that the discriminator is not based on a column (from the mapped table), but rather on an Entity's attribute. The code would look like this:

(p.s I know there's nothing like @DiscriminatorAttribute in Doctrine, I'm just asking about an eventual workaround to "implement it")

<?php

namespace AppEntity;

use DoctrineORMMapping as ORM;

/**
* @Entity
* @InheritanceType("SINGLE_TABLE")
* @DiscriminatorAttribute(name="shopType", type="string")
* @DiscriminatorMap("local" = "LocalShop", "foreign" = "ForeignShop")
*/
class Shop

const TYPE_LOCAL="local";
const TYPE_FOREIGN="foreign";

protected $shopType;
// ...


/**
* @Entity
*/
class LocalShop extends Shop

public function __construct()

$this->shopType=Shop::TYPE_LOCAL;

// ...

/**
* @Entity
*/
class ForeignShop extends Shop

public function __construct()

$this->shopType=Shop::TYPE_FOREIGN;

// ...



1 Answer
1

Given the fact that shopType is a rather static property (in the sense that it will always be the same for all instances of a class) you can simply define the shopType as default for the property, and use the existing column as discriminator column:

shopType

shopType

<?php

namespace AppEntity;

use DoctrineORMMapping as ORM;

/**
* @ORMEntity
* @ORMInheritanceType("SINGLE_TABLE")
* @ORMDiscriminatorColumn(name="shopType", type="string")
* @ORMDiscriminatorMap("local" = "LocalShop", "foreign" = "ForeignShop")
*/
class Shop

protected const TYPE_LOCAL = 'local';
protected const TYPE_FOREIGN = 'foreign';

// ...


/**
* @Entity
*/
class LocalShop extends Shop

protected $shopType = Shop::TYPE_LOCAL;
// ...


/**
* @Entity
*/
class ForeignShop extends Shop

protected $shopType = Shop::TYPE_FOREIGN;
// ...



Doctrine's hydrators will take a new instance of your class, which gets instantiated with all default values applied, and then write all the fetched information from the database to the mapped properties.

Since your property has the expected value in the defaults, and is not mapped, its correct default value will not be changed by the hydration process and have the expected value, even when fetched from the database.

In that process, the constructor is not called (Entities are either cloned or produced by Reflection's newInstanceWithoutConstructor), which is why the original code did not work.

Thanks for contributing an answer to Stack Overflow!

But avoid …

To learn more, see our tips on writing great answers.

Required, but never shown

Required, but never shown

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.