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Mapping Classes to the ORM and ODM

Because of the non-intrusive design of Doctrine, it is possible to map PHP classes to both a relational database (with the Doctrine ORM) and MongoDB (with the Doctrine MongoDB ODM), or any other persistence layer that implements the Doctrine Persistence persistence interfaces.

Test Subject

For this cookbook entry, we need to define a class that can be persisted to both MySQL and MongoDB. We'll use a BlogPost as you may want to write some generic blogging functionality that has support for multiple Doctrine persistence layers:

1 <?php

namespace Documents\Blog;

class BlogPost
{
    public int $id;
    public string $title;
    public string $body;
}
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Mapping Information

Now we just need to provide the mapping information for the Doctrine persistence layers so they know how to consume the objects and persist them to the database.

ORM

First define the mapping for the ORM:

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namespace Documents\Blog;

use Documents\Blog\Repository\ORM\BlogPostRepository;
use Doctrine\ORM\Mapping as ORM;

#[ORM\Entity(repositoryClass: BlogPostRepository::class)]
class BlogPost
{
    #[ORM\Id]
    #[ORM\Column(type: 'integer')]
    #[ORM\GeneratedValue(strategy: 'AUTO')]
    public int $id;

    #[ORM\Column(type: 'string')]
    public string $title;

    #[ORM\Column(type: 'text')]
    public string $body;
}
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1 <?xml version="1.0" encoding="UTF-8"?>
<doctrine-mapping xmlns="http://doctrine-project.org/schemas/orm/doctrine-mapping"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://doctrine-project.org/schemas/orm/doctrine-mapping
                          http://www.doctrine-project.org/schemas/orm/doctrine-mapping.xsd">

    <entity name="Documents\Blog\BlogPost" repository-class="Documents\Blog\Repository\ORM\BlogPostRepository">
        <id name="id" type="int" />
        <field name="name" type="string" />
        <field name="email" type="text" />
    </entity>
</doctrine-mapping>
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Now you are able to persist the Documents\Blog\BlogPost with an instance of EntityManager:

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$blogPost = new BlogPost();
$blogPost->title = 'Hello World!';

$em->persist($blogPost);
$em->flush();
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You can find the blog post:

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$blogPost = $em->getRepository(BlogPost::class)->findOneBy(['title' => 'Hello World!']);
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MongoDB ODM

Now map the same class to the Doctrine MongoDB ODM:

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namespace Documents\Blog;

use Documents\Blog\Repository\ODM\BlogPostRepository;
use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;

#[ODM\Document(repositoryClass: BlogPostRepository::class)]
class BlogPost
{
    #[ODM\Id(type: 'int', strategy: 'INCREMENT')]
    public int $id;

    #[ODM\Field]
    public string $title;

    #[ODM\Field]
    public string $body;
}
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1 <?xml version="1.0" encoding="UTF-8"?>
<doctrine-mongo-mapping xmlns="http://doctrine-project.org/schemas/orm/doctrine-mapping"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://doctrine-project.org/schemas/orm/doctrine-mapping
                          http://www.doctrine-project.org/schemas/orm/doctrine-mapping.xsd">

    <document name="Documents\Blog\BlogPost" repository-class="Documents\Blog\Repository\ODM\BlogPostRepository">
        <id strategy="INCREMENT" type="int" />
        <field field-name="name" type="string" />
        <field field-name="email" type="text" />
    </document>
</doctrine-mongo-mapping>
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We use the INCREMENT strategy for the MongoDB ODM for compatibility with the ORM mapping. But you can also use the default AUTO strategy and store a generated MongoDB ObjectId as a string in the SQL database.

Now the same class is able to be persisted in the same way using an instance of DocumentManager:

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$blogPost = new BlogPost();
$blogPost->title = 'Hello World!';

$dm->persist($blogPost);
$dm->flush();
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You can find the blog post:

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$blogPost = $dm->getRepository(BlogPost::class)->findOneBy(['title' => 'Hello World!']);
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Repository Classes

You can implement the same repository interface for the ORM and MongoDB ODM easily, e.g. by creating BlogPostRepositoryInterface:

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// An Interface to ensure ORM and ODM Repository classes have the same methods implemented

namespace Documents\Blog\Repository;

use Documents\Blog\BlogPost;

interface BlogPostRepositoryInterface
{
    public function findPostById(int $id): ?BlogPost;
}
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Define repository methods required by the interface for the ORM:

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namespace Documents\Blog\Repository\ORM;

use Documents\Blog\Repository\BlogPostRepositoryInterface;
use Doctrine\ORM\EntityRepository;

class BlogPostRepository extends EntityRepository implements BlogPostRepositoryInterface
{
    public function findPostById(int $id): ?BlogPost
    {
        return $this->findOneBy(['id' => $id]);
    }
}
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Now define the same repository methods for the MongoDB ODM:

1 <?php

namespace Documents\Blog\Repository\ODM;

use Documents\Blog\Repository\BlogPostRepositoryInterface;
use Doctrine\ODM\MongoDB\Repository\DocumentRepository;

class BlogPostRepository extends DocumentRepository implements BlogPostRepositoryInterface
{
    public function findPostById(int $id): ?BlogPost
    {
        return $this->findOneBy(['id' => $id]);
    }
}
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As you can see the repositories are the same and the final returned data is the same vanilla PHP objects. The data is transparently injected to the objects for you automatically so you are not forced to extend some base class or shape your domain in any certain way for it to work with the Doctrine persistence layers.

If the same class is mapped to both the ORM and ODM, and you persist the instance in both, you will have two separate instances in memory. This is because the ORM and ODM are separate libraries and do not share the same object manager.

1	<?php namespace Documents\Blog; class BlogPost { public int $id; public string $title; public string $body; }
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1	<?php namespace Documents\Blog; use Documents\Blog\Repository\ORM\BlogPostRepository; use Doctrine\ORM\Mapping as ORM; #[ORM\Entity(repositoryClass: BlogPostRepository::class)] class BlogPost { #[ORM\Id] #[ORM\Column(type: 'integer')] #[ORM\GeneratedValue(strategy: 'AUTO')] public int $id; #[ORM\Column(type: 'string')] public string $title; #[ORM\Column(type: 'text')] public string $body; }
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1	<?xml version="1.0" encoding="UTF-8"?> <doctrine-mapping xmlns="http://doctrine-project.org/schemas/orm/doctrine-mapping" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://doctrine-project.org/schemas/orm/doctrine-mapping http://www.doctrine-project.org/schemas/orm/doctrine-mapping.xsd"> <entity name="Documents\Blog\BlogPost" repository-class="Documents\Blog\Repository\ORM\BlogPostRepository"> <id name="id" type="int" /> <field name="name" type="string" /> <field name="email" type="text" /> </entity> </doctrine-mapping>
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1	<?php $blogPost = new BlogPost(); $blogPost->title = 'Hello World!'; $em->persist($blogPost); $em->flush();
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1	<?php $blogPost = $em->getRepository(BlogPost::class)->findOneBy(['title' => 'Hello World!']);
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1	<?php $blogPost = $dm->getRepository(BlogPost::class)->findOneBy(['title' => 'Hello World!']);
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1	<?php // An Interface to ensure ORM and ODM Repository classes have the same methods implemented namespace Documents\Blog\Repository; use Documents\Blog\BlogPost; interface BlogPostRepositoryInterface { public function findPostById(int $id): ?BlogPost; }
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1	<?php namespace Documents\Blog\Repository\ORM; use Documents\Blog\Repository\BlogPostRepositoryInterface; use Doctrine\ORM\EntityRepository; class BlogPostRepository extends EntityRepository implements BlogPostRepositoryInterface { public function findPostById(int $id): ?BlogPost { return $this->findOneBy(['id' => $id]); } }
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Maintained

Unmaintained