Getting Started with Doctrine

Guide Assumptions

This guide is designed for beginners that haven't worked with Doctrine ORM before. There are some prerequisites for the tutorial that have to be installed:

• PHP (latest stable version)
• Composer Package Manager (Install Composer)

The code of this tutorial is available on Github.

What is Doctrine?

Doctrine ORM is an object-relational mapper (ORM) for PHP that provides transparent persistence for PHP objects. It uses the Data Mapper pattern at the heart, aiming for a complete separation of your domain/business logic from the persistence in a relational database management system.

The benefit of Doctrine for the programmer is the ability to focus on the object-oriented business logic and worry about persistence only as a secondary problem. This doesn't mean persistence is downplayed by Doctrine 2, however it is our belief that there are considerable benefits for object-oriented programming if persistence and entities are kept separated.

An Example Model: Bug Tracker

For this Getting Started Guide for Doctrine we will implement the Bug Tracker domain model from the Zend_Db_Table documentation. Reading their documentation we can extract the requirements:

• A Bug has a description, creation date, status, reporter and engineer
• A Bug can occur on different Products (platforms)
• A Product has a name.
• Bug reporters and engineers are both Users of the system.
• A User can create new Bugs.
• The assigned engineer can close a Bug.
• A User can see all their reported or assigned Bugs.
• Bugs can be paginated through a list-view.

Project Setup

Create a new empty folder for this tutorial project, for example doctrine2-tutorial and create a new file composer.json inside that directory with the following contents:

{
    "require": {
        "doctrine/orm": "^3",
        "doctrine/dbal": "^4",
        "symfony/cache": "^7"
    },
    "autoload": {
        "psr-0": {"": "src/"}
    }
}

Install Doctrine using the Composer Dependency Management tool, by calling:

$ composer install

This will install the packages Doctrine Common, Doctrine DBAL, Doctrine ORM, into the vendor directory.

Add the following directories:

doctrine2-tutorial
|-- config
|   `-- xml
`-- src

Obtaining the EntityManager

Doctrine's public interface is through the EntityManager. This class provides access points to the complete lifecycle management for your entities, and transforms entities from and back to persistence. You have to configure and create it to use your entities with Doctrine ORM. I will show the configuration steps and then discuss them step by step:

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<?php
// bootstrap.php
use Doctrine\DBAL\DriverManager;
use Doctrine\ORM\EntityManager;
use Doctrine\ORM\ORMSetup;

require_once "vendor/autoload.php";

// Create a simple "default" Doctrine ORM configuration for Attributes
$config = ORMSetup::createAttributeMetadataConfiguration(
    paths: [__DIR__ . '/src'],
    isDevMode: true,
);
// or if you prefer XML
// $config = ORMSetup::createXMLMetadataConfiguration(
//    paths: [__DIR__ . '/config/xml'],
//    isDevMode: true,
//);

// configuring the database connection
$connection = DriverManager::getConnection([
    'driver' => 'pdo_sqlite',
    'path' => __DIR__ . '/db.sqlite',
], $config);

// obtaining the entity manager
$entityManager = new EntityManager($connection, $config);
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The require_once statement sets up the class autoloading for Doctrine and its dependencies using Composer's autoloader.

The second block consists of the instantiation of the ORM Configuration object using the ORMSetup helper. It assumes a bunch of defaults that you don't have to bother about for now. You can read up on the configuration details in the reference chapter on configuration.

The third block shows the configuration options required to connect to a database. In this case, we'll use a file-based SQLite database. All the configuration options for all the shipped drivers are given in the DBAL Configuration section of the manual.

The last block shows how the EntityManager is obtained from a factory method.

Generating the Database Schema

Doctrine has a command-line interface that allows you to access the SchemaTool, a component that can generate a relational database schema based entirely on the defined entity classes and their metadata. For this tool to work, you need to create an executable console script as described in the tools chapter.

If you created the bootstrap.php file as described in the previous section, that script could look like this:

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#!/usr/bin/env php
<?php
// bin/doctrine

use Doctrine\ORM\Tools\Console\ConsoleRunner;
use Doctrine\ORM\Tools\Console\EntityManagerProvider\SingleManagerProvider;

// Adjust this path to your actual bootstrap.php
require __DIR__ . 'path/to/your/bootstrap.php';

ConsoleRunner::run(
    new SingleManagerProvider($entityManager)
);
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In the following examples, we will assume that this script has been created as bin/doctrine.

$ php bin/doctrine orm:schema-tool:create

Since we haven't added any entity metadata in src yet, you'll see a message stating "No Metadata Classes to process." In the next section, we'll create a Product entity along with the corresponding metadata, and run this command again.

Note that as you modify your entities' metadata during the development process, you'll need to update your database schema to stay in sync with the metadata. You can easily recreate the database using the following commands:

$ php bin/doctrine orm:schema-tool:drop --force
$ php bin/doctrine orm:schema-tool:create

Or you can use the update functionality:

$ php bin/doctrine orm:schema-tool:update --force

The updating of databases uses a diff algorithm for a given database schema. This is a cornerstone of the Doctrine\DBAL package, which can even be used without the Doctrine ORM package.

Starting with the Product Entity

We start with the simplest entity, the Product. Create a src/Product.php file to contain the Product entity definition:

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<?php
// src/Product.php
class Product
{
    private int|null $id = null;
    private string $name;
}
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When creating entity classes, all of the fields should be private.

Use protected when strictly needed and very rarely if not ever public.

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<?php
class User
{
    private $username;
    private $passwordHash;
    private $bans;

    public function getUsername(): string
    {
        return $this->username;
    }

    public function setUsername(string $username): void
    {
        $this->username = $username;
    }

    public function getPasswordHash(): string
    {
        return $this->passwordHash;
    }

    public function setPasswordHash(string $passwordHash): void
    {
        $this->passwordHash = $passwordHash;
    }

    public function getBans(): array
    {
        return $this->bans;
    }

    public function addBan(Ban $ban): void
    {
        $this->bans[] = $ban;
    }
}
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<?php
class User
{
    private $banned;
    private $username;
    private $passwordHash;
    private $bans;

    public function toNickname(): string
    {
        return $this->username;
    }

    public function authenticate(string $password, callable $checkHash): bool
    {
        return $checkHash($password, $this->passwordHash) && ! $this->hasActiveBans();
    }

    public function changePassword(string $password, callable $hash): void
    {
        $this->passwordHash = $hash($password);
    }

    public function ban(\DateInterval $duration): void
    {
        assert($duration->invert !== 1);

        $this->bans[] = new Ban($this);
    }
}
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<?php
class User
{
    public function updateFromProfile(ProfileEditingDTO $profileFormDTO): void
    {
        // ...
    }

    public static function createFromRegistration(UserRegistrationDTO $registrationDTO): self
    {
        // ...
    }
}
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<?php
// src/Product.php

use Doctrine\ORM\Mapping as ORM;

#[ORM\Entity]
#[ORM\Table(name: 'products')]
class Product
{
    #[ORM\Id]
    #[ORM\Column(type: 'integer')]
    #[ORM\GeneratedValue]
    private int|null $id = null;
    #[ORM\Column(type: 'string')]
    private string $name;

    // .. (other code)
}
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<!-- config/xml/Product.dcm.xml -->
<doctrine-mapping xmlns="http://doctrine-project.org/schemas/orm/doctrine-mapping"
                  xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
                  xsi:schemaLocation="http://doctrine-project.org/schemas/orm/doctrine-mapping
                                      https://www.doctrine-project.org/schemas/orm/doctrine-mapping.xsd">

      <entity name="Product" table="products">
          <id name="id" type="integer">
              <generator strategy="AUTO" />
          </id>

          <field name="name" type="string" />
      </entity>
</doctrine-mapping>
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$ php bin/doctrine orm:schema-tool:update --force --dump-sql

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<?php
// create_product.php <name>
require_once "bootstrap.php";

$newProductName = $argv[1];

$product = new Product();
$product->setName($newProductName);

$entityManager->persist($product);
$entityManager->flush();

echo "Created Product with ID " . $product->getId() . "\n";
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$ php create_product.php ORM
$ php create_product.php DBAL

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<?php
// list_products.php
require_once "bootstrap.php";

$productRepository = $entityManager->getRepository('Product');
$products = $productRepository->findAll();

foreach ($products as $product) {
    echo sprintf("-%s\n", $product->getName());
}
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<?php
// show_product.php <id>
require_once "bootstrap.php";

$id = $argv[1];
$product = $entityManager->find('Product', $id);

if ($product === null) {
    echo "No product found.\n";
    exit(1);
}

echo sprintf("-%s\n", $product->getName());
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<?php
// update_product.php <id> <new-name>
require_once "bootstrap.php";

$id = $argv[1];
$newName = $argv[2];

$product = $entityManager->find('Product', $id);

if ($product === null) {
    echo "Product $id does not exist.\n";
    exit(1);
}

$product->setName($newName);

$entityManager->flush();
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Adding Bug and User Entities

We continue with the bug tracker example by creating the Bug and User classes. We'll store them in src/Bug.php and src/User.php, respectively.

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<?php
// src/Bug.php

use Doctrine\ORM\Mapping as ORM;

#[ORM\Entity]
#[ORM\Table(name: 'bugs')]
class Bug
{
    #[ORM\Id]
    #[ORM\Column(type: 'integer')]
    #[ORM\GeneratedValue]
    private int|null $id;

    #[ORM\Column(type: 'string')]
    private string $description;

    #[ORM\Column(type: 'datetime')]
    private DateTime $created;

    #[ORM\Column(type: 'string')]
    private string $status;

    public function getId(): int|null
    {
        return $this->id;
    }

    public function getDescription(): string
    {
        return $this->description;
    }

    public function setDescription(string $description): void
    {
        $this->description = $description;
    }

    public function setCreated(DateTime $created)
    {
        $this->created = $created;
    }

    public function getCreated(): DateTime
    {
        return $this->created;
    }

    public function setStatus($status): void
    {
        $this->status = $status;
    }

    public function getStatus():string
    {
        return $this->status;
    }
}
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<?php
// src/User.php

use Doctrine\ORM\Mapping as ORM;

#[ORM\Entity]
#[ORM\Table(name: 'users')]
class User
{
    /** @var int */
    #[ORM\Id]
    #[ORM\GeneratedValue]
    #[ORM\Column(type: 'integer')]
    private int|null $id = null;

    /** @var string */
    #[ORM\Column(type: 'string')]
    private string $name;

    public function getId(): int|null
    {
        return $this->id;
    }

    public function getName(): string
    {
        return $this->name;
    }

    public function setName(string $name): void
    {
        $this->name = $name;
    }
}
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All of the properties we've seen so far are of simple types (integer, string, and datetime). But now, we'll add properties that will store objects of specific entity types in order to model the relationships between different entities.

At the database level, relationships between entities are represented by foreign keys. But with Doctrine, you'll never have to (and never should) work with the foreign keys directly. You should only work with objects that represent foreign keys through their own identities.

For every foreign key you either have a Doctrine ManyToOne or OneToOne association. On the inverse sides of these foreign keys you can have OneToMany associations. Obviously you can have ManyToMany associations that connect two tables with each other through a join table with two foreign keys.

Now that you know the basics about references in Doctrine, we can extend the domain model to match the requirements:

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<?php
// src/Bug.php

use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;

class Bug
{
    // ... (previous code)

    /** @var Collection<int, Product> */
    private Collection $products;

    public function __construct()
    {
        $this->products = new ArrayCollection();
    }
}
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<?php
// src/User.php
use Doctrine\Common\Collections\ArrayCollection;

class User
{
    // ... (previous code)

    /** @var Collection<int, Bug> */
    private Collection $reportedBugs;
    /** @var Collection<int, Bug> */
    private Collection $assignedBugs;

    public function __construct()
    {
        $this->reportedBugs = new ArrayCollection();
        $this->assignedBugs = new ArrayCollection();
    }
}
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Because we only work with collections for the references we must be careful to implement a bidirectional reference in the domain model. The concept of owning or inverse side of a relation is central to this notion and should always be kept in mind. The following assumptions are made about relations and have to be followed to be able to work with Doctrine ORM. These assumptions are not unique to Doctrine ORM but are best practices in handling database relations and Object-Relational Mapping.

• In a one-to-one relation, the entity holding the foreign key of the related entity on its own database table is always the owning side of the relation.
• In a many-to-one relation, the Many-side is the owning side by default because it holds the foreign key. Accordingly, the One-side is the inverse side by default.
• In a many-to-one relation, the One-side can only be the owning side if the relation is implemented as a ManyToMany with a join table, and the One-side is restricted to allow only UNIQUE values per database constraint.
• In a many-to-many relation, both sides can be the owning side of the relation. However, in a bi-directional many-to-many relation, only one side is allowed to be the owning side.
• Changes to Collections are saved or updated, when the entity on the owning side of the collection is saved or updated.
• Saving an Entity at the inverse side of a relation never triggers a persist operation to changes to the collection.

In the case of Users and Bugs we have references back and forth to the assigned and reported bugs from a user, making this relation bi-directional. We have to change the code to ensure consistency of the bi-directional reference:

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<?php
// src/Bug.php
class Bug
{
    // ... (previous code)

    private User $engineer;
    private User $reporter;

    public function setEngineer(User $engineer): void
    {
        $engineer->assignedToBug($this);
        $this->engineer = $engineer;
    }

    public function setReporter(User $reporter): void
    {
        $reporter->addReportedBug($this);
        $this->reporter = $reporter;
    }

    public function getEngineer(): User
    {
        return $this->engineer;
    }

    public function getReporter(): User
    {
        return $this->reporter;
    }
}
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<?php
// src/User.php
class User
{
    // ... (previous code)

    /** @var Collection<int, Bug> */
    private Collection $reportedBugs;
    /** @var Collection<int, Bug> */
    private Collection $assignedBugs;

    public function addReportedBug(Bug $bug): void
    {
        $this->reportedBugs[] = $bug;
    }

    public function assignedToBug(Bug $bug): void
    {
        $this->assignedBugs[] = $bug;
    }
}
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I chose to name the inverse methods in past-tense, which should indicate that the actual assigning has already taken place and the methods are only used for ensuring consistency of the references. This approach is my personal preference, you can choose whatever method to make this work.

You can see from User#addReportedBug() and User#assignedToBug() that using this method in userland alone would not add the Bug to the collection of the owning side in Bug#reporter or Bug#engineer. Using these methods and calling Doctrine for persistence would not update the Collections' representation in the database.

Only using Bug#setEngineer() or Bug#setReporter() correctly saves the relation information.

The Bug#reporter and Bug#engineer properties are Many-To-One relations, which point to a User. In a normalized relational model, the foreign key is saved on the Bug's table, hence in our object-relation model the Bug is at the owning side of the relation. You should always make sure that the use-cases of your domain model should drive which side is an inverse or owning one in your Doctrine mapping. In our example, whenever a new bug is saved or an engineer is assigned to the bug, we don't want to update the User to persist the reference, but the Bug. This is the case with the Bug being at the owning side of the relation.

Bugs reference Products by a uni-directional ManyToMany relation in the database that points from Bugs to Products.

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<?php
// src/Bug.php
class Bug
{
    // ... (previous code)

    /** @var Collection<int, Product> */
    private Collection $products;

    public function assignToProduct(Product $product): void
    {
        $this->products[] = $product;
    }

    /** @return Collection<int, Product> */
    public function getProducts(): Collection
    {
        return $this->products;
    }
}
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We are now finished with the domain model given the requirements. Lets add metadata mappings for the Bug entity, as we did for the Product before:

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<?php
// src/Bug.php

use DateTime;
use Doctrine\ORM\Mapping as ORM;

#[ORM\Entity]
#[ORM\Table(name: 'bugs')]
class Bug
{
    #[ORM\Id]
    #[ORM\Column(type: 'integer')]
    #[ORM\GeneratedValue]
    private int|null $id = null;

    #[ORM\Column(type: 'string')]
    private string $description;

    #[ORM\Column(type: 'datetime')]
    private DateTime $created;

    #[ORM\Column(type: 'string')]
    private string $status;

    #[ORM\ManyToOne(targetEntity: User::class, inversedBy: 'assignedBugs')]
    private User|null $engineer = null;

    #[ORM\ManyToOne(targetEntity: User::class, inversedBy: 'reportedBugs')]
    private User|null $reporter;

    /** @var Collection<int, Product> */
    #[ORM\ManyToMany(targetEntity: Product::class)]
    private Collection $products;

    // ... (other code)
}
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<!-- config/xml/Bug.dcm.xml -->
<doctrine-mapping xmlns="http://doctrine-project.org/schemas/orm/doctrine-mapping"
                  xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
                  xsi:schemaLocation="http://doctrine-project.org/schemas/orm/doctrine-mapping
                                      https://www.doctrine-project.org/schemas/orm/doctrine-mapping.xsd">

    <entity name="Bug" table="bugs">
        <id name="id" type="integer">
            <generator strategy="AUTO" />
        </id>

        <field name="description" type="text" />
        <field name="created" type="datetime" />
        <field name="status" type="string" />

        <many-to-one target-entity="User" field="reporter" inversed-by="reportedBugs" />
        <many-to-one target-entity="User" field="engineer" inversed-by="assignedBugs" />

        <many-to-many target-entity="Product" field="products" />
    </entity>
</doctrine-mapping>
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Here we have the entity, id and primitive type definitions. For the "created" field we have used the datetime type, which translates the YYYY-mm-dd HH:mm:ss database format into a PHP DateTime instance and back.

After the field definitions, the two qualified references to the user entity are defined. They are created by the ManyToOne attribute. The class name of the related entity has to be specified with the targetEntity parameter, which is enough information for the database mapper to access the foreign table. Since reporter and engineer are on the owning side of a bi-directional relation, we also have to specify the inversedBy parameter. They have to point to the field names on the inverse side of the relationship. We will see in the next example that the inversedBy parameter has a counterpart mappedBy which makes that the inverse side.

The last definition is for the Bug#products collection. It holds all products where the specific bug occurs. Again you have to define the targetEntity and field parameters on the ManyToMany attribute.

Finally, we'll add metadata mappings for the User entity.

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<?php
// src/User.php

use Doctrine\ORM\Mapping as ORM;

#[ORM\Entity]
#[ORM\Table(name: 'users')]
class User
{
    #[ORM\Id]
    #[ORM\GeneratedValue]
    #[ORM\Column(type: 'integer')]
    private int|null $id = null;

    #[ORM\Column(type: 'string')]
    private string $name;

    /** @var Collection<int, Bug> An ArrayCollection of Bug objects. */
    #[ORM\OneToMany(targetEntity: Bug::class, mappedBy: 'reporter')]
    private Collection $reportedBugs;

    /** @var Collection<int,Bug> An ArrayCollection of Bug objects. */
    #[ORM\OneToMany(targetEntity: Bug::class, mappedBy: 'engineer')]
    private $assignedBugs;

    // .. (other code)
}
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<!-- config/xml/User.dcm.xml -->
<doctrine-mapping xmlns="http://doctrine-project.org/schemas/orm/doctrine-mapping"
                  xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
                  xsi:schemaLocation="http://doctrine-project.org/schemas/orm/doctrine-mapping
                                      https://www.doctrine-project.org/schemas/orm/doctrine-mapping.xsd">

     <entity name="User" table="users">
         <id name="id" type="integer">
             <generator strategy="AUTO" />
         </id>

         <field name="name" type="string" />

         <one-to-many target-entity="Bug" field="reportedBugs" mapped-by="reporter" />
         <one-to-many target-entity="Bug" field="assignedBugs" mapped-by="engineer" />
     </entity>
</doctrine-mapping>
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Here are some new things to mention about the one-to-many tags. Remember that we discussed about the inverse and owning side. Now both reportedBugs and assignedBugs are inverse relations, which means the join details have already been defined on the owning side. Therefore we only have to specify the property on the Bug class that holds the owning sides.

Update your database schema by running:

$ php bin/doctrine orm:schema-tool:update --force

Implementing more Requirements

So far, we've seen the most basic features of the metadata definition language. To explore additional functionality, let's first create new User entities:

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<?php
// create_user.php
require_once "bootstrap.php";

$newUsername = $argv[1];

$user = new User();
$user->setName($newUsername);

$entityManager->persist($user);
$entityManager->flush();

echo "Created User with ID " . $user->getId() . "\n";
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Now call:

$ php create_user.php beberlei

We now have the necessary data to create a new Bug entity:

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<?php
// create_bug.php <reporter-id> <engineer-id> <product-ids>
require_once "bootstrap.php";

$reporterId = $argv[1];
$engineerId = $argv[2];
$productIds = explode(",", $argv[3]);

$reporter = $entityManager->find("User", $reporterId);
$engineer = $entityManager->find("User", $engineerId);
if (!$reporter || !$engineer) {
    echo "No reporter and/or engineer found for the given id(s).\n";
    exit(1);
}

$bug = new Bug();
$bug->setDescription("Something does not work!");
$bug->setCreated(new DateTime("now"));
$bug->setStatus("OPEN");

foreach ($productIds as $productId) {
    $product = $entityManager->find("Product", $productId);
    $bug->assignToProduct($product);
}

$bug->setReporter($reporter);
$bug->setEngineer($engineer);

$entityManager->persist($bug);
$entityManager->flush();

echo "Your new Bug Id: ".$bug->getId()."\n";
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Since we only have one user and product, probably with the ID of 1, we can call this script as follows:

$ php create_bug.php 1 1 1

See how simple it is to relate a Bug, Reporter, Engineer and Products? Also recall that thanks to the UnitOfWork pattern, Doctrine will detect these relations and update all of the modified entities in the database automatically when flush() is called.

Queries for Application Use-Cases

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<?php
// list_bugs.php
require_once "bootstrap.php";

$dql = "SELECT b, e, r FROM Bug b JOIN b.engineer e JOIN b.reporter r ORDER BY b.created DESC";

$query = $entityManager->createQuery($dql);
$query->setMaxResults(30);
$bugs = $query->getResult();

foreach ($bugs as $bug) {
    echo $bug->getDescription()." - ".$bug->getCreated()->format('d.m.Y')."\n";
    echo "    Reported by: ".$bug->getReporter()->getName()."\n";
    echo "    Assigned to: ".$bug->getEngineer()->getName()."\n";
    foreach ($bug->getProducts() as $product) {
        echo "    Platform: ".$product->getName()."\n";
    }
    echo "\n";
}
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Something does not work! - 02.04.2010
    Reported by: beberlei
    Assigned to: beberlei
    Platform: My Product

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<?php
// list_bugs_array.php
require_once "bootstrap.php";

$dql = "SELECT b, e, r, p FROM Bug b JOIN b.engineer e ".
       "JOIN b.reporter r JOIN b.products p ORDER BY b.created DESC";
$query = $entityManager->createQuery($dql);
$bugs = $query->getArrayResult();

foreach ($bugs as $bug) {
    echo $bug['description'] . " - " . $bug['created']->format('d.m.Y')."\n";
    echo "    Reported by: ".$bug['reporter']['name']."\n";
    echo "    Assigned to: ".$bug['engineer']['name']."\n";
    foreach ($bug['products'] as $product) {
        echo "    Platform: ".$product['name']."\n";
    }
    echo "\n";
}
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<?php
// show_bug.php <id>
require_once "bootstrap.php";

$theBugId = $argv[1];

$bug = $entityManager->find("Bug", (int)$theBugId);

echo "Bug: ".$bug->getDescription()."\n";
echo "Engineer: ".$bug->getEngineer()->getName()."\n";
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$ php show_bug.php 1
Bug: Something does not work!
Engineer: beberlei

Dashboard of the User

For the next use-case we want to retrieve the dashboard view, a list of all open bugs the user reported or was assigned to. This will be achieved using DQL again, this time with some WHERE clauses and usage of bound parameters:

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<?php
// dashboard.php <user-id>
require_once "bootstrap.php";

$theUserId = $argv[1];

$dql = "SELECT b, e, r FROM Bug b JOIN b.engineer e JOIN b.reporter r ".
       "WHERE b.status = 'OPEN' AND (e.id = ?1 OR r.id = ?1) ORDER BY b.created DESC";

$myBugs = $entityManager->createQuery($dql)
                        ->setParameter(1, $theUserId)
                        ->setMaxResults(15)
                        ->getResult();

echo "You have created or assigned to " . count($myBugs) . " open bugs:\n\n";

foreach ($myBugs as $bug) {
    echo $bug->getId() . " - " . $bug->getDescription()."\n";
}
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Number of Bugs

Until now we only retrieved entities or their array representation. Doctrine also supports the retrieval of non-entities through DQL. These values are called "scalar result values" and may even be aggregate values using COUNT, SUM, MIN, MAX or AVG functions.

We will need this knowledge to retrieve the number of open bugs grouped by product:

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<?php
// products.php
require_once "bootstrap.php";

$dql = "SELECT p.id, p.name, count(b.id) AS openBugs FROM Bug b ".
       "JOIN b.products p WHERE b.status = 'OPEN' GROUP BY p.id";
$productBugs = $entityManager->createQuery($dql)->getScalarResult();

foreach ($productBugs as $productBug) {
    echo $productBug['name']." has " . $productBug['openBugs'] . " open bugs!\n";
}
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Updating Entities

There is a single use-case missing from the requirements, Engineers should be able to close a bug. This looks like:

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<?php
// src/Bug.php

class Bug
{
    public function close()
    {
        $this->status = "CLOSE";
    }
}
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<?php
// close_bug.php <bug-id>
require_once "bootstrap.php";

$theBugId = $argv[1];

$bug = $entityManager->find("Bug", (int)$theBugId);
$bug->close();

$entityManager->flush();
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When retrieving the Bug from the database it is inserted into the IdentityMap inside the UnitOfWork of Doctrine. This means your Bug with exactly this id can only exist once during the whole request no matter how often you call EntityManager#find(). It even detects entities that are hydrated using DQL and are already present in the Identity Map.

When flush is called the EntityManager loops over all the entities in the identity map and performs a comparison between the values originally retrieved from the database and those values the entity currently has. If at least one of these properties is different the entity is scheduled for an UPDATE against the database. Only the changed columns are updated, which offers a pretty good performance improvement compared to updating all the properties.

Entity Repositories

For now we have not discussed how to separate the Doctrine query logic from your model. In Doctrine 1 there was the concept of Doctrine_Table instances for this separation. The similar concept in Doctrine2 is called Entity Repositories, integrating the repository pattern at the heart of Doctrine.

Every Entity uses a default repository by default and offers a bunch of convenience methods that you can use to query for instances of that Entity. Take for example our Product entity. If we wanted to Query by name, we can use:

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<?php
$product = $entityManager->getRepository('Product')
                         ->findOneBy(array('name' => $productName));
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The method findOneBy() takes an array of fields or association keys and the values to match against.

If you want to find all entities matching a condition you can use findBy(), for example querying for all closed bugs:

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<?php
$bugs = $entityManager->getRepository('Bug')
                      ->findBy(array('status' => 'CLOSED'));

foreach ($bugs as $bug) {
    // do stuff
}
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Compared to DQL these query methods are falling short of functionality very fast. Doctrine offers you a convenient way to extend the functionalities of the default EntityRepository and put all the specialized DQL query logic on it. For this you have to create a subclass of Doctrine\ORM\EntityRepository, in our case a BugRepository and group all the previously discussed query functionality in it:

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<?php
// src/BugRepository.php

use Doctrine\ORM\EntityRepository;

class BugRepository extends EntityRepository
{
    public function getRecentBugs($number = 30)
    {
        $dql = "SELECT b, e, r FROM Bug b JOIN b.engineer e JOIN b.reporter r ORDER BY b.created DESC";

        $query = $this->getEntityManager()->createQuery($dql);
        $query->setMaxResults($number);
        return $query->getResult();
    }

    public function getRecentBugsArray($number = 30)
    {
        $dql = "SELECT b, e, r, p FROM Bug b JOIN b.engineer e ".
               "JOIN b.reporter r JOIN b.products p ORDER BY b.created DESC";
        $query = $this->getEntityManager()->createQuery($dql);
        $query->setMaxResults($number);
        return $query->getArrayResult();
    }

    public function getUsersBugs($userId, $number = 15)
    {
        $dql = "SELECT b, e, r FROM Bug b JOIN b.engineer e JOIN b.reporter r ".
               "WHERE b.status = 'OPEN' AND e.id = ?1 OR r.id = ?1 ORDER BY b.created DESC";

        return $this->getEntityManager()->createQuery($dql)
                             ->setParameter(1, $userId)
                             ->setMaxResults($number)
                             ->getResult();
    }

    public function getOpenBugsByProduct()
    {
        $dql = "SELECT p.id, p.name, count(b.id) AS openBugs FROM Bug b ".
               "JOIN b.products p WHERE b.status = 'OPEN' GROUP BY p.id";
        return $this->getEntityManager()->createQuery($dql)->getScalarResult();
    }
}
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To be able to use this query logic through $this->getEntityManager()->getRepository('Bug') we have to adjust the metadata slightly.

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<?php

use Doctrine\ORM\Mapping as ORM;

#[ORM\Entity(repositoryClass: BugRepository::class)]
#[ORM\Table(name: 'bugs')]
class Bug
{
    // ...
}
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<doctrine-mapping xmlns="http://doctrine-project.org/schemas/orm/doctrine-mapping"
      xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://doctrine-project.org/schemas/orm/doctrine-mapping
                          https://www.doctrine-project.org/schemas/orm/doctrine-mapping.xsd">

      <entity name="Bug" table="bugs" repository-class="BugRepository">

      </entity>
</doctrine-mapping>
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Now we can remove our query logic in all the places and instead use them through the EntityRepository. As an example here is the code of the first use case "List of Bugs":

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<?php
// list_bugs_repository.php
require_once "bootstrap.php";

$bugs = $entityManager->getRepository('Bug')->getRecentBugs();

foreach ($bugs as $bug) {
    echo $bug->getDescription()." - ".$bug->getCreated()->format('d.m.Y')."\n";
    echo "    Reported by: ".$bug->getReporter()->getName()."\n";
    echo "    Assigned to: ".$bug->getEngineer()->getName()."\n";
    foreach ($bug->getProducts() as $product) {
        echo "    Platform: ".$product->getName()."\n";
    }
    echo "\n";
}
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Using EntityRepositories you can avoid coupling your model with specific query logic. You can also re-use query logic easily throughout your application.

The method count() takes an array of fields or association keys and the values to match against. This provides you with a convenient and lightweight way to count a resultset when you don't need to deal with it:

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<?php
$productCount = $entityManager->getRepository(Product::class)
                         ->count(['name' => $productName]);
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Conclusion

This tutorial is over here, I hope you had fun. Additional content will be added to this tutorial incrementally, topics will include:

• More on Association Mappings
• Lifecycle Events triggered in the UnitOfWork
• Ordering of Collections

Additional details on all the topics discussed here can be found in the respective manual chapters.