Databases and the Doctrine ORM

Installing Doctrine

First, install Doctrine support via the orm Symfony pack, as well as the MakerBundle, which will help generate some code:

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$ composer require symfony/orm-pack
$ composer require --dev symfony/maker-bundle

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# .env (or override DATABASE_URL in .env.local to avoid committing your changes)

# customize this line!
DATABASE_URL="mysql://db_user:db_password@127.0.0.1:3306/db_name?serverVersion=8.0.37"

# to use mariadb:
# Before doctrine/dbal < 3.7
# DATABASE_URL="mysql://db_user:db_password@127.0.0.1:3306/db_name?serverVersion=mariadb-10.5.8"
# Since doctrine/dbal 3.7
# DATABASE_URL="mysql://db_user:db_password@127.0.0.1:3306/db_name?serverVersion=10.5.8-MariaDB"

# to use sqlite:
# DATABASE_URL="sqlite:///%kernel.project_dir%/var/app.db"

# to use postgresql:
# DATABASE_URL="postgresql://db_user:db_password@127.0.0.1:5432/db_name?serverVersion=12.19 (Debian 12.19-1.pgdg120+1)&charset=utf8"

# to use oracle:
# DATABASE_URL="oci8://db_user:db_password@127.0.0.1:1521/db_name"

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$ php bin/console doctrine:database:create

Creating an Entity Class

Suppose you're building an application where products need to be displayed. Without even thinking about Doctrine or databases, you already know that you need a Product object to represent those products.

You can use the make:entity command to create this class and any fields you need. The command will ask you some questions - answer them like done below:

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$ php bin/console make:entity

Class name of the entity to create or update:
> Product

New property name (press <return> to stop adding fields):
> name

Field type (enter ? to see all types) [string]:
> string

Field length [255]:
> 255

Can this field be null in the database (nullable) (yes/no) [no]:
> no

New property name (press <return> to stop adding fields):
> price

Field type (enter ? to see all types) [string]:
> integer

Can this field be null in the database (nullable) (yes/no) [no]:
> no

New property name (press <return> to stop adding fields):
>
(press enter again to finish)

Whoa! You now have a new src/Entity/Product.php file:

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// src/Entity/Product.php
namespace App\Entity;

use App\Repository\ProductRepository;
use Doctrine\ORM\Mapping as ORM;

#[ORM\Entity(repositoryClass: ProductRepository::class)]
class Product
{
    #[ORM\Id]
    #[ORM\GeneratedValue]
    #[ORM\Column]
    private ?int $id = null;

    #[ORM\Column(length: 255)]
    private ?string $name = null;

    #[ORM\Column]
    private ?int $price = null;

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

    // ... getter and setter methods
}

This class is called an "entity". And soon, you'll be able to save and query Product objects to a product table in your database. Each property in the Product entity can be mapped to a column in that table. This is usually done with attributes: the #[ORM\Column(...)] comments that you see above each property:

The make:entity command is a tool to make life easier. But this is your code: add/remove fields, add/remove methods or update configuration.

Doctrine supports a wide variety of field types, each with their own options. Check out the list of Doctrine mapping types in the Doctrine documentation. If you want to use XML instead of attributes, add type: xml and dir: '%kernel.project_dir%/config/doctrine' to the entity mappings in your config/packages/doctrine.yaml file.

Migrations: Creating the Database Tables/Schema

The Product class is fully-configured and ready to save to a product table. If you just defined this class, your database doesn't actually have the product table yet. To add it, you can leverage the DoctrineMigrationsBundle, which is already installed:

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$ php bin/console make:migration

If everything worked, you should see something like this:

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SUCCESS!

Next: Review the new migration "migrations/Version20211116204726.php"
Then: Run the migration with php bin/console doctrine:migrations:migrate

If you open this file, it contains the SQL needed to update your database! To run that SQL, execute your migrations:

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$ php bin/console doctrine:migrations:migrate

This command executes all migration files that have not already been run against your database. You should run this command on production when you deploy to keep your production database up-to-date.

Migrations & Adding more Fields

But what if you need to add a new field property to Product, like a description? You can edit the class to add the new property. But, you can also use make:entity again:

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$ php bin/console make:entity

Class name of the entity to create or update
> Product

New property name (press <return> to stop adding fields):
> description

Field type (enter ? to see all types) [string]:
> text

Can this field be null in the database (nullable) (yes/no) [no]:
> no

New property name (press <return> to stop adding fields):
>
(press enter again to finish)

This adds the new description property and getDescription() and setDescription() methods:

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// src/Entity/Product.php
  // ...
+  use Doctrine\DBAL\Types\Types;

  class Product
  {
      // ...

+     #[ORM\Column(type: Types::TEXT)]
+     private string $description;

      // getDescription() & setDescription() were also added
  }

The new property is mapped, but it doesn't exist yet in the product table. No problem! Generate a new migration:

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$ php bin/console make:migration

This time, the SQL in the generated file will look like this:

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ALTER TABLE product ADD description LONGTEXT NOT NULL

The migration system is smart. It compares all of your entities with the current state of the database and generates the SQL needed to synchronize them! Like before, execute your migrations:

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$ php bin/console doctrine:migrations:migrate

This will only execute the one new migration file, because DoctrineMigrationsBundle knows that the first migration was already executed earlier. Behind the scenes, it manages a migration_versions table to track this.

Each time you make a change to your schema, run these two commands to generate the migration and then execute it. Be sure to commit the migration files and execute them when you deploy.

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$ php bin/console make:entity --regenerate

Persisting Objects to the Database

It's time to save a Product object to the database! Let's create a new controller to experiment:

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$ php bin/console make:controller ProductController

Inside the controller, you can create a new Product object, set data on it, and save it:

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// src/Controller/ProductController.php
namespace App\Controller;

// ...
use App\Entity\Product;
use Doctrine\ORM\EntityManagerInterface;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;

class ProductController extends AbstractController
{
    #[Route('/product', name: 'create_product')]
    public function createProduct(EntityManagerInterface $entityManager): Response
    {
        $product = new Product();
        $product->setName('Keyboard');
        $product->setPrice(1999);
        $product->setDescription('Ergonomic and stylish!');

        // tell Doctrine you want to (eventually) save the Product (no queries yet)
        $entityManager->persist($product);

        // actually executes the queries (i.e. the INSERT query)
        $entityManager->flush();

        return new Response('Saved new product with id '.$product->getId());
    }
}

Try it out!

http://localhost:8000/product

Congratulations! You just created your first row in the product table. To prove it, you can query the database directly:

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$ php bin/console dbal:run-sql 'SELECT * FROM product'

# on Windows systems not using Powershell, run this command instead:
# php bin/console dbal:run-sql "SELECT * FROM product"

Take a look at the previous example in more detail:

• line 13 The EntityManagerInterface $entityManager argument tells Symfony to inject the Entity Manager service into the controller method. This object is responsible for saving objects to, and fetching objects from, the database.
• lines 15-18 In this section, you instantiate and work with the $product object like any other normal PHP object.
• line 21 The persist($product) call tells Doctrine to "manage" the $product object. This does not cause a query to be made to the database.
• line 24 When the flush() method is called, Doctrine looks through all of the objects that it's managing to see if they need to be persisted to the database. In this example, the $product object's data doesn't exist in the database, so the entity manager executes an INSERT query, creating a new row in the product table.

Whether you're creating or updating objects, the workflow is always the same: Doctrine is smart enough to know if it should INSERT or UPDATE your entity.

Validating Objects

The Symfony validator can reuse Doctrine metadata to perform some basic validation tasks. First, add or configure the auto_mapping option to define which entities should be introspected by Symfony to add automatic validation constraints.

Consider the following controller code:

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// src/Controller/ProductController.php
namespace App\Controller;

use App\Entity\Product;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;
use Symfony\Component\Validator\Validator\ValidatorInterface;
// ...

class ProductController extends AbstractController
{
    #[Route('/product', name: 'create_product')]
    public function createProduct(ValidatorInterface $validator): Response
    {
        $product = new Product();

        // ... update the product data somehow (e.g. with a form) ...

        $errors = $validator->validate($product);
        if (count($errors) > 0) {
            return new Response((string) $errors, 400);
        }

        // ...
    }
}

Although the Product entity doesn't define any explicit validation configuration, if the auto_mapping option includes it in the list of entities to introspect, Symfony will infer some validation rules for it and will apply them.

For example, given that the name property can't be null in the database, a NotNull constraint is added automatically to the property (if it doesn't contain that constraint already).

The following table summarizes the mapping between Doctrine metadata and the corresponding validation constraints added automatically by Symfony:

Because the Form component as well as API Platform internally use the Validator component, all your forms and web APIs will also automatically benefit from these automatic validation constraints.

This automatic validation is a nice feature to improve your productivity, but it doesn't replace the validation configuration entirely. You still need to add some validation constraints to ensure that data provided by the user is correct.

Fetching Objects from the Database

Fetching an object back out of the database is even easier. Suppose you want to be able to go to /product/1 to see your new product:

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// src/Controller/ProductController.php
namespace App\Controller;

use App\Entity\Product;
use Doctrine\ORM\EntityManagerInterface;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;
// ...

class ProductController extends AbstractController
{
    #[Route('/product/{id}', name: 'product_show')]
    public function show(EntityManagerInterface $entityManager, int $id): Response
    {
        $product = $entityManager->getRepository(Product::class)->find($id);

        if (!$product) {
            throw $this->createNotFoundException(
                'No product found for id '.$id
            );
        }

        return new Response('Check out this great product: '.$product->getName());

        // or render a template
        // in the template, print things with {{ product.name }}
        // return $this->render('product/show.html.twig', ['product' => $product]);
    }
}

Another possibility is to use the ProductRepository using Symfony's autowiring and injected by the dependency injection container:

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// src/Controller/ProductController.php
namespace App\Controller;

use App\Entity\Product;
use App\Repository\ProductRepository;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;
// ...

class ProductController extends AbstractController
{
    #[Route('/product/{id}', name: 'product_show')]
    public function show(ProductRepository $productRepository, int $id): Response
    {
        $product = $productRepository
            ->find($id);

        // ...
    }
}

Try it out!

http://localhost:8000/product/1

When you query for a particular type of object, you always use what's known as its "repository". You can think of a repository as a PHP class whose only job is to help you fetch entities of a certain class.

Once you have a repository object, you have many helper methods:

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$repository = $entityManager->getRepository(Product::class);

// look for a single Product by its primary key (usually "id")
$product = $repository->find($id);

// look for a single Product by name
$product = $repository->findOneBy(['name' => 'Keyboard']);
// or find by name and price
$product = $repository->findOneBy([
    'name' => 'Keyboard',
    'price' => 1999,
]);

// look for multiple Product objects matching the name, ordered by price
$products = $repository->findBy(
    ['name' => 'Keyboard'],
    ['price' => 'ASC']
);

// look for *all* Product objects
$products = $repository->findAll();

You can also add custom methods for more complex queries! More on that later in the Databases and the Doctrine ORM section.

Tip

When rendering an HTML page, the web debug toolbar at the bottom of the page will display the number of queries and the time it took to execute them:

If the number of database queries is too high, the icon will turn yellow to indicate that something may not be correct. Click on the icon to open the Symfony Profiler and see the exact queries that were executed. If you don't see the web debug toolbar, install the profiler Symfony pack by running this command: composer require --dev symfony/profiler-pack.

For more information, read the Symfony profiler documentation.

Automatically Fetching Objects (EntityValueResolver)

In many cases, you can use the EntityValueResolver to do the query for you automatically! You can simplify the controller to:

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// src/Controller/ProductController.php
namespace App\Controller;

use App\Entity\Product;
use App\Repository\ProductRepository;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;
// ...

class ProductController extends AbstractController
{
    #[Route('/product/{id}')]
    public function show(Product $product): Response
    {
        // use the Product!
        // ...
    }
}

That's it! The attribute uses the {id} from the route to query for the Product by the id column. If it's not found, a 404 error is thrown.

You can change this behavior by making the controller argument optional. In that case, no 404 is thrown automatically and you're free to handle the missing entity yourself:

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#[Route('/product/{id}')]
public function show(?Product $product): Response
{
    if (null === $product) {
        // run your own logic to return a custom response
    }

    // ...
}

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public function show(
    #[CurrentUser]
    #[MapEntity(disabled: true)]
    User $user
): Response {
    // User is not resolved by the EntityValueResolver
    // ...
}

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/**
 * Fetch via primary key because {id} is in the route.
 */
#[Route('/product/{id}')]
public function showByPk(Product $product): Response
{
}

/**
 * Perform a findOneBy() where the slug property matches {slug}.
 */
#[Route('/product/{slug:product}')]
public function showBySlug(Product $product): Response
{
}

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// src/Controller/ProductController.php
namespace App\Controller;

use App\Entity\Product;
use Symfony\Bridge\Doctrine\Attribute\MapEntity;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;
// ...

class ProductController extends AbstractController
{
    #[Route('/product/{slug}')]
    public function show(
        #[MapEntity(mapping: ['slug' => 'slug'])]
        Product $product
    ): Response {
        // use the Product!
        // ...
    }
}

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#[Route('/product/{product_id}')]
public function show(
    #[MapEntity(expr: 'repository.find(product_id)')]
    Product $product
): Response {
}

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#[Route('/posts_by/{author_id}')]
public function authorPosts(
    #[MapEntity(class: Post::class, expr: 'repository.findBy({"author": author_id}, {}, 10)')]
    iterable $posts
): Response {
}

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#[Route('/product/{id}/comments/{comment_id}')]
public function show(
    Product $product,
    #[MapEntity(expr: 'repository.find(comment_id)')]
    Comment $comment
): Response {
}

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#[Route('/product/{id}/comments')]
public function show(
    Product $product,
    #[MapEntity(expr: 'repository.findOneBy({"product": id}, {"createdAt": request.query.get("sort", "DESC")})')]
    Comment $comment
): Response {
}

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public function show(
    #[MapEntity]
    ProductInterface $product
): Response {
    // ...
}

Updating an Object

Once you've fetched an object from Doctrine, you interact with it the same as with any PHP model:

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// src/Controller/ProductController.php
namespace App\Controller;

use App\Entity\Product;
use App\Repository\ProductRepository;
use Doctrine\ORM\EntityManagerInterface;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;
// ...

class ProductController extends AbstractController
{
    #[Route('/product/edit/{id}', name: 'product_edit')]
    public function update(EntityManagerInterface $entityManager, int $id): Response
    {
        $product = $entityManager->getRepository(Product::class)->find($id);

        if (!$product) {
            throw $this->createNotFoundException(
                'No product found for id '.$id
            );
        }

        $product->setName('New product name!');
        $entityManager->flush();

        return $this->redirectToRoute('product_show', [
            'id' => $product->getId()
        ]);
    }
}

Using Doctrine to edit an existing product consists of three steps:

1. fetching the object from Doctrine;
2. modifying the object;
3. calling flush() on the entity manager.

You can call $entityManager->persist($product), but it isn't necessary: Doctrine is already "watching" your object for changes.

Deleting an Object

Deleting an object is very similar, but requires a call to the remove() method of the entity manager:

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

As you might expect, the remove() method notifies Doctrine that you'd like to remove the given object from the database. The DELETE query isn't actually executed until the flush() method is called.

Querying for Objects: The Repository

You've already seen how the repository object allows you to run basic queries without any work:

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// from inside a controller
$repository = $entityManager->getRepository(Product::class);
$product = $repository->find($id);

But what if you need a more complex query? When you generated your entity with make:entity, the command also generated a ProductRepository class:

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// src/Repository/ProductRepository.php
namespace App\Repository;

use App\Entity\Product;
use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository;
use Doctrine\Persistence\ManagerRegistry;

class ProductRepository extends ServiceEntityRepository
{
    public function __construct(ManagerRegistry $registry)
    {
        parent::__construct($registry, Product::class);
    }
}

When you fetch your repository (i.e. ->getRepository(Product::class)), it is actually an instance of this object! This is because of the repositoryClass config that was generated at the top of your Product entity class.

Suppose you want to query for all Product objects greater than a certain price. Add a new method for this to your repository:

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// src/Repository/ProductRepository.php

// ...
class ProductRepository extends ServiceEntityRepository
{
    public function __construct(ManagerRegistry $registry)
    {
        parent::__construct($registry, Product::class);
    }

    /**
     * @return Product[]
     */
    public function findAllGreaterThanPrice(int $price): array
    {
        $entityManager = $this->getEntityManager();

        $query = $entityManager->createQuery(
            'SELECT p
            FROM App\Entity\Product p
            WHERE p.price > :price
            ORDER BY p.price ASC'
        )->setParameter('price', $price);

        // returns an array of Product objects
        return $query->getResult();
    }
}

The string passed to createQuery() might look like SQL, but it is Doctrine Query Language. This allows you to type queries using commonly known query language, but referencing PHP objects instead (i.e. in the FROM statement).

Now, you can call this method on the repository:

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// from inside a controller
$minPrice = 1000;

$products = $entityManager->getRepository(Product::class)->findAllGreaterThanPrice($minPrice);

// ...

See Service Container for how to inject the repository into any service.

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// src/Repository/ProductRepository.php

// ...
class ProductRepository extends ServiceEntityRepository
{
    public function findAllGreaterThanPrice(int $price, bool $includeUnavailableProducts = false): array
    {
        // automatically knows to select Products
        // the "p" is an alias you'll use in the rest of the query
        $qb = $this->createQueryBuilder('p')
            ->where('p.price > :price')
            ->setParameter('price', $price)
            ->orderBy('p.price', 'ASC');

        if (!$includeUnavailableProducts) {
            $qb->andWhere('p.available = TRUE');
        }

        $query = $qb->getQuery();

        return $query->execute();

        // to get just one result:
        // $product = $query->setMaxResults(1)->getOneOrNullResult();
    }
}

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// src/Repository/ProductRepository.php

// ...
class ProductRepository extends ServiceEntityRepository
{
    public function findAllGreaterThanPrice(int $price): array
    {
        $conn = $this->getEntityManager()->getConnection();

        $sql = '
            SELECT * FROM product p
            WHERE p.price > :price
            ORDER BY p.price ASC
            ';

        $resultSet = $conn->executeQuery($sql, ['price' => $price]);

        // returns an array of arrays (i.e. a raw data set)
        return $resultSet->fetchAllAssociative();
    }
}

Configuration

See the Doctrine config reference.

Relationships and Associations

Doctrine provides all the functionality you need to manage database relationships (also known as associations), including ManyToOne, OneToMany, OneToOne and ManyToMany relationships.

For info, see How to Work with Doctrine Associations / Relations.

Database Testing

Read the article about testing code that interacts with the database.

Doctrine Extensions (Timestampable, Translatable, etc.)

Doctrine community has created some extensions to implement common needs such as "set the value of the createdAt property automatically when creating an entity". Read more about the available Doctrine extensions and use the StofDoctrineExtensionsBundle to integrate them in your application.

Learn more