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Databases and the Doctrine ORM

4.0 version

Databases and the Doctrine ORM

Symfony doesn't provide a component to work with the database, but it does provide tight integration with a third-party library called Doctrine.

Note

This article is all about using the Doctrine ORM. If you prefer to use raw database queries, see the "How to Use Doctrine DBAL" article instead.

You can also persist data to MongoDB using Doctrine ODM library. See the "DoctrineMongoDBBundle" documentation.

Installing Doctrine

First, install Doctrine, as well as the MakerBundle, which will help generate some code:

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composer require doctrine
composer require maker --dev

Configuring the Database

The database connection information is stored as an environment variable called DATABASE_URL. For development, you can find and customize this inside .env:

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# .env

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

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

Caution

If the username, password or database name contain any character considered special in a URI (such as !, @, $, #), you must encode them. See RFC 3986 for the full list of reserved characters or use the urlencode function to encode them.

Now that your connection parameters are setup, Doctrine can create the db_name database for you:

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$ php bin/console doctrine:database:create

There are more options in config/packages/doctrine.yaml that you can configure, including your server_version (e.g. 5.7 if you're using MySQL 5.7), which may affect how Doctrine functions.

Tip

There are many other Doctrine commands. Run php bin/console list doctrine to see a full list.

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)

New in version The: interactive behavior of the make:entity command was introduced in MakerBundle 1.3.

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

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

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass="App\Repository\ProductRepository")
 */
class Product
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $name;

    /**
     * @ORM\Column(type="integer")
     */
    private $price;

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

    // ... getter and setter methods
}

Note

Confused why the price is an integer? Don't worry: this is just an example. But, storing prices as integers (e.g. 100 = $1 USD) can avoid rounding issues.

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 annotations: the @ORM\... comments that you see above each property:

_images/mapping_single_entity.png

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. To see a full list, check out Doctrine's Mapping Types documentation. If you want to use XML instead of annotations, add type: xml and dir: '%kernel.project_dir%/config/doctrine' to the entity mappings in your config/packages/doctrine.yaml file.

Caution

Be careful not to use reserved SQL keywords as your table or column names (e.g. GROUP or USER). See Doctrine's Reserved SQL keywords documentation for details on how to escape these. Or, change the table name with @ORM\Table(name="groups") above the class or configure the column name with the name="group_name" option.

Migrations: Creating the Database Tables/Schema

The Product class is fully-configured and ready to save to a product table. Of course, 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:

SUCCESS!

Next: Review the new migration "src/Migrations/Version20180207231217.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? It's easy to add the new property by hand. 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
// ...

class Product
{
    // ...

+     /**
+      * @ORM\Column(type="text")
+      */
+     private $description;

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

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

Tip

If you prefer to add new properties manually, the make:entity command can generate the getter & setter methods for you:

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$ php bin/console make:entity --regenerate

If you make some changes and want to regenerate all getter/setter methods, also pass --overwrite.

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;

class ProductController extends Controller
{
    /**
     * @Route("/product", name="product")
     */
    public function index()
    {
        // you can fetch the EntityManager via $this->getDoctrine()
        // or you can add an argument to your action: index(EntityManagerInterface $entityManager)
        $entityManager = $this->getDoctrine()->getManager();

        $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!

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 doctrine:query:sql 'SELECT * FROM product'

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

Take a look at the previous example in more detail:

  • line 16 The $this->getDoctrine()->getManager() method gets Doctrine's entity manager object, which is the most important object in Doctrine. It's responsible for saving objects to, and fetching objects from, the database.
  • lines 18-21 In this section, you instantiate and work with the $product object like any other normal PHP object.
  • line 24 The persist($product) call tells Doctrine to "manage" the $product object. This does not cause a query to be made to the database.
  • line 27 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.

Note

If the flush() call fails, a Doctrine\ORM\ORMException exception is thrown. See Transactions and Concurrency.

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

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
// ...

/**
 * @Route("/product/{id}", name="product_show")
 */
public function showAction($id)
{
    $product = $this->getDoctrine()
        ->getRepository(Product::class)
        ->find($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]);
}

Try it out!

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 = $this->getDoctrine()->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 Querying for Objects: The Repository 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:

_images/doctrine_web_debug_toolbar.png

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, try running composer require profiler to install it.

Automatically Fetching Objects (ParamConverter)

In many cases, you can use the SensioFrameworkExtraBundle to do the query for you automatically! First, install the bundle in case you don't have it:

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$ composer require annotations

Now, simplify your controller:

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// src/Controller/ProductController.php

use App\Entity\Product;
// ...

/**
 * @Route("/product/{id}", name="product_show")
 */
public function showAction(Product $product)
{
    // use the Product!
    // ...
}

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

There are many more options you can use. Read more about the ParamConverter.

Updating an Object

Once you've fetched an object from Doctrine, updating it is easy:

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/**
 * @Route("/product/edit/{id}")
 */
public function updateAction($id)
{
    $entityManager = $this->getDoctrine()->getManager();
    $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()
    ]);
}

Updating an object involves just 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:

$entityManager->remove($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:

// from inside a controller
$repository = $this->getDoctrine()->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 Symfony\Bridge\Doctrine\RegistryInterface;

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

    /**
     * @param $price
     * @return Product[]
     */
    public function findAllGreaterThanPrice($price): array
    {
        // automatically knows to select Products
        // the "p" is an alias you'll use in the rest of the query
        $qb = $this->createQueryBuilder('p')
            ->andWhere('p.price > :price')
            ->setParameter('price', $price)
            ->orderBy('p.price', 'ASC')
            ->getQuery();

        return $qb->execute();

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

This uses Doctrine's Query Builder: a very powerful and user-friendly way to write custom queries. Now, you can call this method on the repository:

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// from inside a controller
$minPrice = 1000;

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

// ...

If you're in a Injecting Services/Config into a Service, you can type-hint the ProductRepository class and inject it like normal.

For more details, see the Query Builder Documentation from Doctrine.

Querying with DQL or SQL

In addition to the query builder, you can also query with Doctrine Query Language:

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// src/Repository/ProductRepository.php
// ...

public function findAllGreaterThanPrice($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', 1000);

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

Or directly with SQL if you need to:

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// src/Repository/ProductRepository.php
// ...

public function findAllGreaterThanPrice($price): array
{
    $conn = $this->getEntityManager()->getConnection();

    $sql = '
        SELECT * FROM product p
        WHERE p.price > :price
        ORDER BY p.price ASC
        ';
    $stmt = $conn->prepare($sql);
    $stmt->execute(['price' => 1000]);

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

With SQL, you will get back raw data, not objects (unless you use the NativeQuery functionality).

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.

Dummy Data Fixtures

Doctrine provides a library that allows you to programmatically load testing data into your project (i.e. "fixture data"). For information, see the "DoctrineFixturesBundle" documentation.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.