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pair: Doctrine; MongoDB ODM

How to use MongoDB

The MongoDB Object Document Mapper (ODM) is much like the Doctrine2 ORM in its philosophy and how it works. In other words, like the Doctrine2 ORM</book/doctrine>, with the Doctrine ODM, you deal only with plain PHP objects, which are then persisted transparently to and from MongoDB.

Tip

You can read more about the Doctrine MongoDB ODM via the project's documentation.

A bundle is available that integrates the Doctrine MongoDB ODM into Symfony, making it easy to configure and use.

Note

This chapter will feel a lot like the Doctrine2 ORM chapter</book/doctrine>, which talks about how the Doctrine ORM can be used to persist data to relational databases (e.g. MySQL). This is on purpose - whether you persist to a relational database via the ORM or MongoDB via the ODM, the philosophies are very much the same.

Installation

To use the MongoDB ODM, you'll need two libraries provided by Doctrine and one bundle that integrates them into Symfony. If you're using the Symfony Standard Distribution, add the following to the deps file at the root of your project:

[doctrine-mongodb]
    git=http://github.com/doctrine/mongodb.git

[doctrine-mongodb-odm]
    git=http://github.com/doctrine/mongodb-odm.git

[DoctrineMongoDBBundle]
    git=http://github.com/symfony/DoctrineMongoDBBundle.git
    target=/bundles/Symfony/Bundle/DoctrineMongoDBBundle

Now, update the vendor libraries by running:

$ php bin/vendors install

Next, add the Doctrine\ODM\MongoDB and Doctrine\MongoDB namespaces to the app/autoload.php file so that these libraries can be autoloaded. Be sure to add them anywhere above the Doctrine namespace (shown here):

// app/autoload.php
$loader->registerNamespaces(array(
    // ...
    'Doctrine\\ODM\\MongoDB'    => __DIR__.'/../vendor/doctrine-mongodb-odm/lib',
    'Doctrine\\MongoDB'         => __DIR__.'/../vendor/doctrine-mongodb/lib',
    'Doctrine'                  => __DIR__.'/../vendor/doctrine/lib',
    // ...
));

Finally, enable the new bundle in the kernel:

// app/AppKernel.php
public function registerBundles()
{
    $bundles = array(
        // ...
        new Symfony\Bundle\DoctrineMongoDBBundle\DoctrineMongoDBBundle(),
    );

    // ...
}

Congratulations! You're ready to get to work.

Configuration

To get started, you'll need some basic configuration that sets up the document manager. The easiest way is to enable auto_mapping, which will activate the MongoDB ODM across your application:

# app/config/config.yml
doctrine_mongodb:
    connections:
        default:
            server: mongodb://localhost:27017
            options:
                connect: true
    default_database: test_database
    document_managers:
        default:
            auto_mapping: true

Note

Of course, you'll also need to make sure that the MongoDB server is running in the background. For more details, see the MongoDB Quick Start guide.

A Simple Example: A Product

The best way to understand the Doctrine MongoDB ODM is to see it in action. In this section, you'll walk through each step needed to start persisting documents to and from MongoDB.

Code along with the example

If you want to follow along with the example in this chapter, create an AcmeStoreBundle via:

php app/console generate:bundle --namespace=Acme/StoreBundle

Creating a Document Class

Suppose you're building an application where products need to be displayed. Without even thinking about Doctrine or MongoDB, you already know that you need a Product object to represent those products. Create this class inside the Document directory of your AcmeStoreBundle:

// src/Acme/StoreBundle/Document/Product.php
namespace Acme\StoreBundle\Document;

class Product
{
    protected $name;

    protected $price;
}

The class - often called a "document", meaning a basic class that holds data -is simple and helps fulfill the business requirement of needing products in your application. This class can't be persisted to Doctrine MongoDB yet -it's just a simple PHP class.

Add Mapping Information

Doctrine allows you to work with MongoDB in a much more interesting way than just fetching data back and forth as an array. Instead, Doctrine allows you to persist entire objects to MongoDB and fetch entire objects out of MongoDB. This works by mapping a PHP class and its properties to entries of a MongoDB collection.

For Doctrine to be able to do this, you just have to create "metadata", or configuration that tells Doctrine exactly how the Product class and its properties should be mapped to MongoDB. This metadata can be specified in a number of different formats including YAML, XML or directly inside the Product class via annotations:

// src/Acme/StoreBundle/Document/Product.php
namespace Acme\StoreBundle\Document;

use Doctrine\ODM\MongoDB\Mapping\Annotations as MongoDB;

/**
 * @MongoDB\Document
 */
class Product
{
    /**
     * @MongoDB\Id
     */
    protected $id;

    /**
     * @MongoDB\String
     */
    protected $name;

    /**
     * @MongoDB\Float
     */
    protected $price;
}
# src/Acme/StoreBundle/Resources/config/doctrine/Product.mongodb.yml
Acme\StoreBundle\Document\Product:
    fields:
        id:
            id:  true
        name:
            type: string
        price:
            type: float
<!-- src/Acme/StoreBundle/Resources/config/doctrine/Product.mongodb.xml -->
<doctrine-mongo-mapping xmlns="http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping
                    http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping.xsd">

    <document name="Acme\StoreBundle\Document\Product">
        <field fieldName="id" id="true" />
        <field fieldName="name" type="string" />
        <field fieldName="price" type="float" />
    </document>
</doctrine-mongo-mapping>

Doctrine allows you to choose from a wide variety of different field types, each with their own options. For information on the available field types, see the cookbook-mongodb-field-types section.

You can also check out Doctrine's Basic Mapping Documentation for all details about mapping information. If you use annotations, you'll need to prepend all annotations with MongoDB\ (e.g. MongoDB\String), which is not shown in Doctrine's documentation. You'll also need to include the use Doctrine\ODM\MongoDB\Mapping\Annotations as MongoDB; statement, which imports the MongoDB annotations prefix.

Generating Getters and Setters

Even though Doctrine now knows how to persist a Product object to MongoDB the class itself isn't really useful yet. Since Product is just a regular PHP class, you need to create getter and setter methods (e.g. getName(), setName()) in order to access its properties (since the properties are protected). Fortunately, Doctrine can do this for you by running:

php app/console doctrine:mongodb:generate:documents AcmeStoreBundle

This command makes sure that all of the getters and setters are generated for the Product class. This is a safe command - you can run it over and over again: it only generates getters and setters that don't exist (i.e. it doesn't replace your existing methods).

Note

Doctrine doesn't care whether your properties are protected or private, or whether or not you have a getter or setter function for a property. The getters and setters are generated here only because you'll need them to interact with your PHP object.

Persisting Objects to MongoDB

Now that you have a mapped Product document complete with getter and setter methods, you're ready to persist data to MongoDB. From inside a controller, this is pretty easy. Add the following method to the DefaultController of the bundle:

// src/Acme/StoreBundle/Controller/DefaultController.php
use Acme\StoreBundle\Document\Product;
use Symfony\Component\HttpFoundation\Response;
// ...

public function createAction()
{
    $product = new Product();
    $product->setName('A Foo Bar');
    $product->setPrice('19.99');

    $dm = $this->get('doctrine.odm.mongodb.document_manager');
    $dm->persist($product);
    $dm->flush();

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

Note

If you're following along with this example, you'll need to create a route that points to this action to see it in work.

Let's walk through this example:

  • lines 8-10 In this section, you instantiate and work with the $product object like any other, normal PHP object;
  • line 12 This line fetches Doctrine's document manager object, which is responsible for handling the process of persisting and fetching objects to and from MongoDB;
  • line 13 The persist() method tells Doctrine to "manage" the $product object. This does not actually cause a query to be made to MongoDB (yet).
  • line 14 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 MongoDB. In this example, the $product object has not been persisted yet, so the document manager makes a query to MongoDB, which adds a new entry.

Note

In fact, since Doctrine is aware of all your managed objects, when you call the flush() method, it calculates an overall changeset and executes the most efficient operation possible.

When creating or updating objects, the workflow is always the same. In the next section, you'll see how Doctrine is smart enough to update entries if they already exist in MongoDB.

Tip

Doctrine provides a library that allows you to programmatically load testing data into your project (i.e. "fixture data"). For information, see /cookbook/doctrine/doctrine_fixtures.

Fetching Objects from MongoDB

Fetching an object back out of MongoDB is even easier. For example, suppose you've configured a route to display a specific Product based on its id value:

public function showAction($id)
{
    $product = $this->get('doctrine.odm.mongodb.document_manager')
        ->getRepository('AcmeStoreBundle:Product')
        ->find($id);

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

    // do something, like pass the $product object into a template
}

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 objects of a certain class. You can access the repository object for a document class via:

$repository = $this->get('doctrine.odm.mongodb.document_manager')
    ->getRepository('AcmeStoreBundle:Product');

Note

The AcmeStoreBundle:Product string is a shortcut you can use anywhere in Doctrine instead of the full class name of the document (i.e. Acme\StoreBundle\Document\Product). As long as your document lives under the Document namespace of your bundle, this will work.

Once you have your repository, you have access to all sorts of helpful methods:

// query by the primary key (usually "id")
$product = $repository->find($id);

// dynamic method names to find based on a column value
$product = $repository->findOneById($id);
$product = $repository->findOneByName('foo');

// find *all* products
$products = $repository->findAll();

// find a group of products based on an abitrary column value
$products = $repository->findByPrice(19.99);

Note

Of course, you can also issue complex queries, which you'll learn more about in the book-doctrine-queries section.

You can also take advantage of the useful findBy and findOneBy methods to easily fetch objects based on multiple conditions:

// query for one product matching be name and price
$product = $repository->findOneBy(array('name' => 'foo', 'price' => 19.99));

// query for all prdocuts matching the name, ordered by price
$product = $repository->findBy(
    array('name' => 'foo'),
    array('price', 'ASC')
);

Updating an Object

Once you've fetched an object from Doctrine, updating it is easy. Suppose you have a route that maps a product id to an update action in a controller:

public function updateAction($id)
{
    $dm = $this->get('doctrine.odm.mongodb.document_manager');
    $product = $dm->getRepository('AcmeStoreBundle:Product')->find($id);

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

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

    return $this->redirect($this->generateUrl('homepage'));
}

Updating an object involves just three steps:

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

Notice that calling $dm->persist($product) isn't necessary. Recall that this method simply tells Doctrine to manage or "watch" the $product object. In this case, since you fetched the $product object from Doctrine, it's already managed.

Deleting an Object

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

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

As you might expect, the remove() method notifies Doctrine that you'd like to remove the given document from the MongoDB. The actual delete operation however, isn't actually executed until the flush() method is called.

Querying for Objects

As you saw above, the built-in repository class allows you to query for one or many objects based on an number of different parameters. When this is enough, this is the easiest way to query for documents. Of course, you can also create more complex queries.

Using the Query Builder

Doctrine's ODM ships with a query "Builder" object, which allows you to construct a query for exactly which documents you want to return. If you use an IDE, you can also take advantage of auto-completion as you type the method names. From inside a controller:

$products = $this->get('doctrine.odm.mongodb.document_manager')
    ->createQueryBuilder('AcmeStoreBundle:Product')
    ->field('name')->equals('foo')
    ->limit(10)
    ->sort('price', 'ASC')
    ->getQuery()
    ->execute()

In this case, 10 products with a name of "foo", ordered from lowest price to highest price are returned.

The QueryBuilder object contains every method necessary to build your query. For more information on Doctrine's Query Builder, consult Doctrine's Query Builder documentation. For a list of the available conditions you can place on the query, see the Conditional Operators documentation specifically.

Custom Repository Classes

In the previous section, you began constructing and using more complex queries from inside a controller. In order to isolate, test and reuse these queries, it's a good idea to create a custom repository class for your document and add methods with your query logic there.

To do this, add the name of the repository class to your mapping definition.

// src/Acme/StoreBundle/Document/Product.php
namespace Acme\StoreBundle\Document;

use Doctrine\ODM\MongoDB\Mapping\Annotations as MongoDB;

/**
 * @MongoDB\Document(repositoryClass="Acme\StoreBundle\Repository\ProductRepository")
 */
class Product
{
    //...
}
# src/Acme/StoreBundle/Resources/config/doctrine/Product.mongodb.yml
Acme\StoreBundle\Document\Product:
    repositoryClass: Acme\StoreBundle\Repository\ProductRepository
    # ...
<!-- src/Acme/StoreBundle/Resources/config/doctrine/Product.mongodb.xml -->
<!-- ... -->
<doctrine-mongo-mapping xmlns="http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping
                    http://doctrine-project.org/schemas/odm/doctrine-mongo-mapping.xsd">

    <document name="Acme\StoreBundle\Document\Product"
            repository-class="Acme\StoreBundle\Repository\ProductRepository">
        <!-- ... -->
    </document>

</doctrine-mong-mapping>

Doctrine can generate the repository class for you by running the same command used earlier to generate the missing getter and setter methods:

php app/console doctrine:mongodb:generate:documents AcmeStoreBundle

Next, add a new method - findAllOrderedByName() - to the newly generated repository class. This method will query for all of the Product documents, ordered alphabetically.

// src/Acme/StoreBundle/Repository/ProductRepository.php
namespace Acme\StoreBundle\Repository;

use Doctrine\ODM\MongoDB\DocumentRepository;

class ProductRepository extends DocumentRepository
{
    public function findAllOrderedByName()
    {
        return $this->createQueryBuilder()
            ->sort('name', 'ASC')
            ->getQuery()
            ->execute();
    }
}

You can use this new method just like the default finder methods of the repository:

$product = $this->get('doctrine.odm.mongodb.document_manager')
    ->getRepository('AcmeStoreBundle:Product')
    ->findAllOrderedByName();

Note

When using a custom repository class, you still have access to the default finder methods such as find() and findAll().

Doctrine Extensions: Timestampable, Sluggable, etc.

Doctrine is quite flexible, and a number of third-party extensions are available that allow you to easily perform repeated and common tasks on your entities. These include thing such as Sluggable, Timestampable, Loggable, Translatable, and Tree.

For more information on how to find and use these extensions, see the cookbook article about using common Doctrine extensions</cookbook/doctrine/common_extensions>.

Doctrine Field Types Reference

Doctrine comes with a large number of field types available. Each of these maps a PHP data type to a specific MongoDB type. The following are just some of the types supported by Doctrine:

  • string
  • int
  • float
  • date
  • timestamp
  • boolean
  • file

For more information, see Doctrine's Mapping Types documentation.

single: Doctrine; ODM Console Commands single: CLI; Doctrine ODM

Console Commands

The Doctrine2 ODM integration offers several console commands under the doctrine:mongodb namespace. To view the command list you can run the console without any arguments:

php app/console

A list of available command will print out, many of which start with the doctrine:mongodb prefix. You can find out more information about any of these commands (or any Symfony command) by running the help command. For example, to get details about the doctrine:mongodb:query task, run:

php app/console help doctrine:mongodb:query

Note

To be able to load data fixtures into MongoDB, you will need to have the DoctrineFixturesBundle bundle installed. To learn how to do it, read the "/cookbook/doctrine/doctrine_fixtures" entry of the Cookbook.

single: Configuration; Doctrine MongoDB ODM single: Doctrine; MongoDB ODM configuration

Configuration

For detailed information on configuration options available when using the Doctrine ODM, see the MongoDB Reference</reference/configuration/mongodb> section.

Registering Event Listeners and Subscribers

Doctrine allows you to register listeners and subscribers that are notified when different events occur inside Doctrine's ODM. For more information, see Doctrine's Event Documentation.

In Symfony, you can register a listener or subscriber by creating a service and then tagging<book-service-container-tags> it with a specific tag.

  • event listener: Use the doctrine.odm.mongodb.<connection>_event_listener tag, where <connection> name is replaced by the name of your connection (usually default). Also, be sure to add an event key to the tag specifying which event to listen to. Assuming your connection is called default, then:

    services:
    my_doctrine_listener:
        class:   Acme\HelloBundle\Listener\MyDoctrineListener
        # ...
        tags:
            -  { name: doctrine.odm.mongodb.default_event_listener, event: postPersist }
    <service id="my_doctrine_listener" class="Acme\HelloBundle\Listener\MyDoctrineListener">
    <!-- ... -->
    <tag name="doctrine.odm.mongodb.default_event_listener" event="postPersist" />
</service>.
    $definition = new Definition('Acme\HelloBundle\Listener\MyDoctrineListener');
// ...
$definition->addTag('doctrine.odm.mongodb.default_event_listener');
$container->setDefinition('my_doctrine_listener', $definition);
  • event subscriber: Use the doctrine.odm.mongodb.<connection>_event_subscriber tag. No other keys are needed in the tag.

Summary

With Doctrine, you can focus on your objects and how they're useful in your application and worry about persisting to MongoDB second. This is because Doctrine allows you to use any PHP object to hold your data and relies on mapping metadata information to map an object's data to a MongoDB collection.

And even though Doctrine revolves around a simple concept, it's incredibly powerful, allowing you to create complex queries and subscribe to events that allow you to take different actions as objects go through their persistence lifecycle.