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Symfony2 – Franz Jordán 2011
Databases and Doctrine ("The
Model")
Let's face it, one of the most common and challenging tasks for any application involves
persisting and reading information to and from a database. Fortunately, Symfony comes
integrated withDoctrine, a library whose sole goal is to give you powerful tools to make this
easy. In this chapter, you'll learn the basic philosophy behind Doctrine and see how easy working
with a database can be.
Doctrine is totally decoupled from Symfony and using it is optional. This chapter is all about the
Doctrine ORM, which aims to let you map objects to a relational database (such
as MySQL, PostgreSQL or Microsoft SQL). If you prefer to use raw database queries, this is easy,
and explained in the "How to use Doctrine's DBAL Layer" cookbook entry.
You can also persist data to MongoDB using Doctrine ODM library. For more information, read
the "DoctrineMongoDBBundle" documentation.
A Simple Example: A Product
The easiest way to understand how Doctrine works is to see it in action. In this section, you'll
configure your database, create a Product object, persist it to the database and fetch it back
out.
Code along with the example
If you want to follow along with the example in this chapter, create anAcmeStoreBundle via:
php app/console generate:bundle --namespace=Acme/StoreBundle
Configuring the Database
Before you really begin, you'll need to configure your database connection information. By
convention, this information is usually configured in an app/config/parameters.ini file:
;app/config/parameters.ini
[parameters]
database_driver = pdo_mysql
database_host = localhost
database_name = test_project
database_user = root
database_password = password
Defining the configuration via parameters.ini is just a convention. The parameters defined in
that file are referenced by the main configuration file when setting up Doctrine:
doctrine:
dbal:
driver: %database_driver%
host: %database_host%
dbname: %database_name%
user: %database_user%
password: %database_password%
By separating the database information into a separate file, you can easily keep different version
of the file on each server. You can also easily store database configuration (or any sensitive
information) outside of your project, like inside your Apache configuration, for example. For
more information, see How to Set External Parameters in the Service Container.
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