Separating Concerns using Embeddables¶
Embeddables are classes which are not entities themselves, but are embedded in entities and can also be queried in DQL. You’ll mostly want to use them to reduce duplication or separating concerns. Value objects such as date range or address are the primary use case for this feature.
Note
Embeddables can only contain properties with basic @Column
mapping.
For the purposes of this tutorial, we will assume that you have a User
class in your application and you would like to store an address in
the User
class. We will model the Address
class as an embeddable
instead of simply adding the respective columns to the User
class.
In terms of your database schema, Doctrine will automatically inline all
columns from the Address
class into the table of the User
class,
just as if you had declared them directly there.
Initializing embeddables¶
In case all fields in the embeddable are nullable
, you might want
to initialize the embeddable, to avoid getting a null value instead of
the embedded object.
public function __construct()
{
$this->address = new Address();
}
Column Prefixing¶
By default, Doctrine names your columns by prefixing them, using the value object name.
Following the example above, your columns would be named as address_street
,
address_postalCode
…
You can change this behaviour to meet your needs by changing the
columnPrefix
attribute in the @Embedded
notation.
The following example shows you how to set your prefix to myPrefix_
:
To have Doctrine drop the prefix and use the value object’s property name
directly, set columnPrefix=false
(use-column-prefix="false"
for XML):
DQL¶
You can also use mapped fields of embedded classes in DQL queries, just
as if they were declared in the User
class:
SELECT u FROM User u WHERE u.address.city = :myCity