Best way for extending a entity in doctrine - symfony

Question

I have a User Entity in a small Framework made by me. Now i want to use this User Entity in several projects.
But in some projects I want to add a few fields to the User Entity without modifying the file.
What I tried so far:
I created a new DefaultUser Entity in a DefaultUser Bundle and made the User Entity a mappedsuperclass. But now I can't make a association in other entities like
/*
* #ORM\ManyToOne(targetEntity="User", inversedBy="jobs")
* #ORM\JoinColumn(name="user", referencedColumnName="id")
*/
private $user;
Because Doctrine can't find the id column in the user entity. This only works if I specify the DefaultUser Entity. According to the doctrine documentation this only works on many to many associations if only one leaf exists.
Then I tried Single Table Inheritance. This works fine but I have to modify the DiscriminatorMap if I want to extend my user entity which is shared acros multiple projects...
So whats the best way to extend the UserEntity?

Answer 1

I have precisely the same problem - I have just switched from RedBean to Doctrine (for a project using the Zend Framework), and the structure of my classes did not take into account this issue. The core problem is that maps in Doctrine have a one to one relationship with classes, as far as I can work out. What we are looking for is a way to have one concrete class (the UserEntity) that uses a map from an abstract class (the DefaultUser). My solution, which may be something of a hack (I've only been using Doctrine for a couple of days), works for YAML at least:
Create a new mapping driver extending the YAML driver, and override the _loadMappingFile method with something like this:
class MyLibrary_Doctrine_Mapping_Driver_YamlExtended extends MyLibrary_Doctrine_Mapping_Driver_YamlExtended
{
protected $_basicEntityFolder;
protected function _loadMappingFile($file)
{
$entMaps = parent::_loadMappingFile($file);
//merge this with any extensions if defined
foreach($entMaps as $ent => $map)
{ //load the relevant map
if (!isset($map['extendEntity'])) {
continue;
}
$fileName = $this->_basicEntityFolder . DIRECTORY_SEPARATOR . str_replace('\\', '.', $map['extendEntity']) . $this->_fileExtension;
$extendedMaps = $this->_loadMappingFile($fileName);
if (!is_array($extendedMaps[$map['extendEntity']])) {
throw new MyProject_Doctrine_Exception("Entity to extend from could not be found.");
}
//merge so that the file lower in the class hierachy always overrides the higher
$map = array_merge($extendedMaps[$map['extendEntity']], $map);
//clear the extendEntity value
unset($map['extendEntity']);
$entMaps[$ent] = $map;
}
return $entMaps;
}
public function setExtendedEntitiesFolder($path)
{
$this->_basicEntityFolder = $path;
}
}
I then have two yaml files, in different folders, like this:
#MyApplication/Entities/Maps/Entities.User.dcm.yml
Entities\User:
extendEntity: LibraryEntities\User
That is the file in the application. Then in the library I have
#Library/Entities/Maps/ExtendedEntities/LibraryEntities.User.dcm.yml
LibraryEntities\User:
type: entity
table: user
fields:
username:
type: text
nullable: true
password:
type: text
nullable: true
defaultProfile:
type: text
nullable: true
column: default_profile
The reason it is in an ExtendedEntities folder is so I can define mappedSuperclasses in the library using a normal namespace, and Doctrine will load those automatically when a class extends them, but these extendedentities are outside of the path for Doctrine's usual class inheritance loading (if they were all in the normal folder structure then for eg "class ApplicationUser extends LibraryUser" Doctrine would try to load the config for LibraryUser because it would find it, and then cause the same error you have already encountered).
Then when I set up my $em I provide it with my driver:
$driverImpl = new MyLibrary_Doctrine_Mapping_Driver_YamlExtended(array(APPLICATION_PATH . '/entities/maps',
LIBRARY_PATH . '/Entities/Maps'));
$driverImpl->setExtendedEntitiesFolder(LIBRARY_PATH . '/Entities/Maps/ExtendedEntities');
Notice that this solution allows inheritance chains defined by 'extendEntity' (because the _loadMappingFile method is recursive). Also that any configuration file lower down the chain can overwrite any property already defined, so even if in your library yaml you had:
username:
type: text
Say you had a project in which usernames where integers you can simply override it in your application config with
username:
type: int
or whatever.
And therefore this solves the problem of defining Doctrine style inheritance on the base class. In every project you can define the DiscriminatorMap however you like.
In principle the same solution could be applied to annotations, though extending the annotation driver is a little more complicated, because it doesn't simply read metadata by reading one file in one go and converting it to an array, but makes numerous requests to the annotation reader, which means implementing this structure would be trickier.
I'd be very interested to know how other people have solved this problem.