How can I have two User that share the same table? - symfony

Question

I have an entity User with lots of feature built for it.
/**
* #ORM\Entity(repositoryClass="App\Repository\UserRepository")
* #UniqueEntity("email", message="Email already in use")
* #ORM\HasLifecycleCallbacks
* #Table(name="users")
*/
class User implements UserInterface
{
/* variables + getter & setter */
}
This entity is good as is for most of my User.
However, a few of them will have a special ROLE, ROLE_TEACHER.
With this role, I need to store a lot of new variables specially for them.
If I create a new entity Teacher, doctrine creates a new table with every User's data + the Teacher's data.
/**
* #ORM\Entity(repositoryClass="App\Repository\TeacherRepository")
* #Table(name="teachers")
*/
class Teacher extends User
{
/**
* #ORM\Column(type="string", length=64, nullable=true)
*/
protected $test;
public function __construct()
{
parent::__construct();
}
}
What I want, is for Teacher & User to share the users table and have the teachers table only store the extra data. How could I achieve that ?

Answer 1

This is more of system design problem than implementation problem. as #Gary suggested you can make use of Inheritance Mapping which can have Performance issues, I'd rather suggest re think your schema and make use of database normalization techniques to break up your data into more manageable entities.
You can have User entity :
/**
* #ORM\Entity(repositoryClass="App\Repository\UserRepository")
* #UniqueEntity("email", message="Email already in use")
* #ORM\HasLifecycleCallbacks
* #Table(name="users")
*/
class User implements UserInterface
{
/* variables + getter & setter */
/**
* One user has many attibute data. This is the inverse side.
* #OneToMany(targetEntity="UserData", mappedBy="data")
*/
private $data;
}
With other UserData Entity with OneToMany relationship :
/**
* #ORM\Entity(repositoryClass="App\Repository\UserDataRepository")
* #Table(name="user_data")
*/
class UserData
{
/* variables + getter & setter */
#ORM\Id()
private $id;
/**
* Many features have one product. This is the owning side.
* #ManyToOne(targetEntity="User", inversedBy="data")
* #JoinColumn(name="user_id", referencedColumnName="id")
*/
private $user;
/**
* #ORM\Column(type="string")
*/
private $attribute;
/*
* #ORM\Column(name="value", type="object")
*/
private $value;
}
Now you can have list of user attributes without requiring specific structure to each role. It's scalable and arbitrary.
You can also define same Relation with TeacherData, StudentData or UserProfile Entities with foreign keys and branch your application logic according to the roles. Key is to break data into their separate domains and keep common data in one table. Load related data by querying related entity, this increases readability and makes it easy to break complex structure into manageable codebase.