Symfony 3 - Multiple relationships to the same Data Model - symfony

Question

I have the following code in Symfony 3:
A class Appointment
<?php
/**
* Appointment
*
* #ORM\Entity
* #ORM\Table(name="ev_appointment")
*/
class Appointment
{
/**
* #ORM\OneToMany(targetEntity="EmailForward", mappedBy="_appointment")
*/
private $_email_forwards;
/**
* #ORM\OneToMany(targetEntity="ParticipationRequest", mappedBy="_appointment")
*/
private $_participation_requests;
}
A class EmailForward
<?php
/**
* #ORM\Entity
* #ORM\Table(name="ev_email_forward")
*/
class EmailForward
{
/**
* #ORM\ManyToOne(targetEntity="Appointment" , inversedBy="_email_forwards")
* #ORM\JoinColumn(name="ev_appointment_id", referencedColumnName="id")
*/
private $_appointment;
/**
* #ORM\Column(type="string", length=255, name="email", nullable=true)
*/
private $_email;
/**
* #ORM\Column(type="datetime", name="forwarded_at", nullable=true)
*/
private $_forwarded_at;
/**
* #ORM\Column(type="string", length=255, name="source", nullable=true)
*/
private $_source;
}
A class ParticipationRequest
<?php
/**
* #ORM\Entity
* #ORM\Table(name="ev_participation_request")
*/
class ParticipationRequest
{
/**
* #ORM\ManyToOne(targetEntity="Appointment", inversedBy="_participation_requests")
* #ORM\JoinColumn(name="ev_appointment_id", referencedColumnName="id")
*/
private $_appointment;
/**
* #ORM\Column(type="string", length=255, name="email", nullable=true)
*/
private $_email;
/**
* #ORM\Column(type="datetime", name="forwarded_at", nullable=true)
*/
private $_forwarded_at;
/**
* #ORM\Column(type="string", length=255, name="source", nullable=true)
*/
private $_source;
}
Now seems to me like I have 2 relationships with 2 Entities that have the exact same structure. So I am wondering, what is the right way to go?
On the one hand I could leave it as it is, because it does, work. But again, if some information was to be the same in both fields, it seems kinda like a waste to have 2 DB entries with the exact same info, and also harder to mantain afterwards.
Is there a more intelligent approach to solve this issue?

Answer 1

You could use e.g. Single Table Inheritance.
By that you only define the structure for EmailForward and ParticipationRequest once and all data will be persisted in one table in the database. During ORM mapping Doctrine will recognize which type you're using and instantiate the correct Object for you.
I don't see how to solve the 'if data is same in both relations it will be peristed twice' because
if it was always the same you wouldn't need two relations
there is no real way to keep it in one persistence - only option I see would be to create another relation from EmailForward and ParticipationRequest which keeps the data which might be needed twice and is referenced from both Objects then.