Doctrine nullable one-to-one relationship still wants to create unique index - php

Question

I have a Person entity which has two relations (hometown and current) to Location table. Both of these fields can be null, otherwise they must exist in the Location table:
class Person {
.....
/**
* #var Location
* #ORM\OneToOne(targetEntity="Location")
* #ORM\JoinColumn(name="hometown_id", referencedColumnName="id",nullable=true)
**/
protected $hometown;
/**
* #var Location
* #ORM\OneToOne(targetEntity="Location")
* #ORM\JoinColumn(name="current_id", referencedColumnName="id", nullable=true)
**/
protected $current;
....
}
Now, I want to update my db schema, based on doctrine:schema:update --dump-sql output, but it creates problems:
CREATE UNIQUE INDEX UNIQ_8D93D6494341EE7D ON person (hometown_id);
CREATE UNIQUE INDEX UNIQ_8D93D649B8998A57 ON person (current_id);
I cannot define these indexes as there are more than one null row in the table.
Would you please help me?

Answer 1

A OneToOne relationship is unique as it would mean that only one person could be assigned to one location and one location to one person.
In your scenario you would want one person to have multiple locations and one location could have multiple person(s). This would be a ManyToMany relationship.
In Doctrine when you use a ManyToMany you will specify a JoinTable that Doctrine will manage (You don't have to create an entity for a JoinTable). The JoinTable breaks down the ManyToMany to something like a OneToMany such as one person to many location(s) as shown in example below. The JoinTable will store the values you want when they apply.
/**
* #ORM\ManyToMany(targetEntity="Location")
* #ORM\JoinTable(name="hometown_location",
* joinColumns={#ORM\JoinColumn(name="person_id", referencedColumnName="id", unique=true)},
* inverseJoinColumns={#ORM\JoinColumn(name="location_id", referencedColumnName="id")}
* )
**/
protected $hometown;
/**
* #ORM\ManyToMany(targetEntity="Location")
* #ORM\JoinTable(name="current_location",
* joinColumns={#ORM\JoinColumn(name="person_id", referencedColumnName="id", unique=true)},
* inverseJoinColumns={#ORM\JoinColumn(name="location_id", referencedColumnName="id")}
* )
**/
protected $current;
public function __construct() {
$this->hometown = new \Doctrine\Common\Collections\ArrayCollection();
$this->hometown = new \Doctrine\Common\Collections\ArrayCollection();
}
If there is no location to assign to hometown or current that is fine, no space is taken up.
When you do have a location to assign to either hometown or current it will have to be a valid location from the location table.

Answer 2

It looks like you are looking for FOREIGN KEY
http://dev.mysql.com/doc/refman/5.6/en/create-table-foreign-keys.html
ALTER TABLE `Person` ADD INDEX ( `hometown_id` ) ;
ALTER TABLE `Person` ADD FOREIGN KEY ( `hometown_id` ) REFERENCES `Location` ( `id` )
ON DELETE RESTRICT ON UPDATE RESTRICT ;
ALTER TABLE `Person` ADD INDEX ( `current_id` ) ;
ALTER TABLE `Person` ADD FOREIGN KEY ( `current_id` ) REFERENCES `Location` ( `id` )
ON DELETE RESTRICT ON UPDATE RESTRICT ;