One-To-Many relationship deletes foreign key in Doctrine - php

Question

This is driving me crazy.
A Client can have many Vehicles.
This is a one to many relationship. When trying to save the entities I get an error saying that the foreign key is null. When I remove the Doctrine relation and store the Vehicle separately everything is working fine.
This is how I created the relation:
class Vehicle {
...
/**
* #ORM\ManyToOne(targetEntity="Client", inversedBy="vehicles")
* #ORM\JoinColumn(name="client_id", referencedColumnName="id")
*/
public $client;
}
class Client {
...
public function __construct()
{
parent::__construct();
$this->vehicles = new \Doctrine\Common\Collections\ArrayCollection();
}
/**
* #ORM\OneToMany(targetEntity="Vehicle", mappedBy="client", cascade={"persist"})
*/
private $vehicles;
}
I try to save the entities like this:
$client = new Client();
$vehicle = new Vehicle();
$client->getVehicles()->add($vehicle);
$em->persist($client);
$em->flush();
Next I get a PDO exception saying that client_id can't be null on the Vehicle table.
It seems like Doctrine is not copying the foreign key correctly.
What am I doing wrong?

Answer 1

According to their docs:
It is not possible to use join columns pointing to non-primary keys.
Doctrine will think these are the primary keys and create lazy-loading proxies with the data, which can lead to unexpected results. Doctrine can for performance reasons not validate the correctness of this settings at runtime but only through the Validate Schema command.
Obviously you need a different approach.
A solution is given in their example:
CREATE TABLE product (
id INTEGER,
name VARCHAR,
PRIMARY KEY(id)
);
CREATE TABLE product_attributes (
product_id INTEGER,
attribute_name VARCHAR,
attribute_value VARCHAR,
PRIMARY KEY (product_id, attribute_name)
);
This schema should be mapped to a Product Entity as follows:
class Product
{
private $id;
private $name;
private $attributes = array();
}
Where the attribute_name column contains the key and attribute_value contains the value of each array element in $attributes.