Doctrine arraycollection keeps being null - php

Question

Hey Im just trying out doctrine for php alittle and i got an issue with my $matches arraycollection, when i set it in the __construct it works but afterwards its just null and i cant seem to figure out why, the other arraycollections works perfectly
<?php
// src/Player.php
use Doctrine\Common\Collections\ArrayCollection;
/**
* #Entity #Table(name="teams")
**/
class Team
{
/**
* #Id #Column(type="integer") #GeneratedValue
**/
protected $id;
/**
* #Column(type="string")
**/
protected $name;
/**
* #OneToMany(targetEntity="Player", mappedBy="team")
**/
protected $players;
/**
* #OneToMany(targetEntity="Goal",mappedBy="againstTeam")
**/
protected $goalsAgainst;
/**
* #Column(type="string")
**/
protected $color;
/**
* ManyToMany(targetEntity="Match", mappedBy="teams")
**/
protected $matches;
public function __construct()
{
$this->matches = new ArrayCollection();
$this->players = new ArrayCollection();
$this->goalsAgainst = new ArrayCollection();
}
public function getId() {
return $this->id;
}
public function getName() {
return $this->name;
}
public function getMatches() {
return $this->matches;
}
public function addMatch(Match $match) {
$this->matches->add($match);
}
public function setName($name) {
$this->name = $name;
}
public function setColor($color) {
$this->color = $color;
}
public function addGoalsAgainst(Goal $goal) {
$this->goalsAgainst->add($goal);
$goal->setAgainstTeam($this);
}
public function getJson() {
return array(
'Id'=>$this->id,
'Name'=>$this->name,
'Players'=>null,
'GoalsAgainst'=>null,
'Color'=>$this->color,
'Matches'=>null
);
}
}
?>
if i add an nullcheck to the addMatches(Match $match) like
public function addMatch(Match $match) {
if ($this->matches == null) {
$this->matches = new ArrayCollection();
}
$this->matches->add($match);
}
then the match is added but if i then at next line uses $team->getMatches() then the $matches is null again