How to merge two php Doctrine 2 ArrayCollection()

Better (and working) variant for me:

$collection3 = new ArrayCollection(    array_merge($collection1->toArray(), $collection2->toArray()));

You can simply do:

$a = new ArrayCollection();$b = new ArrayCollection();...$c = new ArrayCollection(array_merge((array) $a, (array) $b));

If you are required to prevent any duplicates, this snippet might help. It uses a variadic function parameter for usage with PHP5.6.

/** * @param array... $arrayCollections * @return ArrayCollection */public function merge(...$arrayCollections){    $returnCollection = new ArrayCollection();    /**     * @var ArrayCollection $arrayCollection     */    foreach ($arrayCollections as $arrayCollection) {        if ($returnCollection->count() === 0) {            $returnCollection = $arrayCollection;        } else {            $arrayCollection->map(function ($element) use (&$returnCollection) {                if (!$returnCollection->contains($element)) {                    $returnCollection->add($element);                }            });        }    }    return $returnCollection;}

Might be handy in some cases.