How to merge two php Doctrine 2 ArrayCollection()

Question

Is there any convenience method that allows me to concatenate two Doctrine ArrayCollection()? something like:

$collection1 = new ArrayCollection();
$collection2 = new ArrayCollection();

$collection1->add($obj1);
$collection1->add($obj2);
$collection1->add($obj3);

$collection2->add($obj4);
$collection2->add($obj5);
$collection2->add($obj6);

$collection1->concat($collection2);

// $collection1 now contains {$obj1, $obj2, $obj3, $obj4, $obj5, $obj6 }

I just want to know if I can save me iterating over the 2nd collection and adding each element one by one to the 1st collection.

Thanks!

Answer 1

You can simply do:

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

Answer 2

You still need to iterate over the Collections to add the contents of one array to another. Since the ArrayCollection is a wrapper class, you could try merging the arrays of elements while maintaining the keys, the array keys in $collection2 override any existing keys in $collection1 using a helper function below:

$combined = new ArrayCollection(array_merge_maintain_keys($collection1->toArray(), $collection2->toArray())); 

/**
 *  Merge the arrays passed to the function and keep the keys intact.
 *  If two keys overlap then it is the last added key that takes precedence.
 * 
 * @return Array the merged array
 */
function array_merge_maintain_keys() {
    $args = func_get_args();
    $result = array();
    foreach ( $args as &$array ) {
        foreach ( $array as $key => &$value ) {
            $result[$key] = $value;
        }
    }
    return $result;
}

Answer 3

Using Clousures PHP5 > 5.3.0

$a = ArrayCollection(array(1,2,3));
$b = ArrayCollection(array(4,5,6));

$b->forAll(function($key,$value) use ($a){ $a[]=$value;return true;});

echo $a.toArray();

array (size=6) 0 => int 1 1 => int 2 2 => int 3 3 => int 4 4 => int 5 5 => int 6

Answer 4

Based on Yury Pliashkou's comment:

function addCollectionToArray( $array , $collection ) {
    $temp = $collection->toArray();
    if ( count( $array ) > 0 ) {
        if ( count( $temp ) > 0 ) {
            $result = array_merge( $array , $temp );
        } else {
            $result = $array;
        }
    } else {
        if ( count( $temp ) > 0 ) {
            $result = $temp;
        } else {
            $result = array();
        }
    }
    return $result;
}

Maybe you like it... maybe not... I just thought of throwing it out there just in case someone needs it.

Answer 5

Better (and working) variant for me:

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

Answer 6

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.