mapper.md

Mapper

In order to allow you to do custom mapping to generate an array from your collection you could create a class that implements the following interface:

Mapper

interface Mapper
{
    public function map(AbstractCollection $collection): array;
}

The map method should receive any implementation of the AbstractCollection and return a array.

DefaultMapper

To reduce code you can create your mapper classes by extending the DefaultMapper.

public function __construct(string ...$collectionClasses);

abstract protected function getCallers(string $collectionClass): ?MapperCallers;

The constructor should receive the full qualified name of your collection classes.

The getCallers method should be implemented. It will create a MapperCallers instance or null if the collection class is unknown in the context of your mapper.

The MapperCallers should receive two closures on the constructor.

When calling the mapper constructor make sure your getCallers returns for the collection classes you pass to the constructor, otherwise it will throw an exception.

Also, when calling the map method also make sure your collection instance is of one the classes you register in the constructor, otherwise it will throw an exception.

public function __construct(private Closure $fnGetId, private Closure $fnGetValue);

The $fnGetId closure should receive an instance of your collection item and return the identifier to use in the map result.

The $fnGetValue closure should receive an instance of your collection item and return the value to use in the map result.

Example

<?php
declare(strict_types=1);

use Kununu\Collection\AbstractCollection;
use Kununu\Collection\Mapper\DefaultMapper;
use Kununu\Collection\Mapper\MapperCallers;

final class MyCollectionItem
{
    public function __construct(public readonly int $key, public readonly string $value)
    {
    }
}

final class MyCollection extends AbstractCollection
{
}

final class MyMapper extends DefaultMapper
{
    protected function getCallers(string $collectionClass): ?MapperCallers
    {
        if (MyCollection::class === $collectionClass) {
            return new MapperCallers(
                fn(MyCollectionItem $item): string => sprintf('ID %s', $item->key), 
                fn(MyCollectionItem $item): string => $item->value
            );
        }

        return null;
    }    
}

$mapper = new MyMapper(MyCollection::class);

$map = $mapper->map(
    new MyCollection(
        new MyCollectionItem(1, 'Item 1'),
        new MyCollectionItem(2, 'Item 2')
    )
);
/*
Value of $map:
[
    'ID 1' => 'Item 1',
    'ID 2' => 'Item 2'
]
*/

$mapper->map(new AnotheCollection());
// Will throw exception because mapper could not create a `MapperCallers` instance
// for this collection class


$mapper = new MyMapper(AnotheCollection::class);
// Will throw exception because mapper could not create a `MapperCallers` instance
// for this collection class