Callbacks

Callbacks

The optional third argument of Mapper::map() receives every result entry and returns the value to store.

$result = Mapper::map($data, $schema, function ($key, $value) {
    if ($key === 'email') {
        return strtolower($value);
    }

    return $value;
});

How it is called

• Arguments: the result key (string or int) and the mapped value.
• The key of a collection is passed without the [] suffix.
• Nested schemas are processed first: the callback sees each child entry, then the parent key with the already transformed array.
• For a collection, the callback sees each column (a list) and then the merged rows.
• Any callable works: closures, function names, [ClassName::class, 'method'] and invokable objects.

// Schema: ['id' => '@data/id', 'lines[]' => ['sku' => '@data/items/*/sku']]
// Calls, in order:
// ('id', 10)
// ('sku', ['A', 'B'])
// ('lines', [['sku' => 'A'], ['sku' => 'B']])

Tips

• Always return $value for keys you do not change.
• Key names can repeat at different levels. Check the value type as well as the key when that matters.
• A schema with integer keys passes integers to the callback. Declare the key parameter without a type, or as int|string on PHP 8, when you use such schemas.