README

Bidirectional mapper for PHP with support for generics, array shapes and nullable types. For each class, input and output mappers are generated at runtime and cached on disk. The mappers are generated only once and then reused on subsequent requests. The generated mappers are highly optimized for performance and designed to be human readable. You can see examples of generated mappers in the tests directory: input mapper, output mapper.

Installation:

composer require shipmonk/input-mapper

Features

Built-in mappers

Input Mapper comes with built-in mappers for the following types:

array, bool, float, int, mixed, string, list
positive-int, negative-int, int<TMin, TMax>, non-empty-string, non-empty-list
array<V>, array<K, V>, list<V>, non-empty-list<V>
array{K1: V1, ...}
?T, Optional<T>
DateTimeInterface, DateTimeImmutable
BackedEnum
and most importantly classes with public constructor

All built-in mappers support both input (array → object) and output (object → array) directions.

You can write your own mappers or replace the default mappers with your own.

Built-in validators

Input Mapper comes with some built-in validators (input mapping only):

int validators:
- AssertInt16
- AssertInt32
- AssertIntRange
- AssertPositiveInt
- AssertNegativeInt
- AssertNonNegativeInt
- AssertNonPositiveInt
- AssertIntMultipleOf
float validators:
- AssertFloatRange
- AssertPositiveFloat
- AssertNegativeFloat
- AssertNonNegativeFloat
- AssertNonPositiveFloat
- AssertFloatMultipleOf
string validators:
- AssertStringLength
- AssertStringMatches
- AssertStringNonEmpty
- AssertUrl
list validators:
- AssertListItem
- AssertListLength
- AssertUniqueItems (compares items by ===)
date time validators:
- AssertDateTimeRange

You can write your own validators if you need more.

Usage:

Write Input Class

To use Input Mapper, write a class with a public constructor and add either native or PHPDoc types to all constructor parameters.

Optional fields can either be marked with #[Optional] attribute (allowing you to specify a default value), or if you need to distinguish between default and missing values, you can wrap the type with ShipMonk\InputMapper\Runtime\Optional class.

use ShipMonk\InputMapper\Compiler\Attribute\Optional;

class Person
{
    public function __construct(
        public readonly string $name,

        public readonly int $age,

        #[Optional]
        public readonly ?string $email,

        /** @var list<string> */
        public readonly array $hobbies,

        /** @var list<self> */
        #[Optional(default: [])]
        public readonly array $friends,
    ) {}
}

By default, any extra properties are not allowed. You can change that by adding #[AllowExtraKeys] over the class.

Map Input

To map input data (e.g. JSON) to objects, use MapperProvider:

$tempDir = __DIR__ . '/temp/input-mapper'; // writable, project-local directory
$autoRefresh = true; // MUST be set to false in production
$mapperProvider = new ShipMonk\InputMapper\Runtime\MapperProvider($tempDir, $autoRefresh);
$mapper = $mapperProvider->getInputMapper(Person::class);

try {
    $person = $mapper->map([
        'name' => 'John',
        'age' => 30,
        'hobbies' => ['hiking', 'reading'],
        'friends' => [
            [
                'name' => 'Jane',
                'age' => 28,
                'hobbies' => ['hiking', 'reading'],
            ],
            [
                'name' => 'Jack',
                'age' => 28,
                'hobbies' => ['hiking', 'reading'],
            ],
        ],
    ]);
} catch (\ShipMonk\InputMapper\Runtime\Exception\MappingFailedException $e) {
    // $e->getMessage() // programmer readable error message in English
    // $e->getPath() // path of the problematic field for example ['friends', 0, 'name']
    // ...
}

Generated mappers are PHP files that get included — point tempDir at a directory owned by your application, not a shared world-writable location such as the system temporary directory, so that no other local user can pre-create it and plant files that your application would then execute.

Map Output

To convert objects back to plain arrays (e.g. for JSON serialization), use the same MapperProvider:

$mapper = $mapperProvider->getOutputMapper(Person::class);

$data = $mapper->map($person);
// ['name' => 'John', 'age' => 30, 'email' => null, 'hobbies' => ['hiking', 'reading'], 'friends' => [...]]

The output mapper converts objects to arrays, enums to their backing values, DateTimeImmutable to formatted strings, and Optional properties are omitted from the output when not defined. All types supported by input mapping are also supported by output mapping.

Adding Validation Rules

You can add validation rules by adding attributes to constructor parameters.

For example, to validate that age is between 18 and 99, you can add the AssertIntRange attribute to the constructor parameter:

use ShipMonk\InputMapper\Compiler\Validator\Int\AssertIntRange;

class Person
{
    public function __construct(
        public readonly string $name,

        #[AssertIntRange(gte: 18, lte: 99)]
        public readonly int $age,
    ) {}
}

Renaming keys

If the input keys do not match the property names, you can use the #[SourceKey] attribute to specify the key name:

use ShipMonk\InputMapper\Compiler\Attribute\SourceKey;

class Person
{
    public function __construct(
        #[SourceKey('full_name')]
        public readonly string $name,
    ) {}
}

To rename keys globally — e.g. camelCase PHP properties ↔ snake_case wire keys — configure a PropertyNameTransformer on the DefaultMapperCompilerFactoryProvider. The transform is applied in both directions (input lookup and output emission), and #[SourceKey] always takes precedence over it on properties where it is set:

use ShipMonk\InputMapper\Compiler\MapperFactory\DefaultMapperCompilerFactoryProvider;
use ShipMonk\InputMapper\Compiler\PropertyNameTransformer\CamelToSnakeCasePropertyNameTransformer;
use ShipMonk\InputMapper\Runtime\MapperProvider;

$provider = new MapperProvider(
    tempDir: __DIR__ . '/temp',
    mapperCompilerFactoryProvider: new DefaultMapperCompilerFactoryProvider(
        new CamelToSnakeCasePropertyNameTransformer(),
    ),
);

The built-in CamelToSnakeCasePropertyNameTransformer handles common acronym boundaries (HTTPServer → http_server, parseURL → parse_url). Implement PropertyNameTransformer yourself for other conventions.

Parsing polymorphic classes (subtypes with a common parent)

If you need to parse a hierarchy of classes, you can use the #[Discriminator] attribute. (The discriminator field does not need to be mapped to a property if #[AllowExtraKeys] is used.)

use ShipMonk\InputMapper\Compiler\Attribute\Discriminator;

#[Discriminator(
    key: 'type', // key to use for mapping
    mapping: [
        'car' => Car::class,
        'truck' => Truck::class,
    ]
)]
abstract class Vehicle {
    public function __construct(
        public readonly string $type,
    ) {}
}

class Car extends Vehicle {

    public function __construct(
        string $type,
        public readonly string $color,
    ) {
        parent::__construct($type);
    }

}

class Truck extends Vehicle {

    public function __construct(
        string $type,
        public readonly string $color,
    ) {
        parent::__construct($type);
    }

}

or, with enum:

use ShipMonk\InputMapper\Compiler\Attribute\Discriminator;

enum VehicleType: string {
    case Car = 'car';
    case Truck = 'truck';
}

#[Discriminator(
    key: 'type', // key to use for mapping
    mapping: [
        VehicleType::Car->value => Car::class,
        VehicleType::Truck->value => Truck::class,
    ]
)]
abstract class Vehicle {
    public function __construct(
        VehicleType $type,
    ) {}
}

class Car extends Vehicle {

    public function __construct(
        VehicleType $type,
        public readonly string $color,
    ) {
        parent::__construct($type);
    }

}

class Truck extends Vehicle {

    public function __construct(
        VehicleType $type,
        public readonly string $color,
    ) {
        parent::__construct($type);
    }

}

Using custom mappers

To map a class with your own hand-written mapper, implement the Mapper interface and register a factory for the class with MapperProvider:

use ShipMonk\InputMapper\Runtime\Mapper;
use ShipMonk\InputMapper\Runtime\MapperProvider;

/**
 * @implements Mapper<mixed, MyCustomClass>
 */
class MyCustomClassInputMapper implements Mapper
{
    public function map(mixed $data, array $path = []): MyCustomClass
    {
        return MyCustomClass::createFrom($data);
    }
}

$mapperProvider->registerInputFactory(MyCustomClass::class, function () {
    return new MyCustomClassInputMapper();
});

Use registerOutputFactory() the same way to customize the output direction. The factory callable receives the concrete class name, the list of generic inner mappers, and the MapperProvider instance, so it can delegate to other mappers if needed. A factory may also be registered for an interface or parent class — it then applies to all of its implementations.

Customizing default mappers inferred from types

To customize how default mappers are inferred from types, you need to implement ShipMonk\InputMapper\Compiler\MapperFactory\MapperCompilerFactory and MapperCompilerFactoryProvider.

Then pass your factory provider to the MapperProvider — the same provider serves both the input and output directions:

$mapperProvider = new ShipMonk\InputMapper\Runtime\MapperProvider(
    tempDir: $tempDir,
    autoRefresh: $autoRefresh,
    mapperCompilerFactoryProvider: new MyCustomMapperCompilerFactoryProvider(),
);

Contributing

Check your code by composer check
Autofix coding-style by composer fix:cs
All functionality must be tested

shipmonk / input-mapper

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