Inheritance Mapping

A source or target class may inherit from another class.

When creating the mapping, AutoMapper can determine the correct mapping by using the inheritance information from the #[Mapper] attribute.

#[Mapper(discriminator: new Discriminator(
    mapping: [
        DogDto::class => Dog::class,
        CatDto::class => Cat::class,
    ]
))]
abstract class Pet
{
    /** @var string */
    public $name;

    /** @var PetOwner */
    public $owner;
}

When mapping a Pet object, AutoMapper will automatically determine the correct class to instantiate based on the instance of the property.

If it's a Dog class it will map to a DogDto class, and if it's a Cat class it will map to a CatDto class.

Note that the key is the target class, and the value is the source class.

Mapping to an array

When mapping to an array there is no class to determine the correct mapping. In this case, instead of using the instance of the object, AutoMapper will use the value of a specific property to determine the correct mapping.

#[Mapper(target: 'array', discriminator: new Discriminator(
    property: 'type',
    mapping: [
        'dog' => Dog::class,
        'cat' => Cat::class,
    ]
))]
abstract class Pet
{
    /** @var string */
    public $name;

    /** @var PetOwner */
    public $owner;
}

In this example, when mapping to / from an array, AutoMapper will write / read the type property to determine the correct mapping.

If the type property is equal to dog, it will map to / from the Dog class, and if it's equal to cat, it will map to / from the Cat class.

Note

It also possible to use the same principle when mapping to a data structure that don't have inheritance.