Skip to main content
A data object can contain other data objects or collections of data objects. The package will make sure that also for these data objects validation rules will be generated. Let’s take a look again at the data object from the nesting section: 
class AlbumData extends Data
{
    public function __construct(
        public string $title,
        public ArtistData $artist,
    ) {
    }
}
The validation rules for this class would be: 
[
    'title' => ['required', 'string'],
    'artist' => ['array'],
    'artist.name' => ['required', 'string'],
    'artist.age' => ['required', 'integer'],
]

​
Validating a nested collection of data objects

When validating a data object like this: 
class AlbumData extends Data
{
    /**
    * @param array<int, SongData> $songs
    */
    public function __construct(
        public string $title,
        public array $songs,
    ) {
    }
}
In this case the validation rules for AlbumData would look like this: 
[
    'title' => ['required', 'string'],
    'songs' => ['present', 'array', new NestedRules()],
]
The NestedRules class is a Laravel validation rule that will validate each item within the collection for the rules defined on the data class for that collection.

​
Nullable and Optional nested data

If we make the nested data object nullable, the validation rules will change depending on the payload provided: 
class AlbumData extends Data
{
    public function __construct(
        public string $title,
        public ?ArtistData $artist,
    ) {
    }
}
If no value for the nested object key was provided or the value is null, the validation rules will be: 
[
    'title' => ['required', 'string'],
    'artist' => ['nullable'],
]
If, however, a value was provided (even an empty array), the validation rules will be: 
[
    'title' => ['required', 'string'],
    'artist' => ['array'],
    'artist.name' => ['required', 'string'],
    'artist.age' => ['required', 'integer'],
]

​
Optional nested data

The same happens when a property is made optional: 
use Spatie\LaravelData\Optional;

class AlbumData extends Data
{
    public function __construct(
        public string $title,
        public Optional|ArtistData $artist,
    ) {
    }
}
There’s a small difference compared against nullable, though. When no value was provided for the nested object key, the validation rules will be: 
[
    'title' => ['required', 'string'],
    'artist' => ['present', 'array', new NestedRules()],
]
However, when a value was provided (even an empty array or null), the validation rules will be: 
[
    'title' => ['required', 'string'],
    'artist' => ['array'],
    'artist.name' => ['required', 'string'],
    'artist.age' => ['required', 'integer'],
]
We’ve written a blog post on the reasoning behind these variable validation rules based upon payload. And they are also the reason why calling getValidationRules on a data object always requires a payload to be provided.