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
{
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'],
]
The same happens when a property is made optional:
class AlbumData extends Data
{
public function __construct(
public string $title,
public 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.