Auto Rule Inferring

Learn how Laravel Data automatically infers validation rules from property types

The package will automatically infer validation rules from the data object. For example, for the following data class:

class ArtistData extends Data{
    public function __construct(
        public string $name,
        public int $age,
        public ?string $genre,
    ) {
    }
}

The package will generate the following validation rules:

[
    'name' => ['required', 'string'],
    'age' => ['required', 'integer'],
    'genre' => ['nullable', 'string'],
]

All these rules are inferred by RuleInferrers, special classes that will look at the types of properties and will add rules based upon that.

Configuring rule inferrers

Rule inferrers are configured in the data.php config file:

/*
 * Rule inferrers can be configured here. They will automatically add
 * validation rules to properties of a data object based upon
 * the type of the property.
 */
'rule_inferrers' => [
    Spatie\LaravelData\RuleInferrers\SometimesRuleInferrer::class,
    Spatie\LaravelData\RuleInferrers\NullableRuleInferrer::class,
    Spatie\LaravelData\RuleInferrers\RequiredRuleInferrer::class,
    Spatie\LaravelData\RuleInferrers\BuiltInTypesRuleInferrer::class,
    Spatie\LaravelData\RuleInferrers\AttributesRuleInferrer::class,
],

By default, five rule inferrers are enabled:

Built-in rule inferrers

SometimesRuleInferrer

Will add a sometimes rule when the property is optional.

class ArtistData extends Data{
    public function __construct(
        public string $name,
        public Optional|int $age,
    ) {
    }
}

// Rules: ['name' => ['required', 'string'], 'age' => ['sometimes', 'integer']]

NullableRuleInferrer

Will add a nullable rule when the property is nullable.

class ArtistData extends Data{
    public function __construct(
        public string $name,
        public ?string $genre,
    ) {
    }
}

// Rules: ['name' => ['required', 'string'], 'genre' => ['nullable', 'string']]

RequiredRuleInferrer

Will add a required rule when the property is not nullable.

class ArtistData extends Data{
    public function __construct(
        public string $name,
        public int $age,
    ) {
    }
}

// Rules: ['name' => ['required', 'string'], 'age' => ['required', 'integer']]

BuiltInTypesRuleInferrer

Will add rules which are based upon the built-in PHP types:

• An int or float type will add the numeric rule
• A bool type will add the boolean rule
• A string type will add the string rule
• An array type will add the array rule

namespace Spatie\LaravelData\RuleInferrers;

use BackedEnum;
use Spatie\LaravelData\Attributes\Validation\ArrayType;
use Spatie\LaravelData\Attributes\Validation\BooleanType;
use Spatie\LaravelData\Attributes\Validation\Enum;
use Spatie\LaravelData\Attributes\Validation\Numeric;
use Spatie\LaravelData\Attributes\Validation\StringType;
use Spatie\LaravelData\Support\DataProperty;
use Spatie\LaravelData\Support\Validation\PropertyRules;
use Spatie\LaravelData\Support\Validation\RequiringRule;
use Spatie\LaravelData\Support\Validation\ValidationContext;

class BuiltInTypesRuleInferrer implements RuleInferrer
{
    public function handle(
        DataProperty $property,
        PropertyRules $rules,
        ValidationContext $context,
    ): PropertyRules {
        if ($property->type->type->acceptsType('int')) {
            $rules->add(new Numeric());
        }

        if ($property->type->type->acceptsType('string')) {
            $rules->add(new StringType());
        }

        if ($property->type->type->acceptsType('bool')) {
            $rules->removeType(RequiringRule::class);

            $rules->add(new BooleanType());
        }

        if ($property->type->type->acceptsType('float')) {
            $rules->add(new Numeric());
        }

        if ($property->type->type->acceptsType('array')) {
            $rules->add(new ArrayType());
        }

        if ($enumClass = $property->type->type->findAcceptedTypeForBaseType(BackedEnum::class)) {
            $rules->add(new Enum($enumClass));
        }

        return $rules;
    }
}

AttributesRuleInferrer

Will make sure that rule attributes we described above will also add their rules.

use Spatie\LaravelData\Attributes\Validation\Max;

class ArtistData extends Data{
    public function __construct(
        #[Max(100)]
        public string $name,
    ) {
    }
}

// Rules: ['name' => ['required', 'string', 'max:100']]

Creating custom rule inferrers

It is possible to write your own rule inferrers. You can find more information here.