Generate `numeric-string` type for model fields with a `decimal` cast

[ekisu]

Summary

Right now, model fields with a decimal type cast are annotated with the string type. This is correct, however typing them with a numeric-string type would help static analysis tools to better understand the code, and also to not flag valid code as incorrect. An example would be the following code:

/**
 * @property-read string $value
 */
readonly class ModelWithString {
    public function __construct(
        public string $value,
    ) {}
}

/**
 * @property-read numeric-string $value
 */
readonly class ModelWithNumericString {
    public function __construct(
        public string $value,
    ) {}
}

$a = new ModelWithString('1.23');
$result = $a->value + 3;

$b = new ModelWithNumericString('1.23');
$result2 = $b->value + 3;

In the above snippet, PHPStan flags the addition operation using the ModelWithString value property as invalid, but is able to check that the operation using the ModelWithNumericString value property is valid code (link to PHPStan's playground).

I am willing to work on this.

[mfn]

Can you check if you can change it via hooks (see readme)?

[ekisu]

I managed to change the properties' types to numeric-string using a model hook, however I couldn't quite figure out how to keep the same nullability as the original ones 🤔. Here's the code:

class ChangeDecimalCastsToNumericString implements ModelHookInterface
{
    public function run(ModelsCommand $command, Model $model): void
    {
        $casts = $model->getCasts();

        foreach ($casts as $fieldName => $cast) {
            if (!str_starts_with($cast, 'decimal')) {
                continue;
            }

            $command->setProperty($fieldName, 'numeric-string');
        }
    }
}

Even if it's possible to add this behavior as a model hook, I do believe it would be useful to have it by default, as it's widely supported by static analysis tools and IDEs/LSPs.

[barryvdh]

What is the support for this type?

[ekisu]

On static analysis tools, it's supported by:

• PHPStan, for a little over 4 years (commit)
• Psalm, since pretty much it's beginning (history dates to over 7 years)

On IDE/LSPs, it's supported by:

• Intelephense, for a little over an year (issue)
• PHPStorm, since 2020 (feature request)

---

On a second thought, I think that numeric will be more useful than numeric-string in this case, because the decimal cast allows us to write float|int into the property, and this isn't really allowed when using numeric-string, as shown in the following snippet (link to PHPStan's playground). Support should be pretty much the same/wider than numeric-string.

/**
 * @property string $value
 */
class ModelWithString {
    public function __construct(
        public string $value,
    ) {}
}

/**
 * @property numeric-string $value
 */
class ModelWithNumericString {
    public function __construct(
        public string $value,
    ) {}
}

/**
 * @property numeric $value
 */
class ModelWithNumeric {
    public function __construct(
        public string $value,
    ) {}
}

$a = new ModelWithString('1.23');
$a->value = $a->value + 3;
$a->value = '4.56';
$a->value = 4.56;

$b = new ModelWithNumericString('1.23');
$b->value = $b->value + 3;
$b->value = '4.56';
$b->value = 4.56;

$c = new ModelWithNumeric('1.23');
$c->value = $c->value + 3;
$c->value = '4.56';
$c->value = 4.56;