Override all object properties type to string

[mvorisek]

I am author of hintable model fields for ORM project.

The hintable magic works by hinting IDE static type - see https://github.com/mvorisek/atk4-hintable-mirror/blob/1.1.0/src/Data/HintableModelTrait.php#L232 - but in reality:

• completely different object is returned
• with the same and only property names
• all properties returns string

Example:

class User extends Model
{
    use HintableModelTrait;

    /** @var int */
    public $userId;

    ...
}

$u = new User();

var_dump($u->userId); // prints int(5)
var_dump($u->fieldName()->userId); // prints string(6) "userId"

My question is, how to hint PHPStan, that:

$u->fieldName()->userId

is string but keep all other PHPStan checks like visibility, if property is defined etc.

I think I need to write a PHPStan extension, but I would be very grateful to have some help/example to start with.

Test cases:

1. is string

echo strtolower($u->fieldName()->userId); // currently PHPStan warns, because it thinks userId is int

2. undefined property

echo strtolower($u->fieldName()->notExisting); // keep PHPStan warning

[ondrejmirtes]

What object is returned when $u->fieldName() is accessed?

[mvorisek]

https://github.com/mvorisek/atk4-hintable-mirror/blob/1.1.0/src/Data/MagicModelField.php#L11

[ondrejmirtes]

So:

1. Make MagicModelField generic, it will carry the class it's describing (User in your example).
2. Create a dynamic return type extension (https://phpstan.org/developing-extensions/dynamic-return-type-extensions) that describes Model::fieldName().
3. This extension needs to return new GenericObjectType(MagicModelField::Class, [new ObjectType('X')]) when X::fieldName() is called.
4. Write PropertiesClassReflectionExtension (https://phpstan.org/developing-extensions/class-reflection-extensions#properties-class-reflection-extensions) for MagicModelField. In the hasProperty method, you'll inspect the incoming ClassReflection (it should be for MagicModelField), and you'll ask about ClassReflection::getActiveTemplateTypeMap(). You should ask about the template type from 1) and obtain X that way.
5. Ask for ReflectionProvider in the constructor in your implementation of PropertiesClassReflectionExtension.
6. PropertiesClassReflectionExtension::hasProperty() should return true for $propertyName that exists on X. You can ask X's ClassReflection that you obtain from ReflectionProvider in 5).
7. PropertiesClassReflectionExtension::getProperty() can simply delegate the call to ClassReflection::getProperty() of X.

[ondrejmirtes]

2. Yeah but I'm not sure you'd want to write this over and over:

/** @extends Model<User> */
class User extends Model { ... }

[ondrejmirtes]

I replied to 4. at the linked commit.

[mvorisek]

Thank you very much for your comprehensive and quick reply, it works well - here is a result: https://github.com/mvorisek/atk4-hintable-mirror/blob/1.1.1/src/Phpstan/MagicReflectionExtension.php#L16

[mvorisek]

one more question - is it possible to distribute PHPStan extension so it is autoincluded/registered in projects where the library is used/required by composer?

[ondrejmirtes]

Yes: https://github.com/phpstan/extension-installer

[ondrejmirtes]

Thanks to this guide, $u->fieldName() will know only about valid properties of $u.

A little correction: Because you need $u->fieldName()->userId to be string, you need to return your own PropertyReflection implementation from getProperty.