PHP use ENUM in Attributes

Question

Look at the following code:

<?php

enum Types:string {
    case A = 'a';
    case B = 'b';
}

#[Attribute(Attribute::TARGET_CLASS)]
class MyAttribute {
    public function __construct(public readonly array $mapping)
    {
    }
}

#[MyAttribute(mapping: [Types::A->value => ''])]
class Entity {

}

It has error Constant expression contains invalid operations. I would like to use Enum value in my attribute for defining configuration. Seem like it is bug in php. Should it be reported or something?

112Legion · Accepted Answer · 2022-11-18T12:01:59.557

The problem is that when we call Types::A->value it actually creates instance of an enum, which is not a constant value. To solve this problem define a constant and reference it.

<?php

abstract class Type {
    public const A = 'a';
    public const B = 'b';
}

enum TypesEnum:string {
    case A = Type::A;
    case B = Type::B;
}

#[Attribute(Attribute::TARGET_CLASS)]
class MyAttribute {
    public function __construct(public readonly array $mapping)
    {
    }
}

#[MyAttribute(mapping: [Type::A => ''])]
class Entity {

}

Watch out for this issue in php

PHP use ENUM in Attributes

1 Answers1