PHP using ENUM in properties

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 {

}

Error Constant expression contains invalid operation. I want to use enum values ​​in my properties to define the configuration. Looks like this is a bug in php. Should it be reported or what?

Answer 1

The problem is that when we call Types::A->value, it actually creates an instance of the 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 {

}

Pay attention to this problem in php