Create Enum from Name in PHP

user_2989952 0
Viewed 437

In PHP 8.1, BackedEnum offer a from and tryFrom method to get an enum from a value. How can the same be achieved by non backed enums?

Example BackedEnum:

enum MainType: string
{
    case Full = 'a';
    case Major = 'b';
    case Minor = 'c';
}

var_dump(MainType::tryFrom('a')); // MainType::Full
var_dump(MainType::tryFrom('d')); // null

However this doesn't exist for regular enums.

How would I retrieve a "normal" Enum by name, like:

enum MainType
{
    case Full;
    case Major;
    case Minor;
}

$name = (MainType::Full)->name
var_dump(name); // (string) Full

One option I've found is to simply add a tryFromName function, accepting a string and looping over all the cases like this:

enum MainType
{
    case Full;
    case Major;
    case Minor;

    public static function tryFromName(string $name): ?static
    {
        foreach (static::cases() as $case) {
            if ($case->name === $name) {
                return $case;
            }
        }

        return null;
    }
}

$name = (MainType::Full)->name
var_dump(name); // (string) Full
var_dump(MainType::tryFromName($name)); // MainType::Full

This works, however it seams counter intuitive to enable a foreach loop going over all possibilities just to create an enum.

Therefore the question is, what is the right way to get an Enum in PHP from the name.

enums php
2 Answers

You can use Reflection:

trait Enum {

    public static function tryFromName(string $name): ?static
    {
        $reflection = new ReflectionEnum(static::class);

        return $reflection->hasCase($name)
            ? $reflection->getCase($name)->getValue()
            : null;
    }

}

enum Foo {
    use Enum;

    case ONE;
    case TWO;
}

var_dump( Foo::tryFromName('TWO')   ); // enum(Foo::TWO)
var_dump( Foo::tryFromName('THREE') ); // null

Works also for Backed Enums.

user_16279450
user_11255560
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