Get Case from enum by string

Question

I search for a simple solution to get the case of an enum by a string. There are BackedEnums. For example:

<?php
enum Status: string
{
    case OK = "OK";
    case FAILED = "FAILED";
    ...
}
$status = Status::tryFrom("OK"); // or from("OK");

But I don't want to write the same word twice for getting that result. Is there a native way to get the case without having BackedEnums? I want something like:

<?php
enum Status
{
    case OK;
    case FAILED;
    ...
}
$status = Status::get("OK"); //returns Status::OK;

Or do I need to write my own funcionality for that? For example:

enum Status
{
    case OK;
    case FAILED;    
    public static function get(string $name): null|Status
    {
        $name = strtoupper(trim($name));
        if(empty($name))
            return null;

        foreach(Status::cases() as $status)
        {
            if($status->name == $name)
                return $status;
        }
        return null;
    }
}

Status::get("OK"); // -> Status::OK

Is there a better way to achieve the same?

joeb · Answer 1 · 2021-12-18T02:07:12.173

7

There is an internal name getter like this.

Status::OK->name;

This will return Ok

Status::OK->value;

This will return the value

To get the case from the value. Use this

$case = Status::tryFrom('Ok')

https://www.php.net/manual/en/backedenum.tryfrom.php

edited Dec 18 '21 at 02:07

answered Dec 17 '21 at 14:27

joeb

777
8
28

A slightly more verbose answer - https://stackoverflow.com/a/66208862/296555 – waterloomatt Dec 17 '21 at 14:30
my situation is different. I will try to make clear what I mean. I don't know the case in this example Status::OK What i have is a string with the name of the case: "OK" And now I try to find the simplest generic way to get the case for the string "OK" – philsak Dec 17 '21 at 15:40
Look at the last line of code i wrote: `Status::get("OK")`. lets suggest that i have a variabel `$test = "OK"` and now I want the matching case from status to that. Is it clear what I mean? – philsak Dec 17 '21 at 15:45
@philsak, I edited my original response. – joeb Dec 18 '21 at 02:08
`tryFrom` is not available in a non backed enum and op actually wants to simplify writing his `enums` without values (So non backed) – Tofandel Jun 22 '23 at 15:19

oikodomo · Accepted Answer · 2022-01-03T16:13:17.607

4

ReflectionEnum is the answer. In the rfc for enums in php8.1 is a chapter Reflection

There you have the method getCase(string $name) and in combination with getValue() you get the enum. With that function you can get the case via a string value.

Your Example would look like this:

$status = (new ReflectionEnum("Status"))->getCase("OK")->getValue();

Best used with an ExceptionHandler since the transmitted string, if not found, could end up in a ReflectionException

edited Jan 03 '22 at 16:13

answered Jan 03 '22 at 15:43

oikodomo

64
2

Valid value can be tested with `ReflectionEnum::hasCase` – hejdav Jun 08 '22 at 16:05
1

Class name is better to reference with `Status::class` constant instaed of literal. – hejdav Jun 08 '22 at 16:07
I made it more generic with `self::class` instead of the class name or string – Snapey Jun 16 '22 at 16:11

Tofandel · Answer 3 · 2023-06-22T15:13:40.963

Only a BackedEnum has the from and tryFrom methods available sadly, but they can easily be polyfilled, here is how you could write your own from and tryFrom in a trait for reusability

<?php

trait LazyEnum
{
    public static function tryFrom($caseName): ?self
    {
        $rc = new ReflectionEnum(self::class);
        return $rc->hasCase($caseName) ? $rc->getConstant($caseName) : null;
    }

    /**
     * @throws Exception
     */
    public static function from($caseName): self
    {
        return self::tryFrom($caseName) ?? throw new Exception('Enum '. $caseName . ' not found in ' . self::class);
    }

}


enum Test
{
    use LazyEnum;
    
    case FOO;
    case BAR;
}
var_dump(Test::tryFrom('FOO')); //enum(Test::FOO)
var_dump(Test::tryFrom('BAZ')); //NULL

score 0 · Answer 4 · answered Jun 30 '22 at 11:26

0

Instead of writing your own, you could use https://packagist.org/packages/henzeb/enumhancer

This will do for you what you need, and so much more.

answered Jun 30 '22 at 11:26

SomeOne_1

808
10
10

IMHO, it does really too much in the context of this question for a small feature, remember folks, each dependency you add means more maintenance down the road – Tofandel Jun 22 '23 at 15:17

Get Case from enum by string

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