PHP Enumerated Type

HasEnums.php

trait HasEnums
{
    /**
     * The array of enumerators of a given group.
     *
     * @param null|string $group
     * @return array
     */
    static function enums($group = null)
    {
        $constants = (new ReflectionClass(get_called_class()))->getConstants();

        if ($group) {
            return array_filter($constants, function ($key) use ($group) {
                return strpos($key, $group.'_') === 0;
            }, ARRAY_FILTER_USE_KEY);
        }

        return $constants;
    }

    /**
     * Check if the given value is valid within the given group.
     *
     * @param mixed $value
     * @param null|string $group
     * @return bool
     */
    static function isValidEnumValue($value, $group = null)
    {
        $constants = static::enums($group);

        return in_array($value, $constants);
    }

    /**
     * Check if the given key exists.
     *
     * @param mixed $key
     * @return bool
     */
    static function isValidEnumKey($key)
    {
        return array_key_exists($key, static::enums());
    }
}

I came up with something almost identical a time ago!

I also use a method called const (never thought of a better name) in the trait that checks if an object's auto-detected attribute is equal to a constant in the model.

public function const($constant)
{
    $constants = (new ReflectionClass(get_called_class()))->getConstants();

    if (isset($constants[$constant])) {
        $attr = strtolower(explode('_', $constant)[0]);

        return $this->$attr == $constants[$constant];
    }

    return false;
}

So I can do something like:

$order->const('TYPE_DINE_IN');

Which is equivalent to:

$order->type == App\Models\Order::TYPE_DINE_IN;

Yes, I like to put all my models in its own namespace, and with this, I can avoid namespacing the constants in, for example, Blade views:

// normally
@if ($order->type == App\Models\Order::TYPE_TAKEAWAY)
    // some code
@endif

// with trait
@if ($order->const('TYPE_TAKEAWAY'))
    // some code
@endif

Of course, this method has some shortcomings —like if your attribute has a composite name like $order->delivery_status and your constants are in the form of DELIVERY_STATUS_SENT— because the method expects a single word in the attribute name, but it works for me the 99% of the time.