koel/app/Models/Setting.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Setting extends Model
{
    protected $primaryKey = 'key';

    public $timestamps = false;

    protected $guarded = [];

    /**
     * Get a setting value.
     *
     * @param string $key
     *
     * @return mixed
     */
    public static function get($key)
    {
        if ($record = self::find($key)) {
            return $record->value;
        }

        return '';
    }

    /**
     * Set a setting (no pun) value.
     *
     * @param string|array $key   The key of the setting, or an associative array of settings,
     *                            in which case $value will be discarded.
     * @param mixed        $value
     */
    public static function set($key, $value = null)
    {
        if (is_array($key)) {
            foreach ($key as $k => $v) {
                self::set($k, $v);
            }

            return;
        }

        self::updateOrCreate(compact('key'), compact('value'));
    }

    /**
     * Serialize the setting value before saving into the database.
     * This makes settings more flexible.
     *
     * @param mixed $value
     */
    public function setValueAttribute($value)
    {
        $this->attributes['value'] = serialize($value);
    }

    public function getValueAttribute($value)
    {
        return unserialize($value);
    }
}