ifnex/04_Laravel/app/Models/SystemSetting.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;

class SystemSetting extends Model
{
    protected $fillable = [
        'key',
        'value',
        'description',
        'updated_by',
    ];

    protected function casts(): array
    {
        return [
            'value' => 'decimal:4',
        ];
    }

    public function updatedBy(): BelongsTo
    {
        return $this->belongsTo(User::class, 'updated_by');
    }

    public static function get(string $key, $default = null)
    {
        $setting = static::where('key', $key)->first();
        return $setting ? $setting->value : $default;
    }

    public static function set(string $key, $value, ?string $description = null, ?int $updatedBy = null): void
    {
        static::updateOrCreate(
            ['key' => $key],
            [
                'value' => $value,
                'description' => $description,
                'updated_by' => $updatedBy,
            ]
        );
    }
}