Laravel 8模型层面能否设置数据表列（如ENUM）的允许值？

当然可以在Laravel 8的模型层面实现ENUM类型列的允许值校验，下面是几种常用的实现方式：

方法一：定义常量+监听模型保存事件 #

先在模型中定义该ENUM列的所有允许值常量，再通过模型的saving事件在保存前自动校验：

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use InvalidArgumentException;

class Post extends Model
{
    // 定义ENUM允许的常量值
    const STATUS_DRAFT = 'draft';
    const STATUS_PUBLISHED = 'published';
    const STATUS_ARCHIVED = 'archived';
    public const ALLOWED_STATUSES = [self::STATUS_DRAFT, self::STATUS_PUBLISHED, self::STATUS_ARCHIVED];

    protected static function boot()
    {
        parent::boot();

        // 监听保存事件，校验状态值
        static::saving(function ($model) {
            if (!in_array($model->status, self::ALLOWED_STATUSES)) {
                throw new InvalidArgumentException(
                    "状态值无效，允许的值为: " . implode(', ', self::ALLOWED_STATUSES)
                );
            }
        });
    }
}

方法二：使用自定义类型转换（Cast） #

通过自定义Cast类，在赋值时自动校验值的合法性：

1. 创建自定义Cast类：

namespace App\Casts;

use Illuminate\Contracts\Database\Eloquent\CastsAttributes;
use InvalidArgumentException;

class EnumStatusCast implements CastsAttributes
{
    // 定义允许的ENUM值
    protected $allowedValues = ['draft', 'published', 'archived'];

    public function get($model, $key, $value, $attributes)
    {
        return $value;
    }

    public function set($model, $key, $value, $attributes)
    {
        if (!in_array($value, $this->allowedValues)) {
            throw new InvalidArgumentException(
                "无效的状态值，允许的值为: " . implode(', ', $this->allowedValues)
            );
        }
        return $value;
    }
}

2. 在模型中绑定该Cast到对应列：

namespace App\Models;

use App\Casts\EnumStatusCast;
use Illuminate\Database\Eloquent\Model;

class Post extends Model
{
    protected $casts = [
        'status' => EnumStatusCast::class,
    ];
}

方法三：重写模型save方法结合验证器 #

利用Laravel自带的验证器，在模型保存前做校验：

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Validation\ValidationException;
use Illuminate\Support\Facades\Validator;

class Post extends Model
{
    public const ALLOWED_STATUSES = ['draft', 'published', 'archived'];

    public function save(array $options = [])
    {
        $validator = Validator::make($this->attributes, [
            'status' => 'required|in:' . implode(',', self::ALLOWED_STATUSES),
        ]);

        if ($validator->fails()) {
            throw new ValidationException($validator);
        }

        return parent::save($options);
    }
}

内容的提问来源于stack exchange，提问作者Čamo