Larave会默认将表单提交过来的空字符串自动转为null, 我们可以自行去掉这个这个配置
在app/Http/Kernel.php文件中注释掉对应的ConvertEmptyStringsToNull中间件
<?php
namespace App\Http;
use App\Http\Middleware\AdminOperationLog;
use Illuminate\Foundation\Http\Kernel as HttpKernel;
class Kernel extends HttpKernel
{
/**
* The application's global HTTP middleware stack.
*
* These middleware are run during every request to your application.
*
* @var array
*/
protected $middleware = [
\App\Http\Middleware\TrustProxies::class,
\App\Http\Middleware\CheckForMaintenanceMode::class,
\Illuminate\Foundation\Http\Middleware\ValidatePostSize::class,
\App\Http\Middleware\TrimStrings::class,
// \Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class, // 空字符转null中间件
];
