oracle存空字符串怎么会变成null

Posted 2023-05-07

参考技术A sqlserver中可用isnull函数： select isnull(null,''); oracle中可用nvl函数： select nvl(null,'') from dual; mysql中可用ifnull函数： select ifnull(null,'');本回答被提问者采纳

php laravel 空字符串变成了null

原因

app/Http/Kernel.php下

系统使用了这样的一个中间件

//        \\Illuminate\\Foundation\\Http\\Middleware\\ConvertEmptyStringsToNull::class,

注释掉就可以解决

如果你对源码感兴趣

<?php

namespace Illuminate\\Foundation\\Http\\Middleware;

use Closure;

class ConvertEmptyStringsToNull extends TransformsRequest

    /**
     * All of the registered skip callbacks.
     *
     * @var array
     */
    protected static $skipCallbacks = [];

    /**
     * Handle an incoming request.
     *
     * @param  \\Illuminate\\Http\\Request  $request
     * @param  \\Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    
        foreach (static::$skipCallbacks as $callback) 
            if ($callback($request)) 
                return $next($request);
            
        

        return parent::handle($request, $next);
    

    /**
     * Transform the given value.
     *
     * @param  string  $key
     * @param  mixed  $value
     * @return mixed
     */
    protected function transform($key, $value)
    
        return is_string($value) && $value === '' ? null : $value;
    

    /**
     * Register a callback that instructs the middleware to be skipped.
     *
     * @param  \\Closure  $callback
     * @return void
     */
    public static function skipWhen(Closure $callback)
    
        static::$skipCallbacks[] = $callback;
    

可以看到是因为他

protected function transform($key, $value)

    return is_string($value) && $value === '' ? null : $value;