Laravel 5“内部服务器错误”(500),Ajax表单提交

我对我的 ajax 在my中提交表单 Laravel 5 项目我的浏览器控制台中出现以下错误:

 Failed to load resource: the server responded with a status of 500 (Internal Server Error)

我尝试了许多在其他帖子和网站上找到的建议,但都没有成功。以下是我的Ajax:

$.ajax({'url': './subscribe' 
    ,'data' : {
                "_token": $('meta[name="csrf-token"]').attr('content')
                ,"email" : $('#subscribe-email-input').val() 
            }
    ,'method': 'POST' 
    ,'success': function(data){
        console.log( data );
    }
    ,'error': function(data){
        console.log( 'oops', data );
    }
});

我在我的 routes/web.php 文件:

Route::post('subscribe', ['uses' => 'SubscribeController@validate', 'as' => 'subscribe.route']);

控制器非常简单:

class SubscribeController extends Controller
{   
    /*
    *   Get email address from DB if exists
    *
    *   @param string email, email address to search and return data from DB
    *
    *   @returns $email
    */
    public function validate ( Request $request )
    {
        $email = addslashes($request->email) ;

        if ( $email ) 
        {           
            $email = \App\Subscribe::where('email', '=', $email)->get();

            if ( $email->isEmpty() ) 
            {
                self::executeInsertQuery ( $email );
                return json_encode( array('body' => 'You have subscribed!') );
            } else {
                return json_encode( array('body' => 'You are already subscribed!') );
            }

        }       
    }
}

我会在 self::executeInsertQuery(...) 但考虑到 subscribe 路线似乎还没有到达 validate 方法

如果您对如何解决此问题有任何建议,我们将不胜感激!!提前感谢您!