在Laravel中使用Ajax请求更新数据库时出现500错误

Question

在具有以下功能的laravel中使用ajax请求更新数据库时，出现500错误。

public function downloadsnippet(Request $request){

    $snippet_id = $request->post('snippet_id');

    if ($request->ajax()) {

     $getsnippet = Constant_model::getDataOneColumn('snippets', 'id', $snippet_id);

     $total_downloads = $getsnippet[0]->total_downloads;

     $data = [     
            'total_downloads' => $total_downloads+1
             ];

      $mydata =  Constant_model::updateData('snippets',$data,$snippet_id);

      return $mydata;
    }

}

updateData函数是

public function updateData($table, $data, $id)
{
   DB::table($table)->where('id', $id)->update($data);
   return true;
}