为什么提示 avatar_image_id 不存在呢？

exists:table,column

'avatar_image_id' => 'exists:images,id,

如果你想要验证在images表下user_id等于$userId时,avatar_image_id是否存在的话,你可以这样

 'avatar_image_id' => [
        Rule::exists('images')->where(function ($query) {
            $query->where('user_id', $userId);
        }),
    ],

message": "Method Illuminate\\Validation\\Rules\\Exists::__toString() must not throw an exception, caught ErrorException: Object of class Closure could not be converted to string",
    "code": 1,
    "status_code": 500,
    "debug": {
        "line": 0,
        "file": "/home/vagrant/code/larabbs/vendor/laravel/framework/src/Illuminate/Validation/ValidationRuleParser.php",
        "class": "Symfony\\Component\\Debug\\Exception\\FatalErrorException",

                'avatar_image_id'=>[
                        Rule::exists('images',function ($query){
                            $query->where('user_id',(int)$userId);
                        })
                    ]