Laravel 5.4 字段没有默认值

我遇到了这个错误，我检查过的谷歌搜索结果都与我的问题不相似.

I am having this error and none of the 谷歌d result i checked is similar to my problem.

我有一个包含 Deal、User 和 Matches 类的应用程序

I have an application with class Deal, User, and Matches

一笔交易有很多匹配项.一个用户有很多匹配.一个用户有很多交易.

A deal has many matches. A user has many matches. A user has many deals.

我正在尝试使用我的 Deal 对象创建一个新的匹配

I am attempting to create a new Match using my Deal object

$deal->matches()->create(['user_id'=>$id]);

这是我的匹配类，我已经定义了所有需要的关系

This is my match class, i have defined all needed relationships

class Match extends Model
{
    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $guarded = [];
    public $timestamps = false;
    public $expired_on = "";


    public static function boot()
    {
        parent::boot();

        static::creating(function ($model) {
            $model->matched_on = $model->freshTimestamp();
        });
    }

    public function __construct(){
        $d = (new DateTime($this->matched_on))->modify(' 1 day');
        $this->expired_on = $d->format('Y-m-d H:i:s');
    }


    /**
     * Get the user that owns the match.
     */
    public function user()
    {
        return $this->belongsTo('AppUser');
    }

    /**
     * Get the deal that owns the match.
     */
    public function deal()
    {
        return $this->belongsTo('AppDeal');
    }
}

当我尝试创建新匹配项时，我不断收到此错误.

And i keep getting this error when i attempt to create a new match.

Connection.php 第 647 行中的 QueryException:SQLSTATE[HY000]:一般错误:1364 字段user_id"没有默认值(SQL:插入matches(deal_id)值(1))

QueryException in Connection.php line 647: SQLSTATE[HY000]: General error: 1364 Field 'user_id' doesn't have a default value (SQL: insert into matches (deal_id) values (1))

我的守卫是一个空数组，可能是什么问题?

I have my guarded to be an empty array, what could be the problem?