Laravel雄辩的拯救行为

Question

在保存hasMany关系之前，Laravel要求您保存父模型是否正常？我可以在保存模型之前使用belongsTo。

    $team = new Team();
    $team->tournament()->associate($tournament);
    // $team->save(); without this line, it will throw an error

    $team->players()->save(new TeamPlayer([
        'user_id' => 1
    ]));
    $team->save();

团队模型的关系如下所示：

public function players()
{
    return $this->hasMany(TeamPlayer::class);
}

public function tournament()
{
    return $this->belongsTo(Tournament::class);
}

抛出的错误是这个

Integrity constraint violation: 1048 Column 'team_id' cannot be null (SQL: insert into `team_players` (`user_id`, `team_id`, `updated_at`, `created_at`) values (1, , 2017-12-18 13:32:29, 2017-12-18 13:32:29))