使用对象过滤查询集

Question

目前我有

foreach($this->friends as $friend) {
    $user_ids[] = $friend->id;
}

$posts = Post::whereIn("user_id", $user_ids)->orderBy("date_published", "desc")->paginate(15);

似乎还可以，但是数组的创建有点奇怪。有没有办法可以通过User对象自己进行过滤？例如

Post::whereIn("user", $this->friends)

其中$this->friends将是

public function friends() {
    return $this->belongsToMany("App\User", "friends_users", "user_id", "friend_id");
}

Answer 1

$this->friends是一个Collection对象，它有lists方法，可以从列创建数组，或者从2列创建关联数组。这是你如何使用它。

$posts = Post::whereIn("user_id", $this->friends->lists('id'))->orderBy("date_published", "desc")->paginate(15);