Laravel与多个模型的关系

Question

我正在构建一个博客应用程序

Post ， City ， Neighbourhood ， SubNeighbourhood 。

我到现在为止的关系是City ， Neighbourhood和subNeighbourhood Neighbourhood之间的关系如下：

subNeighbourhood belongs to Neighbourhood 
Neighbourhood belongs to city

第二种关系就像

City hasMany Neighbourhoods 
Neighbourhood hasMany subNeighbourhoods 

我的问题是我创建帖子的时候。 帖子表有id_city ， id_neighbourhood和id_subNeighbourhood 。

我的问题是：

如果帖子结构是正确的？ 我觉得有很多“id _...”不行。

第二个问题是如何在帖子中写出关系？ 所有列“id _...”都有每个对应表的外键。

Answer 1

对于我从你的解释中可以理解的内容，post表应该只有一个subneighbourhood_id字段，在Post类中，关系应该是：

public function subneighbourhood()
{
    return $this->belongsTo('App\Subneighbourhood');

因此，帖子属于属于属于城市的社区的Subneighbourhood

Answer 2

我认为多态关系将是解决问题的一个很好的解决方案。 （我没有测试我的代码或者有什么问题）

class Post extends Model
{
   // Can return a City or Neighbourhood or SubNeighbourhood
   public function related() {
      return $this->morphTo();
   }
}

class City extends Model 
{
   public function posts() {
      return $this->morphMany(App\Models\Post::class, 'related');
   }
} 


class Neighbourhood extends Model 
{
   public function posts() {
      return $this->morphMany(App\Models\Post::class, 'related');
   }
} 

如何使用这个：

例如，如果我们有一个与城市相关的帖子

$post = Post::find(1);
$true = ($post->related instanceof City);  // This will be true if post related to a city
$neightbourhoods = $post->related->neightbourhoods(); // All the neightbourhoods of the city

例如，如果我们有一个与社区相关的帖子

$post = Post::find(2);
$true = ($post->related instanceof Neighbourhood); // This will be true if post is related to a neighbourhood
//In this case we can do
$post->neighbourhood->subNeighbourhoods(); // All the sub neighbourhoods

您可以轻松安全地发布

$post = new Post();
$post->related = City::find(1); 
$post->save();

or 

$post = new Post();
$post->related = Neighbourhood::find(1);
$post->save();