Question

我正在构建一个博客应用程序，我有

Post，City，Neighbourhood，SubNeighbourhood。

我到目前为止的关系介于City，Neighbourhood和subNeighbourhood之间，如下所示：

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。帖子表包含id_city，id_neighbourhood和id_subNeighbourhood。

我的问题是：

如果帖子结构正确吗？我觉得有很多“id _...”不行。

第二个问题是如何在帖子中写下关系？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');

所以帖子属于Subneighbourhood，属于属于城市的邻居

Answer 2

我认为多态关系将是解决问题的好方法。（我没有测试我的代码，也没有测试过什么）

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：

示例，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

示例如果我们有一个与邻居相关的帖子

$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

您可以使用

轻松安全发布

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

or 

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

Laravel与多个模型的关系

2 个答案: