有多個型號

Question

我建立一個博客應用程序，我有

Post，City，Neighbourhood，SubNeighbourhood Laravel關係。

，我直到現在的關係之間City，Neighbourhood和subNeighbourhood喜歡如下：

subNeighbourhood belongs to Neighbourhood 
Neighbourhood belongs to city 

第二個關係是像

City hasMany Neighbourhoods 
Neighbourhood hasMany subNeighbourhoods 

當我創建的帖子我的問題。帖子表格有id_city,id_neighbourhood和id_subNeighbourhood。

我有的問題是：

如果帖子結構是正確的？我覺得有很多「ID _...」不好。

第二個問題是我如何在帖子中寫關係？所有列「id _...」都有外鍵到每個對應的表。

Answer 1

爲了什麼我可以從你的解釋理解後的表應該只有一個subneighbourhood_id場，在Post類的關係應該是：

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

因此，一個專屬於那個屬於附近一個Subneighbourhood屬於一個城市

Answer 2

我認爲多態關係將是一個很好的解決您的問題。 （我沒測試我的代碼或什麼那麼）

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：

例如，如果我們具有的選擇關係到一個城市

$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 

實例後，如果我們具有的選擇與鄰近的後

$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 

您可以安全方便地後用

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

or 

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