Laravel 中与数据透视表的多态关系？
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Polymorphic relationships with pivot table in Laravel?
提问by Andreas Franzén
I got 3 models, Article, Building, Person.
我有 3 个模型，文章、建筑、人物。
These models need to reference each other in a few ways. For example the building needs to be able to reference collections of Person like $building->architects(), $building->owners(), a article might reference collections of Person with $article->authors() and Person might reference collections of Building like $person->owned_buildings()
Each model should have a function like "references" to get a collection of mixed models.
这些模型需要以几种方式相互引用。例如，建筑物需要能够引用像 $building->architects()、$building->owners() 这样的 Person 集合，一篇文章可能会通过 $article->authors() 引用 Person 的集合，而 Person 可能会引用集合像 $person->owned_buildings() 这样的建筑
每个模型都应该有一个类似于“引用”的函数来获取混合模型的集合。
I'm thinking that this should be possible with something like:
我认为这应该可以通过以下方式实现：
class Article extends Eloquent {
public function referenceable()
{
return $this->morphTo();
}
public function authors()
{
return $this->morphMany('Person', 'referenceable');
}
}
class Building extends Eloquent {
public function referenceable()
{
return $this->morphTo();
}
public function architects()
{
return $this->morphMany('Person', 'referenceable');
}
}
class Person extends Eloquent {
public function referenceable()
{
return $this->morphTo();
}
public function owned_buildings()
{
return $this->morphMany('Building', 'referenceable');
}
}
So the question is what would the pivot table look like?
所以问题是数据透视表会是什么样子？
回答by BigBlueHat
You can define a belongsTousing a morphMany-stylerelationship by adding a whereto the mix:
您可以通过在混合中添加 a来定义belongsTo使用morphMany-style关系where：
public function followers() {
return $this
->belongsToMany('User', 'follows', 'followable_id', 'user_id')
->where('followable_type', '=', 'Thing');
}
The wherewill simply be sure Eloquent doesn't mismatch IDs.
这where将只是确保 Eloquent 不会与 ID 不匹配。
Hope that helps!
希望有帮助！
回答by BenG
Polymorphic relationships are basically 1-to-many relationships. They allow you to reuse a model on many other models.
多态关系基本上是一对多的关系。它们允许您在许多其他模型上重用模型。
For instance if Post has many images, and a User might have many avatars, you can use the same image models without conflict. So instead of setting an image with a user_id field and a post_id field, you can use a generic imageable_id.
例如，如果 Post 有很多图像，而一个 User 可能有很多头像，那么您可以使用相同的图像模型而不会发生冲突。因此，您可以使用通用的 imageable_id，而不是使用 user_id 字段和 post_id 字段设置图像。
You require a many-to-many relationship which is not currently supported with Eloquent's morphMany()
Eloquent 的 morphMany() 当前不支持多对多关系
You can do several types of pivot tables for that. For instance set up two architect/building and owner /building pivot tables separately with building_id and person_id fields. Or you could setup a single pivot table with an extra 'type' field to define the role
您可以为此执行多种类型的数据透视表。例如，分别使用 building_id 和 person_id 字段设置两个建筑师/建筑和所有者/建筑数据透视表。或者您可以设置一个带有额外“类型”字段的数据透视表来定义角色
