問題描述

我有一個帶有 2 個鍵的常規數據透視表.但是，我還有第三列，我想在其中存儲具有一對多關系的不同鍵.這可能嗎?

I have a regular pivot table with 2 keys. However, I also have a 3rd column where I want to store a different key with a one to many relationship. Is this possible to have?

示例:

數據透視表:
組織 1 |組織 2 |關系類型
1 |2 |1
1 |3 |2

Pivot table:
Organization 1 | Organization 2 | Relation type
1 | 2 | 1
1 | 3 | 2

在這種情況下，組織編號 1 與組織編號 2 存在關系，關系類型為編號 1.組織編號 1 也與組織編號 3 存在關系，關系類型為 2.

In this case organization number 1 has a relation with organization number 2 with the relation type being number 1. Organization number 1 also has a relation with organization number 3 with relation type 2.

現在是我的問題，如何在數據透視表上設置額外的一對多關系?

Now is my question, how do I set up that additional one to many relationship on the pivot table?

推薦答案

這里是三元關系.您是說組織 A 與組織 B 和關系類型相關.這是一個非常罕見的用例，因為在絕大多數情況下，三元關系可以簡化為二元關系.您需要對您的數據模型進行非常深入的檢查，以確定您的案例是否可以簡化，但假設不能，這是我的建議.

What you have here is a ternary relationship. You are saying that an organisation A relates with an organisation B and a relationship type. This is a very uncommon use case because in the vast majority of cases ternary relationships can be simplified to binary ones. You need a very deep inspection of your data model to determine whether your case can be simplified, but assuming that it can't here's my suggestions.

值得檢查雄辯的文檔，特別是在為此定義自定義中間表模型.請注意，這需要 Laravel 5.4+ 才能工作.

It's worth checking the eloquent docs in particular under Defining Custom Intermediate Table Models for this. Note that this requires Laravel 5.4+ to work.

以下應該有效:

class OrganisationOrganisationLink extends Pivot {
    public relationType() {
          return $this->belongsTo(RelationType::class); //You need to specify the foreign key correctly as a 2nd parameter
    }
}

然后在您的原始模型中:

Then in your original model:

class Organisation extends Model {
    public relatedOrganisation() {
        return $this->belongsToMany(self::class)->using(OrganisationOrganisationLink::class); 
    }
}

然后在實際使用它時，您可以例如做:

Then when making practical use of this you can e.g. do:

$organisation = Organisation::with('relatedOrganisation')->first();
echo "Got ".$organisation->name." which relates to "
     .$organisation->relatedOrganisation->first()->name 
     ." with relationship type "       
     $organisation->relatedOrganisation->first()->pivot->relationshipType()->value('name'); 

當然，我假設的領域可能不存在，但希望你能明白.

Of course the fields I've assumed may not exist but hopefully you get the idea.

這篇關于Laravel - 數據透視表上的附加關系的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！