当数据库多对多时返回一对一关系实例

Question

I have a many to many relationship in the database that looks like User -> user_companies -> company.

My issue is that in terms of our business logic this should be a one to one relationship however correcting this would take a lot of work. In the pivot table there is only ever one entry of a User.

Currently on the user model I am doing this but it returns a model and not a relationship instance.

// returns relationship instance
public function companies()
{
    return $this->belongsToMany('App/Company', 'user_companies');
}

// returns model
public function company()
{
    return $this->companies()->first();
}

Is it possible for me to mimic the behaviour of a one to one relationship whilst the database is set up as many to many?

UPDATE:

Laravel has now added a HasOneThrough relationship out of the box. https://laravel.com/docs/5.8/eloquent-relationships#has-one-through

Answer 1

With this, it's possible but you'd really have to dig into the core and build your own custom solution (Relationship Query Builder).

The first thing that comes to mind is a hasOneThrough relationship method. Unfortunately, this does not exist out of the box. My recommendation is to find a reliable package to accomplish this.

In fact, I was able to find this package: https://github.com/riesjart/relaquent

Otherwise, unless your DB Schema is a complete mess, adding a company_id to your users table and then writing the sql migration script would not be complicated in the least bit. Hope this helps.