Laravel: create a fake belongsToMany withPivot relationship - php

Question

I have a belongsToMany() relationship between a User and a Group. The user has a level within any group he belongs to.
public function groups()
{
return $this->belongsToMany('App\Group', 'user_group', 'user_id', 'group_id')
->withPivot('level');
}
This works great.
However if the User is an admin, I would like the groups function to return ALL Groups with level = 3, regardless of whether that relationship exists in the pivot table or not.
I can successfully create a Collection which mirrors the data structure as follows:
\App\Group::all()->transform(function ($item, $key) use ($uid) {
$item->pivot = collect(['user_id'=>$uid,'group_id'=>$item->id,'level'=>3]);
return $item;
});
However, I cannot substitute the two outputs as one returns a belongsTo relationship instance and the other returns a Collection. This means I can call ->get() on the former but not the latter.
I thought about using the DB:: facade and creating a Builder for the latter, but I cannot add the Pivot values manually.
Any thoughts on how to achieve this?
-- UPDATE --
I am currently cheating by adding the ->get() inside the groups() method, but this is messy and I would still like to know if there is a better way to solve this problem.
public function groups()
{
if ($this->isAdmin()) {
return \App\Group::all()->transform(function ($item, $key) use ($uid) {
$item->pivot = collect(['user_id'=>$uid,'group_id'=>$item->id,'level'=>3]);
return $item;
});
} else {
return $this->belongsToMany('App\Group', 'user_group', 'user_id', 'group_id')
->withPivot('level')->get();
}
}

Answer 1

So this solution should work(not tested), but it is not the "cleanest" it would be better to access all groups through some other mechanism but because I don't know your admin implemention it is hard to guess.
public function groups()
{
return $this->belongsToMany('App\Group', 'user_group', 'user_id', 'group_id')
->withPivot('level');
}
public function scopeSpecialGroups($query)
{
return $query->when($this->role === 'admin',function($query){
return Group::where('level', '>', 3');
})->when($this->role != 'admin',function($query){
return $query->with('groups');
});
}
Then you should be able to call User::specialGroups()->get();