Laravel Complex Relationships Through Polymorphism - laravel

Question

I have the following models using Laravel 5.3:
Provider:
// Provider model
$primaryKey = 'id'
public function activities()
{
return $this->hasMany(Activity::class);
}
Activity:
// Activity model
$primaryKey = 'id'
public function provider()
{
return $this-belongsTo(Provider::class);
}
public function semesters()
{
return $this->hasMany(Semester::class);
}
public function semesterPurchases()
{
return $this->hasManyThrough(Purchase::class, Semester::class, 'activity_id', 'purchasable_id')
->where('purchasable_type', Semester::class);
}
Semester:
// Semester model
$primaryKey = 'id'
public function activity()
{
return $this->belongsTo(\App\Models\Activity::class, 'activity_id', 'id');
}
Purchase:
// Purchase model
$primaryKey = 'id'
public function purchasable()
{
return $this->morphTo();
}
In my case Semester::class is the purchasable_type. Is there a way to establish a relationship between Provider::class and Purchase::class? In order to make it possible to do something like this:
$providers = Provider::select('id', 'name', 'address')
->with('purchases')
->where('providers.id', 1)
->get();
I would prefer not to go through activities like so:
$providers = Provider::select('id', 'name', 'address')
->with('activities.purchases')
->where('providers.id', 1)
->get();
which I know I can do using hasManyThrough on the Activity::class

Answer 1

Laravel has no native support for a direct relationship.
I've created a package for cases like this: https://github.com/staudenmeir/eloquent-has-many-deep
class Provider extends Model
{
use \Staudenmeir\EloquentHasManyDeep\HasRelationships;
public function purchases()
{
return $this->hasManyDeep(
Purchase::class,
[Activity::class, Semester::class],
[null, null, ['purchasable_type', 'purchasable_id']]
);
}
}
Provider::find($id)->purchases;