Laravel hasManyThrough() returning no results - sql

Question

I have 3 tables and I want to join 2 of them through another using eloquent
ProductGroup table
--------------------------
| ProductGroupId | Name |
-------------------------
| 1 | Test1 |
| 2 | Test2 |
--------------------------
ProductLine table
-------------------------------------------------
| ProductLineId | ProductGroupId | Name |
------------------------------------------------|
| 1 | 1 | AnotherTest1 |
| 2 | 1 | AnotherTest2 |
-------------------------------------------------
ProductType table
----------------------------------------------
| ProductTypeId | ProductLineId | Name |
---------------------------------------------|
| 1 | 1 | Something1 |
| 2 | 1 | Something2 |
----------------------------------------------
I want to join ProductGroup with ProductType
I tried using this as my ProductGroup model (not sure if I've done the hasManyThrough() correctly)
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class ProductGroup extends Model
{
protected $primaryKey = 'ProductGroupId';
public $timestamps = false;
public function producttype()
{
return $this->hasManyThrough('App\ProductGroup', 'App\ProductLine', 'ProductGroupId', 'ProductGroupId');
}
}
I want to join the 2 tables on a particular id from the ProductGroup table so really in SQL it would be
SELECT * FROM ProductType pt
INNER JOIN ProductLine pl ON
pt.ProductLineId = pl.ProductLineId
INNER JOIN ProductGroup pg ON
pg.ProductGroupId = pl.ProductGroupId
WHERE pg.ProductGroupId = 3
I have tried this but I get no results
I could do this in query builder but i'd rather use eloquent if it can be helped
$test = ProductGroup::with('producttype')->whereHas('producttype', function ($query) {
$query->where('ProductGroup.ProductGroupId', 3);
})->get();

Answer 1

Change
public function producttype()
{
return $this->hasManyThrough('App\ProductGroup', 'App\ProductLine',
'ProductGroupId', 'ProductGroupId');
}
to
public function producttype()
{
return $this->hasManyThrough('App\ProductType', 'App\ProductLine', 'ProductGroupId', 'ProductLineId');
}