I have ProductCollection Model and AttributeValue Model which have a common table product_collection_attributes that has 2 columns: product_collection_id and attribute_value_id that are a foreign key to their respective tables and are both a primary key.

In ProductCollection Model relation is:

public function attributes()
{
  return $this->belongsToMany(AttributeValue::class, 'product_collection_attributes', 'product_collection_id');
}

And in AttributeValue Model relation is:

public function product_collections()
{
  return $this->belongsToMany(ProductCollection::class, 'product_collection_attributes', 'attribute_value_id');
}

My query is: $productCollection->attributes()->get(); which is returning an empty array,
However if query was DB::table('product_collection_attributes')->where('product_collection_id', $productCollection->id)->get(); its returning a full array!!

I don’t know why and it is important to use ProductCollection::with(['attributes']) in almost all of my cases specially with joins, and it is forcing me to use DB instead!

How can we fix that?