public function storeFilters(?array $selected_filters = []): self 	{ 		$selected_filters ??= [];  		$stored_filters = $this->categoryFilters->pluck('filter_id')->all(); 		// delete all deselected 		$difference = array_diff($stored_filters, $selected_filters); 		$category_filters = $this->categoryFilters()->whereIn('filter_id', $difference)->get();  		foreach ($category_filters as $cf) { 			$cf->delete(); 		}  		// create new if needed 		$selected_filters = array_diff($selected_filters, $stored_filters);  		foreach ($selected_filters as $filter) { 			$this->categoryFilters()->firstOrCreate([ 				'filter_id' => $filter, 			]); 		}  		return $this; 	}