Querygen.php

    public function generateRelationsQuery($request, $db_query, $model, $filter_relations)
    {
        $filter_appends = [];

        foreach ($filter_relations as $key => $value) {
            if (!isset($value['custom_query'])) {
                if ($request->has('filter-remote-' . strtolower($key))) {
                    $select_value = $request->input('filter-remote-' . strtolower($key));
                    if (!empty($select_value)) {
                        $filter_appends['filter-remote-' . strtolower($key)] = $select_value;

                        if (false != strpos($value['field'], '.')) {
                            $splitted_filter_values = explode(',', $select_value);

                            $values = explode('.', $value['field']);

                            $db_query->whereHas($values[0], function ($db_query) use ($model, $values, $splitted_filter_values) {
                                $db_query->where(function ($db_query) use ($model, $values, $splitted_filter_values) {
                                    $db_query->whereIntegerInRaw($values[1], $splitted_filter_values);
                                });
                            });
                        } else {
                            $db_query->whereIntegerInRaw($model . '.' . $value['field'], explode(',', $select_value));
                        }
                    }
                }
            }
        }

        return $filter_appends;
    }