func (c *MyMongoDbPersistence) composeFilter(filter *cdata.FilterParams) bson.M {
	if &filter == nil || filter == nil {
		filter = cdata.NewEmptyFilterParams()
	}

	key := filter.GetAsNullableString("key")
	var filterObj bson.M
	if *key != "" {
		filterObj = bson.M{"key": *key}
	} else {
		filterObj = bson.M{}
	}

	return filterObj
}

func (c *MyMongoDbPersistence) composeSort(sort *cdata.SortParams) bson.M {
	if &sort == nil || sort == nil {
		sort = cdata.NewEmptySortParams()
	}

	sortObj := bson.M{}

	for _, field := range *sort {
		if field.Ascending {
			sortObj[field.Name] = 1
		} else {
			sortObj[field.Name] = -1
		}

	}

	return sortObj
}