Build the DSL query for counting the number of items.

        :param date_field: field with the date
        :param start: date from which to start counting, should be a datetime.datetime object
        :param end: date until which to count items, should be a datetime.datetime object
        :param filters: dict with the filters to be applied
        :return: a DSL query with size parameter

def get_count(cls, date_field=None, start=None, end=None, filters={}):
        """
        Build the DSL query for counting the number of items.

        :param date_field: field with the date
        :param start: date from which to start counting, should be a datetime.datetime object
        :param end: date until which to count items, should be a datetime.datetime object
        :param filters: dict with the filters to be applied
        :return: a DSL query with size parameter
        """
        """ Total number of items """
        query_basic = cls.__get_query_basic(date_field=date_field,
                                            start=start, end=end,
                                            filters=filters)
        # size=0 gives only the count and not the hits
        query = query_basic.extra(size=0)
        return query