查询中的空ResultSet

Question

I'm trying to query for a set and return it as a hash map object with Spring JdbcTemplate. But some reasons I'm getting empty result set from server. It is possible that I have a problem in the overall configuration but the rest of the queries are working without problems.

This is how I query

public Map<Integer, String> getCompanyDataservers() {
    return getTemplate().queryForObject("select id, dataserver from company", new RowMapper<Map<Integer,String>>() {
        @Override
        public Map<Integer, String> mapRow(ResultSet rs, int rowNum)
                throws SQLException {
            HashMap<Integer, String> toReturn = new HashMap<Integer, String>();
            while(rs.next()) {
                int id = rs.getInt("id");
                toReturn.put(id, dataserver);
            }
            return toReturn;
        }});
}

After some debugging and logging statements I concluded that my resultset seems to be empty of any rows. When I query the same ("select id, dataserver from company") manually directly from DB I get the desired result. Yet this way I get a resultset with 0 rows.

One of my theories is that can't get get this kind of set when querying for a object this way. But isn't there a possibility to be free at you queries and construct a more elaborate object as a query result, or I have to create a purpose built class to be used by "queryForList" to get the desired data and convert it afterwards?

Or am I just missing something?

Answer 1

You are not supposed to invoke rs.next() inside mapRow . JdbcTemplate will invoke mapRow for you for every row in the resultset

All you need to do on mapRow is just return a HashMap which represent one single database row , spring will do the resultset iteration for you