How to convert jdbc template query result to JSON Array in java? - sql-server

Question

I am converting software from Delphi to Spring boot. I have lots of queries in an existing SQL Server database, and I want to display them.
For every query, I have to create entity class, that override row mapper and create entity class.
public class PregledTroskova {
int RbrStavke;
int RbrNaloga;
String Konto;
String SifKomint;
float Duguje;
float Potrazuje;
public PregledTroskova() {
}
public int getRbrStavke() {
return RbrStavke;
}
public void setRbrStavke(int rbrStavke) {
RbrStavke = rbrStavke;
}
public int getRbrNaloga() {
return RbrNaloga;
}
public void setRbrNaloga(int rbrNaloga) {
RbrNaloga = rbrNaloga;
}
public String getKonto() {
return Konto;
}
public void setKonto(String konto) {
Konto = konto;
}
public String getSifKomint() {
return SifKomint;
}
public void setSifKomint(String sifKomint) {
SifKomint = sifKomint;
}
public float getDuguje() {
return Duguje;
}
public void setDuguje(float duguje) {
Duguje = duguje;
}
public float getPotrazuje() {
return Potrazuje;
}
public void setPotrazuje(float potrazuje) {
Potrazuje = potrazuje;
}
}
Then after that I have to write one more class for mapper
class PregledTroskovaRowMapper implements RowMapper<PregledTroskova> {
#Override
public PregledTroskova mapRow(ResultSet resultSet, int i) throws SQLException {
PregledTroskova pregledTroskova = new PregledTroskova();
pregledTroskova.setDuguje(resultSet.getFloat("Duguje"));
pregledTroskova.setPotrazuje(resultSet.getFloat("Potrazuje"));
pregledTroskova.setRbrStavke(resultSet.getInt("RbrStavke"));
pregledTroskova.setRbrNaloga(resultSet.getInt("RbrNaloga"));
pregledTroskova.setKonto(resultSet.getString("Konto"));
pregledTroskova.setSifKomint(resultSet.getString("SifKomint"));
return pregledTroskova;
}
}
Is there any way to just generate json list/array of object where property is result set name value for all rows from select?

Answer 1

If you don't want to create an entity class for every query, you can return a List<Map<String, Object>> which is a list of all rows, each row is represented by a Map (column / value).
Example :
final List<Map<String, Object>> rows = jdbcTemplate.queryForList(yourQuery);
for (final Map<String, Object> row : rows) {
// do something like : row.get("yourField");
}

Answer 2

Example :
String sql = "select * from mytable";
result= jdbcTemplate.query(sql, new AnyObjectMapper());
Mapper (generic) :
class AnyObjectMapper implements RowMapper<Map<String, Object>> {
public AnyObjectMapper() {
// TODO Auto-generated constructor stub
}
#Override
public Map<String, Object> mapRow(ResultSet rs, int rowNum) throws SQLException {
ResultSetMetaData rsMeta = rs.getMetaData();
int colCount = rsMeta.getColumnCount();
Map<String, Object> columns = new HashMap<String, Object>();
for (int i = 1; i <= colCount; i++) {
columns.put(rsMeta.getColumnLabel(i), rs.getObject(i));
}
return columns;
}
}