I am new to spring batch and I wanted to get some guidance please around a issue I am experiencing. I have two db tables Settlement_Header ( which has the header info of the file) and Settlement_Detail( which is a list of all the transactions for that header file.)
The goal is to create a file that has 1 header and multiple details.
Current Output - The header appears on each record and I want it to appear once. I tried to include a condition in the Item Processor but it did not resolve my issue.
Desired Output
This is my Itemreader
@Bean(destroyMethod="")
public JdbcCursorItemReader<Settlement> settlementreader(){
JdbcCursorItemReader<Settlement> ItemReader = new JdbcCursorItemReader<>();
ItemReader.setDataSource(dataSource);
ItemReader.setSql("SELECT DISTINCT A.PROCESS_DATE,A.FILE_NAME,A.SERVICE,A.SUB_SERVICE,A.SENDER,A.RUN_MODE,A.CURRENCY,A.PROCESS_WINDOW_NO,B.RECORD_SEQ_NO,"
+ "B.AGENT_FROM,B.AGENT_TO,B.SETTLE_VOLUME,B.AMOUNT_CURRENCY,B.SETTLE_AMOUNT "
+ "FROM SETTLEMENT_HEADER A,SETTLEMENT_DETAIL B WHERE A.FILE_ID=B.FILE_ID");
ItemReader.setRowMapper(new SettlementRowMapper());
return ItemReader;
}
Writer
@Bean (destroyMethod="")
public StaxEventItemWriter<Settlement> settlementwriter() throws Exception {
StaxEventItemWriter<Settlement> ItemWriter = new StaxEventItemWriter<>();
ItemWriter.setResource(new FileSystemResource(".../Settlement.xml"));
ItemWriter.setRootTagName("Settlement");
ItemWriter.setMarshaller(marshaller);
ItemWriter.afterPropertiesSet();
return ItemWriter;
}
Row Mapper
public class SettlementRowMapper implements RowMapper {
@Override
public Settlement mapRow(ResultSet rs, int rowNum) throws SQLException {
Settlement Settlement = new Settlement ();
List<SettlementHeader> settlementheader= new ArrayList<SettlementHeader>();
List<SettlementDetail> settlementdetail = new ArrayList<SettlementDetail>();
SettlementHeader header = new SettlementHeader();
SettlementDetail detail = new SettlementDetail();
SttlAmt sttlAmt = new SttlAmt();
header.setPrcDte(rs.getDate("PROCESS_DATE").toLocalDate());
header.setFilename(rs.getString("FILE_NAME"));
header.setService(rs.getString("SERVICE"));
header.setSubServ(rs.getString("SUB_SERVICE"));
header.setSender(rs.getInt("SENDER"));
header.setRunMode(rs.getString("RUN_MODE"));
header.setCurrency(rs.getString("CURRENCY"));
header.setPrcWndwNum(rs.getInt("PROCESS_WINDOW_NO"));
detail.setSeqNumb(rs.getInt("RECORD_SEQ_NO"));
detail.setAgntFrm(rs.getInt("AGENT_FROM"));
detail.setAgntTo(rs.getInt("AGENT_TO"));
detail.setSttlVol(rs.getInt("SETTLE_VOLUME"));
sttlAmt.setCcy(rs.getString("AMOUNT_CURRENCY"));
sttlAmt.setValue(rs.getDouble("SETTLE_AMOUNT"));
detail.setSttlAmt(sttlAmt);
settlementheader.add(header);
settlementdetail.add(detail);
Settlement.setSettlementDetails(settlementdetail);
Settlement.setSettlementHeader(settlementheader);
return Settlement;
}
The behavior you are having is absolutely normal, since for each Item you read you have a Settlement object that contains one Header and one Detail.
Your problem is a common one in the batch processing realm and with Spring Batch it is called "Driving Query Based ItemReaders", you can find more about that in here.
The way I would approach your problem following this pattern is by creating a reader that only returns SettlementHeader Items, and add a processor that takes each Item (SettlementHeader) and transforms it into a Settlement Object by querying the database for the Settlement Details.
Here is my solution:
Step Items
@Bean(destroyMethod = "")
public JdbcCursorItemReader<SettlementHeader> settlementHeaderReader(DataSource dataSource) {
JdbcCursorItemReader<SettlementHeader> ItemReader = new JdbcCursorItemReader<>();
ItemReader.setDataSource(dataSource);
ItemReader.setSql("SELECT DISTINCT A.FILE_ID, A.PROCESS_DATE, A.FILE_NAME, A.SERVICE, A.SUB_SERVICE, A.SENDER, A.RUN_MODE, A.CURRENCY, A.PROCESS_WINDOW_NO"
+ "FROM SETTLEMENT_HEADER A");
ItemReader.setRowMapper(new SettlementHeaderRowMapper());
return ItemReader;
}
@Bean
public ItemProcessor<SettlementHeader, Settlement> settlementHeaderProcessor(JdbcTemplate jdbcTemplate){
return item -> {
List<SettlementDetail> settlementDetails = jdbcTemplate.query("SELECT B.RECORD_SEQ_NO, B.AGENT_FROM,B.AGENT_TO,B.SETTLE_VOLUME,B.AMOUNT_CURRENCY,B.SETTLE_AMOUNT " +
" FROM SETTLEMENT_DETAIL B WHERE ? = B.FILE_ID",
new Object[]{item.getFileId()},
new SettlementDetailRowMapper());
Settlement settlement = new Settlement ();
List<SettlementHeader> settlementheader= new ArrayList<SettlementHeader>();
settlementheader.add(item);
settlement.setSettlementDetails(settlementDetails);
settlement.setSettlementHeader(settlementheader);
return settlement;
};
}
// Your writer should stay the same
@Bean(destroyMethod = "")
public StaxEventItemWriter<Settlement> settlementwriter() throws Exception {
StaxEventItemWriter<Settlement> ItemWriter = new StaxEventItemWriter<>();
ItemWriter.setResource(new FileSystemResource(".../Settlement.xml"));
ItemWriter.setRootTagName("Settlement");
ItemWriter.setMarshaller(marshaller);
ItemWriter.afterPropertiesSet();
return ItemWriter;
}
Row Mappers
public class SettlementHeaderRowMapper implements RowMapper<SettlementHeader> {
@Override
public SettlementHeader mapRow(ResultSet rs, int i) throws SQLException {
SettlementHeader header = new SettlementHeader();
header.setFileId(rs.getInt("FILE_ID"));
header.setPrcDte(rs.getDate("PROCESS_DATE").toLocalDate());
header.setFilename(rs.getString("FILE_NAME"));
header.setService(rs.getString("SERVICE"));
header.setSubServ(rs.getString("SUB_SERVICE"));
header.setSender(rs.getInt("SENDER"));
header.setRunMode(rs.getString("RUN_MODE"));
header.setCurrency(rs.getString("CURRENCY"));
header.setPrcWndwNum(rs.getInt("PROCESS_WINDOW_NO"));
return header;
}
}
public class SettlementDetailRowMapper implements RowMapper<SettlementDetail> {
@Override
public SettlementDetail mapRow(ResultSet rs, int i) throws SQLException {
SettlementDetail detail = new SettlementDetail();
SttlAmt sttlAmt = new SttlAmt();
detail.setSeqNumb(rs.getInt("RECORD_SEQ_NO"));
detail.setAgntFrm(rs.getInt("AGENT_FROM"));
detail.setAgntTo(rs.getInt("AGENT_TO"));
detail.setSttlVol(rs.getInt("SETTLE_VOLUME"));
sttlAmt.setCcy(rs.getString("AMOUNT_CURRENCY"));
sttlAmt.setValue(rs.getDouble("SETTLE_AMOUNT"));
detail.setSttlAmt(sttlAmt);
return detail;
}
}
I hope this helps you.