Using MyBatis, I am getting close to 65,000 results from a select query within a mapper. I want to create a csv and send these results as a zip file to the UI call which will trigger the download dialog directly of the browser.
Upon searching, I understood that we need to use custom result handler in these scenarios. But the link to the example from ibatis seems to be removed http://code.google.com/p/mybatis/wiki/ResultHandlerExample leaving no accurate steps for me to use or implement it.
However, I have tried as below.
public class CSVExportRowHandler implements ResultHandler {
@SuppressWarnings("unchecked")
@Override
public void handleResult(ResultContext context) {
SRDContainer srdContainer = (SRDContainer) context.getResultObject();
System.out.println("Container: " + srdContainer.toString() + ", " + context.getResultCount() +", "+ context.isStopped());
for (StudentResultDetails srd : srdContainer.getStudentResultDetails()){
System.out.println("result: " + srd.getStudentName());
}
}
}
As the handleResult method must return void. On this note, I have the below queries.
I am able to print to the console only one record upon using this CSVExportRowHandler class. What happened to the rest of the records (should have been 65k) ?
Is there any optimized way of doing this ?
How to trigger the download dialog of browser directly ? before that do I need to write the records to csv or I can stream the results to download ?
Here are my DAO and the jax-rs service for reference
DAO.java
public void exportSRD(HashMap<String, Object> params) {
SqlSession sqlSession = SessionFactory.getSession().openSession();
try {
CSVExportRowHandler handler = new CSVExportRowHandler();
sqlSession.select("getAssignmentSRDSession", params, handler);
} finally {
sqlSession.close();
}
}
Service:
@Path("/{reportType}/studentresultdetails/{function}/{sessionId}")
@GET
public void exportOrPrintUtil(@PathParam("reportType") String reportType, @PathParam("function") String function, @QueryParam("pageNum") Integer pageNum,
@QueryParam("pageSize") Integer pageSize, @QueryParam("sortOn") String sortOn, @QueryParam("sortOrder") String sortOrder,
@QueryParam("filterByName") String filterByName, @PathParam("sessionId") Integer sessionId) throws IOException {
HashMap<String, Object> params = new HashMap<String, Object>();
Object enableSort;
Object enablePrintOrExportFlag;
params.put("sessionId", sessionId);
params.put("enableSort", false);
params.put("enablePrintOrExportFlag", true);
params.put("filterByName", filterByName);
dao.exportSRD(params);
*********** WHAT TO BE RETURNED AS THE ABOVE dao.exportSRD(params) RETURNS VOID. HOW TO TRIGGER DOWNLOAD DIALOG FROM HERE. *****************
}
SRDContainer.java object
@XmlRootElement
public class SRDContainer implements Comparable<SRDContainer> {
private List<StudentResultDetails> studentResultDetails;
public SRDContainer() {}
public SRDContainer(
List<StudentResultDetails> studentResultDetails) {
super();
this.studentResultDetails = studentResultDetails;
}
public List<StudentResultDetails> getStudentResultDetails() {
return studentResultDetails;
}
public void setStudentResultDetails(
List<StudentResultDetails> studentResultDetails) {
this.studentResultDetails = studentResultDetails;
}
@Override
public int compareTo(SRDContainer o) {
return 0;
}
@Override
public String toString() {
return "SRDContainer [studentResultDetails="
+ studentResultDetails + "]";
}
public List<String[]> toStringArrayList() {
String[] array = new String[studentResultDetails.size()];
List<String[]> stringArrayListOut = new ArrayList<String[]>();
int index = 0;
for (StudentResultDetails value : this.studentResultDetails) {
array[index] = value.toFlatCSVString();
index++;
}
stringArrayListOut.add(array);
return stringArrayListOut;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime
* result
+ ((studentResultDetails == null) ? 0 : studentResultDetails
.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
SRDContainer other = (SRDContainer) obj;
if (studentResultDetails == null) {
if (other.studentResultDetails != null)
return false;
} else if (!studentResultDetails.equals(other.studentResultDetails))
return false;
return true;
}
}
I am pretty new to jax-rs and mybatis.
Thanks !!!!
sessionID make your code too complicated , jackoffID as well. even with deferred loading (thanks to CGLib proxies). It gets just a little fuzzy, however, when discussing how to implement complex queries
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