MySql insert data in wrong order from JPA - mysql

Question

I am trying to import the data from excel ile to different tables in my DB.
The import is done , the only problem is that some of the data is in the wrong order.
This is what my excel file loks like.
And this is what the data in my Bd lokks like.
My service file has this method:
#Override
public List<Task> getTasksFromExcel(MultipartFile files) throws IOException {
List<Task> taskList = new ArrayList<>();
XSSFWorkbook workbook = new XSSFWorkbook(files.getInputStream());
XSSFSheet worksheet = workbook.getSheetAt(0);
String a = "A";
for (int index = 0; index <= worksheet.getPhysicalNumberOfRows(); index++) {
if (index > 1) {
Task task = new Task();
Lot lot = new Lot();
String ref = a + index;
CellReference cr = new CellReference(ref);
XSSFRow row = worksheet.getRow(cr.getRow());
String lotName = row.getCell(0).getStringCellValue();
Lot existingLot = lotRepository.findByName(lotName);
if (existingLot == null) {
lot.setName(lotName);
lotRepository.save(lot);
} else {
lot = existingLot;
}
;
task.setName(row.getCell(1).getStringCellValue());
String email = row.getCell(2).getStringCellValue();
Collaborator collab = collaboratorRepository.findByEmail(email);
task.setCollaborator(collab);
List<Double> iC = new ArrayList<>();
for (int i = 3; i < 6; i++) {
iC.add((Double) row.getCell(i).getNumericCellValue());
}
Set<Double> charge = new HashSet<Double>();
charge.addAll(iC);
task.setInitialCharge(charge);
task.setLot(lot);
taskList.add(task);
taskRepository.save(task);
}
}
return taskList;
}
And for the entity definition I go tthis.
#Entity
#Table(name = "task")
public class Task {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String name;
private String description;
private Date assignment;
private Date deadline;
#ElementCollection
private Set<Double> initialCharge=new HashSet<Double>();
#Column(columnDefinition = "varchar(32)")
#Enumerated(EnumType.STRING)
private Status status = Status.TODO;
#ManyToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "lot_id")
private Lot lot;
#ManyToOne()
#JoinColumn(name = "collaborator_id")
private Collaborator collaborator;

Answer 1

You mapped this differently then your excel spreadsheet, and so lose the S1,S2,S3 column name/ordering you had for the single Task row, and seemed to have assumed that the set positional would be consistent, giving you S1-S3 for free. It does not.
Normalizing this out to allow expanding lists of charges and still having an order would mean adding a positional column to the task_initial_charges table. JPA will populate this column behind the scenes if you simply annotate your element collection with the OrderColumn to specify it:
The task_initial_charge needs s1,s2,s3 columns so that a single task_id has 3 positional columns, or you need another column in there to allow writing out the position within your initialCharge Set.
#ElementCollection
#OrderColumn
private Set<Double> initialCharge=new HashSet<Double>();
The order of the initialCharge set when the entity is persisted will then be stored in the database, and should be used when fetching the entity.