Hi,
I have created 3 classes as follow:
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Department {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;
@Persistent
private String deptName;
// Getters and setters
}
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Person {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;
@Persistent
private String firstName;
@Persistent
private String lastName;
@Persistent
private Department department;
@Persistent(mappedBy = "employee")
private List<MonthlySalary> monthlySalaryList;
// Getters and setters
}
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class MonthlySalary {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;
@Persistent
private Date salaryDate;
@Persistent
private double amount;
@Persistent
private Person employee;
// Getters and setters
}
Now, I have used JDO to store these objects in following way:
Department department = null;
PersistenceManager pm = PMF.get().getPersistenceManager();
Person employee = null;
try {
// ///////////////////////////// Employee
KeyFactory.Builder keyBuilder = new KeyFactory.Builder
(Department.class.getSimpleName(), "D11");
department = new Department();
department.setKey(keyBuilder.getKey());
department.setDeptName("ennovate");
keyBuilder = new
KeyFactory.Builder(Person.class.getSimpleName(),
"E01");
employee = new Person();
employee.setKey(keyBuilder.getKey());
employee.setFirstName("Chetan");
employee.setLastName("Soni");
employee.setDepartment(department);
pm.makePersistent(employee);
}
catch (Exception e) {
e.printStackTrace();
}
finally {
pm.close();
}
pm = PMF.get().getPersistenceManager();
try {
// ///////////////////////////// Monthly Salary 1
KeyFactory.Builder keyBuilder = new KeyFactory.Builder
(Person.class.getSimpleName(), "E01");
keyBuilder.addChild(MonthlySalary.class.getSimpleName(), "M01");
MonthlySalary monthlySalary = new MonthlySalary();
monthlySalary.setKey(keyBuilder.getKey());
monthlySalary.setAmount(50000);
monthlySalary.setEmployee(pm.getObjectById(Person.class, "E01"));
monthlySalary.setSalaryDate(new Date());
pm.makePersistent(monthlySalary);
}
catch (Exception e) {
e.printStackTrace();
}
finally {
pm.close();
}
pm = PMF.get().getPersistenceManager();
try {
// ///////////////////////////// Monthly Salary 2
KeyFactory.Builder keyBuilder = new KeyFactory.Builder
(Person.class.getSimpleName(), "E01");
keyBuilder.addChild(MonthlySalary.class.getSimpleName(), "M02");
MonthlySalary monthlySalary = new MonthlySalary();
monthlySalary.setKey(keyBuilder.getKey());
monthlySalary.setAmount(60000);
monthlySalary.setEmployee(pm.getObjectById(Person.class, "E01"));
monthlySalary.setSalaryDate(new Date());
pm.makePersistent(monthlySalary);
}
catch (Exception e) {
e.printStackTrace();
}
finally {
pm.close();
}
Now When I access MonthlySalary using:
String query1 = "select from " + MonthlySalary.class.getName();
List<MonthlySalary> alist = (List<MonthlySalary>) pm.newQuery
(query1).execute();
for(MonthlySalary monthlySalary : alist) { // Giving error at this
line
System.out.println(monthlySalary.getEmployee().getFirstName());
}
It's giving me the error:
org.datanucleus.exceptions.NucleusUserException: Field
org.example.wa.MonthlySalary.employee should be able to provide a
reference to its parent but the entity does not have a parent. Did
you perhaps try to establish an instance of
org.example.wa.MonthlySalary as the child of an instance of
org.example.wa.Person after the child had already been persisted?
Can anyone please suggest what's wrong with this program?
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