Why in new Transaction I couldn't read inner entity? - spring

Question

I would like to open a new transaction and use all the changes which I have made in first transaction. But from second transaction I couldn't read inner Entity
class A {
#Autowirde
private B b;
#Transactional
public test() {
ProgramRole programRole = new ProgramRole();
programRoleRepo.save(programRole);
Program program = new Program();
program.setProgramRole(programRole);
programRepo.save(program); // Let say id is 1
Program p = programRepo.getOne(1);
p.getProgramRole() // Return 'programRole'
b.test();
}
}
#Component
class B {
#Transactional(propagation = Propagation.REQUIRES_NEW, isolation = Isolation.READ_UNCOMMITTED)
public void test() {
Program p = programRepo.getOne(1);
p.getProgramRole() // Return null. Why?
}
}

Answer 1

Hibernate holds the persistable state in memory, The process of synchronizing this state to the underlying DB is called flushing. When we use the save() method, the data associated with the save operation will not be flushed to the DB unless and until an explicit call to flush() or commit() method is made, In your case Transactional annotation will do that
as b.test method is calling from with in a transaction so your are getting null there as first transaction still in process(transaction will commit data when method execution competed).
For your use case, you need to use saveAndFlush instead of only save
ProgramRole programRole = new ProgramRole();
programRoleRepo.saveAndFlush(programRole);
Program program = new Program();
program.setProgramRole(programRole);
programRepo.saveAndFlush(program); /