Spring JPA delete entity not working when iterating-CodePudding

Hi I am trying to delete an entity using its remove method of its repository from another service class, but it is not getting deleted. Below code works when I hard code the Id,

long id = 1234;
Optional<Employee> employeeOptional = employeeRepository.findById(id);
Employee employee = employeeOptional.get();
employeeRepository.delete(employee);

Above code is working fine, but if I try with below code, deletion is not happening.

for (Employee employee : department.getEmployees()) {
     if (employee.getRole().equals("Manager")) {
        employeeRepository.delete(employee);
     }
}

I am trying the code from DepartmentServiceImpl class, but above is not working, but same when id is hardcoded it works.

Inside Department I have relationship like below,

  @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, mappedBy = "deal")
  private Set<Employee> employees= new HashSet<>();

And inside Employee I have like below,

  @ManyToOne
  @JoinColumn(name = "department_id", referencedColumnName = "department_id")
  private Department department;

Please let me know if anyone has faced this issue. Thanks in advance.

CodePudding user response：

You are attempting to delete Employees, but your entities still have references to each other.

A better way to delete an employee is to use orphan removal and remove the employee from the collection which will trigger a delete.

Also mappedBy = "deal" should be the name of the attribute on the owning side of the relationship so this should be mappedBy = "department"

@OneToMany(
    cascade = CascadeType.ALL,
    mappedBy = "department",
    orphanRemoval = true
)
private Set<Employee> employees= new HashSet<>();

add a method to Department to remove the Employee and keep the bidirectional relationship in sync by also removing Department from Employee

public void removeEmployee(Employee employee) {
    employees.removeEmployee(employee);
    employee.setDepartment(null);
}

you can then remove the 'Managers' from your Employees collection which should trigger the delete statements

List<Employee> managers = department.getEmployees.stream()
                .filter(e -> e.getRole().equals("Manager"))
                .collect(Collectors.toList());

for (Employee manager : managers) {
    department.removeEmployee(manager);
}

CodePudding user response：

Not tested but should work fine: Try tweaking your code a little like this:

Set<Employee>employees= new HashSet<>();
for (Employee employee : department.getEmployees()) {
     if (employee.getRole().equals("Manager")) {
        employees.add(employee);
     }
}

department.setEmployees(employees);//I assume you have a setter
departmentRepository.save(department); //I hope you understand what departmentRepository means

Here you are reassigning the valid employees list. You could follow another method, instead of deleting each entity separately, you could call a bulk-save using saveAll(...) method on the valid list.