Issue in Saving entities with Many to Many relation in SpringData JPA / Hibernate - oracle

Question

I have Many-to-many relation for user to role entity.
So I created Bidirectional mapping with link entity life cycle.
Note: Role table is already prepopulated with the data by other process
Employee.java
#Entity
#Table(name="EMPLOYEE")
public class Employee {
#Id
#GeneratedValue(
strategy = GenerationType.SEQUENCE,
generator = "EMPLOYEE_SEQ"
)
#GenericGenerator(
name = "EMPLOYEE_SEQ",
strategy = "org.hibernate.id.enhanced.SequenceStyleGenerator",
parameters = {
#Parameter(name = "sequence_name", value = "EMPLOYEE_SEQ"),
#Parameter(name = "initial_value", value = "1"),
#Parameter(name = "increment_size", value = "3"),
#Parameter(name = "optimizer", value = "pooled-lo")
}
)
private Long id;
#Column(name="NAME")
private String name;
#OneToMany(mappedBy="employee", cascade= CascadeType.ALL,orphanRemoval=true)
private List<EmployeeRole> roles = new ArrayList<EmployeeRole>();
// Removed setters and getters
#Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.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;
Employee other = (Employee) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
return true;
}
public void addRole(Role role)
{
EmployeeRole employeeRole = new EmployeeRole(this,role);
roles.add(employeeRole);
role.getEmployee().add(employeeRole);
}
}
Role.Java
#Entity
#Table(name="ROLE")
public class Role {
#Id
private Long id;
private String roleName;
#OneToMany(mappedBy="role",cascade = CascadeType.ALL,orphanRemoval= true)
private List<EmployeeRole> employee = new ArrayList<EmployeeRole>();
#Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.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;
Role other = (Role) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
return true;
}
}
EmployeeRole.java
#Entity(name = "EmployeeRole")
public class EmployeeRole implements Serializable {
public EmployeeRole() {
}
public EmployeeRole(Employee employee, Role role) {
super();
this.employee = employee;
this.role = role;
}
/**
*
*/
private static final long serialVersionUID = 1L;
#Id
#ManyToOne
private Employee employee;
#Id
#ManyToOne
private Role role;
#Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((employee == null) ? 0 : employee.hashCode());
result = prime * result + ((role == null) ? 0 : role.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;
EmployeeRole other = (EmployeeRole) obj;
if (employee == null) {
if (other.employee != null)
return false;
} else if (!employee.equals(other.employee))
return false;
if (role == null) {
if (other.role != null)
return false;
} else if (!role.equals(other.role))
return false;
return true;
}
}
EmployeeService.java
#Autowired
EmployeeRepository employeeRepo;
#Autowired
RoleRepository roleRepo;
#Transactional
public void addEmployee(EmployeeDTO employeedto) {
Employee employeeDB = employeeRepo.findByName(employeedto.getEmployeeName());
Role roleDB = roleRepo.findByRoleName(employeedto.getRoles().get(0).getRoleName());
if(employeeDB==null) {
employeeDB = new Employee();
}
employeeDB.setName(employeedto.getEmployeeName());
if(roleDB == null) {
roleDB = new Role();
}
employeeDB.addRole(roleDB);
employeeRepo.save(employeeDB);
}
Problem Statement:
When I save the below Request body, I was able to create the new employee Sara and link the 'Admin' role.
{
"employeeName": "Sara",
"roles": [{
"roleName": "Admin"
}
]
}
But when I try to link another role 'Read' to the same user 'Sara' I am getting the below exception
{
"employeeName": "Sara",
"roles": [{
"roleName": "Read"
}
]
}
Exception:
2019-12-12 14:01:21.625 WARN 41064 --- [nio-8080-exec-3] o.h.engine.jdbc.spi.SqlExceptionHelper : SQL Error: 1400, SQLState: 23000
2019-12-12 14:01:21.625 ERROR 41064 --- [nio-8080-exec-3] o.h.engine.jdbc.spi.SqlExceptionHelper : ORA-01400: cannot insert NULL into ("SCHEMA"."EMPLOYEE_ROLE"."ROLE_ID")
Thoughts on this please.