Spring Data JPA OneToOne Mapping returning Null - spring

Question

I have two Entity classes, each for my Table. They both are OneToOne-Mapped. When I read the Data, am always getting the other table's value as null.
These are my SQLs
CREATE TABLE driver_master (
unique_driver_id VARCHAR(60) PRIMARY KEY,
driver_name TEXT,
mobile_number VARCHAR (20),
vehicle_number TEXT,
vehicle_make TEXT,
seating_capacity INTEGER (10),
creation_time DATETIME
)
CREATE TABLE user_master (
user_id MEDIUMINT AUTO_INCREMENT PRIMARY KEY,
user_name TEXT,
password VARCHAR (20),
unique_driver_id VARCHAR(60),
FOREIGN KEY (unique_driver_id) REFERENCES driver_master(unique_driver_id)
)
These are my Entity classes
DriverMaster.java
#Data
#Builder
#NoArgsConstructor
#AllArgsConstructor
#Entity
#Table(name = "driver_master")
public class DriverMaster {
#Id
#GeneratedValue(generator = "uuid2")
#GenericGenerator(name = "uuid2", strategy = "org.hibernate.id.UUIDGenerator")
#Column(name = "unique_driver_id")
UUID id;
#Column(name = "driver_name")
String driverName;
#Column(name = "mobile_number")
String mobileNumber;
#Column(name = "vehicle_number")
String vehicleNumber;
#Column(name = "vehicle_make")
String vehicleMake;
#Column(name = "seating_capacity")
Integer seatingCapacity;
#Column(name = "creation_time")
OffsetDateTime creationTime;
#OneToOne(cascade = CascadeType.ALL, mappedBy = "driverMaster")
UserMaster userMaster;
}
UserMaster.java
#Data
#Builder
#NoArgsConstructor
#AllArgsConstructor
#Entity
#Table(name = "user_master")
public class UserMaster {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "user_id")
Long id;
#Column(name = "user_name")
String userName;
#Column(name = "password")
String password;
#OneToOne(fetch = FetchType.EAGER)
#JoinColumn(name = "unique_driver_id", nullable = false)
DriverMaster driverMaster;
}
This is my DriverMasterRepository
public interface DriverMasterRepository extends CrudRepository<DriverMaster, Long> {
DriverMaster findById(UUID id);
}
This is my UserMasterRepository
public interface UserMasterRepository extends CrudRepository<UserMaster, Long> {
UserMaster findById(Long id);
}
I am creating DriverMaster and UserMaster at the same time. Code Snippet below
public DriverMaster create() {
UserMaster userMaster = UserMaster.builder()
.userName("xxxxx")
.password("xxxx").build();
DriverMaster driverMaster = DriverMaster.builder().driverName("TestDriver")
.creationTime(ZonedDateTime.now().toOffsetDateTime())
.seatingCapacity(8)
.mobileNumber("xxxxxxx")
.vehicleNumber("xxxx")
.vehicleMake("xxxx")
.userMaster(userMaster)
.build();
return driverUserService.create(driverMaster);
}
When i access each repository and get the data, the data for that particular table is getting populated while the referenced Object is always coming as Null.
After creation of DriverMaster, I couldn't get UserMaster within DriverMaster, it is always coming as null .
The REST Response below shows that UserMaster within DriverMaster is coming as Null
{
"id": "0d97073b-6ae2-47a9-b751-0313fd9e8ba2",
"driverName": "TestDriver",
"mobileNumber": "11111",
"vehicleNumber": "111",
"vehicleMake": "figo",
"seatingCapacity": 8,
"creationTime": "2018-02-16T15:56:50.331Z",
"userMaster": null
}

Answer 1

it's not a 100% problem's reason, but I believe you have to add an implementation of Serializableinterface into your entity classes.