Getting null value reference in One to Many mapping in Spingboot

I am trying to implement ONE-to-MANY mapping among two entities. In here designations have a location and a location have many designations. Once I added the designation it mapped fine, but it update the location table with null except id.

Here I’m using the Microsoft SQL server. Application Properties

#for ms server
spring.datasource.url = jdbc:sqlserver://localhost\sqlexpress;databaseName=nifs_database;encrypt=true;trustServerCertificate=true
spring.datasource.username = viranga
spring.datasource.password = ********

spring.jpa.hibernate.ddl-auto=update
spring.jpa.properties.hibernate.format_sql = true
spring.jpa.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.properties.hibernate.globally_quoted_identifiers=true
#spring.main.allow-circular-references=true
spring.jackson.serialization.fail-on-empty-beans=false

DesignationMaster

package com.nifs.backend.Admin.EmployeeDesignation;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.nifs.backend.Admin.Locations.Locations;
import jakarta.persistence.*;
import lombok.*;
import java.util.Date;

@Entity
@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
@Table(name = "designation_master")
public class DesignationMaster {

    @Id
    @Column(name = "id", nullable = false, length = 10)
    private String id;

    @Column(name = "designation_name", length = 255)
    private String designationName;

    @ManyToOne(fetch = FetchType.LAZY, cascade = {CascadeType.MERGE})
    @JoinColumn(name = "location_id", referencedColumnName = "location_id", nullable = false)
    @JsonIgnoreProperties("designations")
    private Locations location;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name="date_created")
    private Date dateCreated;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name="date_updated")
    private Date dateUpdated;
}

LocationMaster

package com.nifs.backend.Admin.Locations;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.nifs.backend.Admin.EmployeeDesignation.DesignationMaster;
import com.nifs.backend.Admin.OtherData.District;
import jakarta.persistence.*;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import java.util.Date;
import java.util.List;
import java.util.Set;

@Entity
@Setter
@Getter
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "locations_master")
public class Locations {

    @Id
    @Column(name = "location_id", nullable = false, length = 10)
    private String locationId;

    @Column(name = "location_name", length = 100)
    private String locationName;

    @Column(name = "address", length = 255)
    private String address;

    @Column(name = "tel_no", length = 15)
    private String telNo;

    @Column(name = "fax_no", length = 15)
    private String faxNo;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name="date_created")
    private Date dateCreated;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name="date_updated")
    private Date dateUpdated;

//    relationships

    @OneToMany(mappedBy = "location", cascade = {CascadeType.MERGE}, fetch = FetchType.LAZY)
    @JsonIgnoreProperties("location")
    private List<DesignationMaster> designations;

}

Service class of Designations

@Service
public class DesignationService {

    @Autowired
    private DesignationRepostory desRepo;

    @Autowired
    private LocationRepository locRepo;

//    get all designations
    public List<DesignationMaster> getAllDesignations() {
        return desRepo.findAll();
    }

    public Boolean createDesignation(DesignationMaster desData) {
        if(desRepo.returnDesignation(desData.getId()) == null){
            Date d = new Date();
            desData.setDateCreated(d);
            desRepo.save(desData);
            return true;
        }
        return false;
    }
}

Controller class of Designation

@RestController
@RequestMapping("admin/designation")
public class DesignationController {

    @Autowired
    private DesignationService desService;

//    get all designations
    @GetMapping
    private List<DesignationMaster> getAllDesignations(){
        return desService.getAllDesignations();
    }

    @GetMapping("/newid")
    private String returnNewId(){
        return desService.returnNewId();
    }
//    create designation
    @PostMapping
    private Boolean createDesignation(@RequestBody DesignationMaster desData){
        return desService.createDesignation(desData);
    }

I pass data to backend as this

{
    "id": "DM1003",
    "designationName": "Driver",
    "location": {
          "locationId": "LM1001"
    }
}

And it updated the database, but it change others values to null in location table, and get request like this

{
        "id": "DM1001",
        "designationName": "Lecturer",
        "location": {
            "locationId": "LM1001",
            "locationName": null,
            "address": null,
            "telNo": null,
            "faxNo": null,
            "dateCreated": null,
            "dateUpdated": null,
            "hibernateLazyInitializer": {}
        },
        "dateCreated": "2022-12-21T13:56:32.429+00:00",
        "dateUpdated": null
    }

As in the database -Location table

-Designation table

I went through many methods but nothing works for me. Is there anyone who can make my day better?

Answer

Its work after change the createDesignation(DesignationMaster desData) in service class as follows

   public Boolean createDivision(DivisionMaster diviMasterData) {
        if (diviMasterRepo.returnDivision(diviMasterData.getDivisionId()) == null) {
            Date d = new Date();
            diviMasterData.setCreatedDate(d);
            Locations l = locRepo.getLocation(diviMasterData.getLocation().getLocationId());
            diviMasterData.setLocation(l);
            diviMasterRepo.save(diviMasterData);
            return true;
        } else {
            return false;
        }

    }

where I fetch the location data from its repository and set that object to the destination object. So that its work fine.