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Spring- Postman too many information with ManyToMany

I have a problem with my Spring application- am practicing ManyToMany Relationship.
I made two Entity- student, and groups for them- everything is good but when am trying to display them in postman i have spaghetti result like :
{"id":4,"lastName":"guzik","groups":[{"id":1,"groupName":"grupka","students":
....(shorter version, its about 1000 lines)
[{"id":1,"lastName":"smith","groups":[{}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}]}{"timestamp":"2022-04-25T08:25:31.387+00:00","status":200,"error":"OK","path":"/api/student/4"}
What am doing wrong ?
enter code here
#RestController
#RequestMapping("/api")
public class MainController{
#Autowired
GroupRepo groupRepo;
#Autowired
StudentRepo studentRepo;
#GetMapping("/student/{id}")
ResponseEntity<?> getStudent(#PathVariable long id){
Optional<Students> student=studentRepo.findById(id);
return ResponseEntity.ok().body(student);
}
#GetMapping("/group/{id}")
ResponseEntity<?> getGroup(#PathVariable long id){
Optional<Groupssss> group=groupRepo.findById(id);
return ResponseEntity.ok().body(group);
}
#GetMapping("/student/{id}/groups")
ResponseEntity<?> studentGroups(#PathVariable long id){
Students student=studentRepo.findById(id).orElseThrow(()-> new UsernameNotFoundException("student not found"));
return ResponseEntity.ok().body(student.getGroups());
}
#PostMapping("/add")
#Transactional
ResponseEntity<?> addStudentToGroup(#RequestHeader long id) throws Exception{
Students student=studentRepo.findById(id)
.orElseThrow(()-> new UsernameNotFoundException("student not found"));
Groupssss group=groupRepo.findByGroupName("grupka").orElseThrow(Exception::new);
student.addGroup(group);
studentRepo.save(student);
return ResponseEntity.ok().build();
}
#Entity
public class Groupssss {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
private String groupName;
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
},
mappedBy = "groups")
private Set<Students> students=new HashSet<>();
public void setGroupName(String groupName) {
this.groupName = groupName;
}
public void setStudents(Set<Students> students) {
this.students = students;
}
public Set<Students> getStudents() {
return students;
}
public String getGroupName() {
return groupName;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
}
#Entity
#Table(name="students")
public class Students {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
long id;
String firstName;
String lastName;
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
})
#JoinTable(name="student_group",
joinColumns = #JoinColumn(name="student_id"),
inverseJoinColumns = #JoinColumn(name="group_id"))
Set<Groupssss> groups=new HashSet<>();
public Students(){}
public Students(String firstName, String lastName){
this.firstName=firstName;
this.lastName=lastName;
}
public void addGroup(Groupssss group){
this.groups.add(group);
group.getStudents().add(this);
}
public Set<Groupssss> getGroups() {
return groups;
}
public String getLastName() {
return lastName;
}
public String getName() {
return firstName;
}
public void setGroups(Set<Groupssss> groups) {
this.groups = groups;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public void setName(String firstName) {
this.firstName = firstName;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
}

If you use ManyToMany relationship, It calls the Parent and the Child entity recursively when you try to get List of it. There must be ignorance in child entity like:
In Parent entity you could call #JsonManagedReference
In Child entity you could call #JsonBackReference
Documentation is here:
Bidirectional Relationships
public class User {
public int id;
public String name;
#JsonManagedReference
public List<Item> userItems;
}
public class Item {
public int id;
public String itemName;
#JsonBackReference
public User owner;
}
Or you can use #JsonIgnore on top of the Parent declaration in Child entity. Some of the case it gets worst when you use JsonIgnore.
Documentation is here:
Jackson Ignore Properties
public class MyDto {
private String stringValue;
#JsonIgnore
private int intValue;
private boolean booleanValue;
public MyDto() {
super();
}
}
Or use #JsonIgnoreProperties when you need to ignore many fields
#JsonIgnoreProperties(value = { "intValue" })
public class MyDto {
private String stringValue;
private int intValue;
private boolean booleanValue;
public MyDto() {
super();
}
}
!Enjoy

How to insert a json body with multiple data to multiple tables with relationship in springboot

I have two entities: UserEntity and LoginEntity and crudrepositories for each. The entities have a relationship of OneToOne where one user will have one login account. I also created a controller and I can get all the data from the database i.e when call getalluser I get all users with their relationship to login. and when I call getAllLogins I get all logins accounts. I also managed to insert the user and the login using API each individually and it's working fine but this will omit the foreign-key user_id.
Now since am knew am stack on how to insert the user and login each respectively with their relationships through one json body
#Entity#Table(name="user_table")public class UserEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long uid;
private String fname;
private String lname;
#OneToOne( cascade = CascadeType.ALL, mappedBy = "userEntityFk")
private LoginEntity logins;
public UserEntity() {
super();
}
public Long getUid() {
return uid;
}
public void setUid(Long uid) {
this.uid = uid;
}
public String getFname() {
return fname;
}
public void setFname(String fname) {
this.fname = fname;
}
public String getLname() {
return lname;
}
public void setLname(String lname) {
this.lname = lname;
}
public LoginEntity getLogins() {
return logins;
}
public void setLogins(LoginEntity logins) {
this.logins = logins;
}
public UserEntity(Long uid, String fname, String lname, LoginEntity logins) {
super();
this.uid = uid;
this.fname = fname;
this.lname = lname;
this.logins = logins;
}
#Entity #Table(name="login_table") public class LoginEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long lid;
private String username;
private String password;
#OneToOne(cascade = CascadeType.ALL )
private UserEntity userEntityFk;
public LoginEntity() {
super();
}
public LoginEntity(Long lid, String username, String password, UserEntity userEntityFk) {
super();
this.lid = lid;
this.username = username;
this.password = password;
this.userEntityFk = userEntityFk;
}
public Long getLid() {
return lid;
}
public void setLid(Long lid) {
this.lid = lid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public UserEntity getUserEntityFk() {
return userEntityFk;
}
public void setUserEntityFk(UserEntity userEntityFk) {
this.userEntityFk = userEntityFk;
}
}
#Repository
public interface LoginRepo extends CrudRepository<LoginEntity, Integer> {
}
#Repository
public interface UserRepo extends CrudRepository<UserEntity, Integer> {
}
#RestController
#RequestMapping(path="/api")
public class MainController {
#Autowired
private UserRepo userRepository;
#Autowired
private LoginRepo loginRepository;
//===this works fine i can get all the users after insert
#GetMapping(path="/user_acc")
public #ResponseBody Iterable<UserEntity> getAllUsers() {
// This returns a JSON or XML with the users
return userRepository.findAll();
}
//================this too works fine after insert
#GetMapping(path="/login_acc")
public #ResponseBody Iterable<LoginEntity> getAlllogins() {
// This returns a JSON or XML with the users
return loginRepository.findAll();
}
//===adding single user works fine. and it returns user_id
#PostMapping("/user_acc")
public Long addNewUser(#RequestBody UserEntity userz){
UserEntity ue = userRepository.save(userz);
return ue.getUid();
}
//===this works but the foreign key not inserted and thats where my problem is
#PostMapping("/login_acc")
public LoginEntity addNewLogin(#RequestBody LoginEntity loginz){
return loginRepository.save(loginz);
}
}
class UserLogin{
UserEntity myuser;
LoginEntity mylogin;
public UserEntity getMyuser() {
return myuser;
}
public void setMyuser(UserEntity myuser) {
this.myuser = myuser;
}
public LoginEntity getMylogin() {
return mylogin;
}
public void setMylogin(LoginEntity mylogin) {
this.mylogin = mylogin;
}
}
result on post http://localhost:8080/api/login_acc. account created but no foreign key
result on post http://localhost:8080/api/login_acc. account created but no foreign key
{
"lid": 1,
"username": "admin1",
"password": "11111",
"userEntityFk": null
}
result on geting all users on get method http://localhost:8080/api/user_acc
{
"uid": 1,
"fname": "hassan",
"lname": "zahor",
"logins": null
}
what i want to post is this body below to multiple tables
{
"fname":"hassan",
"lname":"zahor",
"username": "admin5",
"password": "55555"
}

This one should works better :
{
"fname":"hassan",
"lname":"zahor",
"userEntityFk" : {
"username": "admin5",
"password": "55555"
}
}
However, you will get an error if your endpoint returns an object that contains a loop inclusion : spring will try to map it into json indefinitely.
You can correct this issue to map your result into another object before returning it from your controller, or just remove the property "logins" from UserEntity.

Hibernate adds unnecessary row in role table after user registration

I'm trying to add a functionality to my webapp with user registration. Webapp is based on spring boot, hibernate and mysql database, frontend is in angular. Generally, the user creation procedure is working correctly, user data is correctly send from frontend to backend via json and saved to the database in shop_user table (with all the user data, such as name, surname, address etc.), but it DOESN'T have role column.
I also have table 'role', which should be:
id name
1 USER
2 ADMIN
and joined table user_role, which consists of user_id from table shop_user and role id from table role, so it should look like this:
id_user id_role
1 2
2 1
3 1
When user is being created on the website, it is hard-coded to set the role by default to USER. This seems to work quite well as it adds a new row in shop_user, and it adds a row to user_role, but... it also creates a new row in 'role' table.
so in the end 'role' table looks like this:
id name
1 ADMIN
2 USER
3 USER
4 USER
5 USER
99 USER
`
while this is not a blocking bug that stops application from working, it is not 'as it should work' unfortunately... as the table should only consist of two role rows (and possibly additional ones, in the future), but not multiplicated for each user!
here's the flawed code of user:
User
#Entity
#Table(name = "shop_user")
public class User extends AbstractEntity {
#Column
private String firstName;
#Column
private String lastName;
#Column
private String addressLine;
#Column
private String city;
#Column
private String country;
#Column
private String zipCode;
#Column
private String phoneNumber;
#Column
private String email;
#Column
private String password;
#ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#JoinTable(name = "user_role",
joinColumns = #JoinColumn(name = "id_user", referencedColumnName = "id"),
inverseJoinColumns = #JoinColumn(name = "id_role", referencedColumnName = "id"),
uniqueConstraints = {#UniqueConstraint(columnNames = {"id_user", "id_role"})})
private List<Role> roles;
public User() {
}
public User(User user) {
setId(user.getId());
this.firstName = user.getFirstName();
this.lastName = user.getLastName();
this.addressLine = user.getAddressLine();
this.city = user.getCity();
this.country = user.getCountry();
this.zipCode = user.getZipCode();
this.phoneNumber = user.getPhoneNumber();
this.email = user.getEmail();
this.password = user.getPassword();
this.roles= user.getRoles();
}
public List<Role> getRoles() {
return roles;
}
public void setRoles(List<Role> roles) {
this.roles = roles;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getAddressLine() {
return addressLine;
}
public void setAddressLine(String addressLine) {
this.addressLine = addressLine;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
public String getZipCode() {
return zipCode;
}
public void setZipCode(String zipCode) {
this.zipCode = zipCode;
}
public String getPhoneNumber() {
return phoneNumber;
}
public void setPhoneNumber(String phoneNumber) {
this.phoneNumber = phoneNumber;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
Role implementation:
Role
#Entity
#Table(name = "role")
public class Role extends AbstractEntity {
#Column
private String name;
#ManyToMany(mappedBy = "roles", cascade = CascadeType.PERSIST)
private List<User> users;
public Role(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<User> getUsers() {
return users;
}
public void setUsers(List<User> users) {
this.users = users;
}
}
Abstract entity:
AbstractEntity
#MappedSuperclass
public abstract class AbstractEntity implements Persistable<Long> {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
public void setId(Long id) {
this.id = id;
}
#Override
public Long getId() {
return id;
}
#Override
public boolean isNew() {
return id == null;
}
}
User service:
UserServiceImpl
#Service
public class UserServiceImpl extends AbstractServiceImpl<User, UserDTO> implements UserService {
private final UserRepository userRepository;
private final UserConverter userConverter;
public UserServiceImpl(UserRepository userRepository, UserConverter
userConverter) {
this.userRepository = userRepository;
this.userConverter = userConverter;
}
#Override
protected JpaRepository<User, Long> getRepository() {
return userRepository;
}
#Override
protected Converter<User, UserDTO> getConverter() {
return userConverter;
}
#Override
#Transactional
public User registerUser(User user) {
List<Role> roles = new LinkedList<>();
roles.add(new Role("USER"));
user.setRoles(roles);
return userRepository.save(user);
}}
I am nearly sure that this comes to the relations mapping in Hibernate and object creation, but can't quite figure it out...
Any help will be appreciated, thank you!

The issue is here:
#Override
#Transactional
public User registerUser(User user) {
List<Role> roles = new LinkedList<>();
roles.add(new Role("USER"));
user.setRoles(roles);
return userRepository.save(user);
}}
Since the relationship User -> Role is cascade persist, the (new) role new Role("USER") is also persisted and you ended up with a new Role for each user instead of reusing the existing one.
The solution is to check the existence of a Role with name = USER. If doesn't exist, insert it. Otherwise add the existent one to the roles collection.

How to update one field in my Entity using JPA Repository

I have Entity with 3 fields: id, lastname and phoneNumber. I want to create method which works for update all fields or only one or two.
I use Hibernate and JPA Repository.
When I try to update all fields everything works well but when for example i want to update only lastname without changing of phoneNumber I have in output null insted of old phoneNumber.
Here is my method from Controller:
#PutMapping("/students/update/{id}")
public String updateStudentById(#ModelAttribute Student student, #ModelAttribute StudentDetails studentDetails,
String lastname, String phoneNumber,
#PathVariable Long id) {
Optional<Student> resultOptional = studentRepository.findById(id);
//Student result =resultOptional.get();
resultOptional.ifPresent((Student result) -> {
result.getStudentDetails().setPhoneNumber(studentDetails.getPhoneNumber()); result.getStudentDetails().setLastname(studentDetails.getLastname());
studentRepository.save(result);
});
return "Student updated";
}
The class for update:
#DynamicUpdate
#Entity
public class StudentDetails {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(name="lastname")
private String lastname;
#Column(name="phone_number")
private String phoneNumber;
public StudentDetails() {
}
public StudentDetails(Long id, String lastname, String phoneNumber) {
this.id = id;
this.lastname = lastname;
this.phoneNumber = phoneNumber;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getLastname() {
return lastname;
}
public void setLastname(String lastname) {
this.lastname = lastname;
}
public String getPhoneNumber() {
return phoneNumber;
}
public void setPhoneNumber(String phoneNumber) {
this.phoneNumber = phoneNumber;
}
}
The class which has relation with StudentDetails:
#Entity
#Table(name = "student")
#DynamicUpdate
public class Student {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(name = "name")
private String name;
#Column(name = "email")
private String email;
//#OneToMany(mappedBy = "student")
#ManyToMany
#JoinTable(name="course_student",joinColumns = #JoinColumn(name="student_id"),
inverseJoinColumns = #JoinColumn(name="course_id"))
private List<Courses> courses;
#OneToOne(cascade = CascadeType.ALL)
// #JoinColumn(name="studen/_details_id") // with this we have dobule student_details column
private StudentDetails studentDetails;
public List<Courses> getCourses() {
return courses;
}
public void setCourses(List<Courses> courses) {
this.courses = courses;
}
public StudentDetails getStudentDetails() {
return studentDetails;
}
public void setStudentDetails(StudentDetails studentDetails) {
this.studentDetails = studentDetails;
}
// Methods for StudentViewController
public String getLastname(){
return studentDetails.getLastname();
}
public String getPhoneNumber(){
return studentDetails.getPhoneNumber();
}
public Student() {
}
public Student(String name, String email, StudentDetails studentDetails) {
// this.id = id;
this.name = name;
this.email = email;
this.studentDetails = studentDetails;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
#Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", email='" + email + '\'' +
'}';
}
}
I was looking for solution and I added #DynamicUpdate but still it doesn't work.

Your code works properly. When you only provide lastName parameter in your request, then the phoneNumber parameter will be mapped to null so you override the phoneNumer property in your entity with this null value.
Change the code in the following way:
resultOptional.ifPresent((Student result) -> {
if(studentDetails.getPhoneNumber()!=null) {
result.getStudentDetails().setPhoneNumber(studentDetails.getPhoneNumber());
}
if(studentDetails.getLastname()!=null) {
result.getStudentDetails().setLastname(studentDetails.getLastname());
}
studentRepository.save(result);
});
Unfortunately it raises an other problem: How will you delete these fields? (How can you set them explicitly to null? )
A possible solution if you check for the "" (empty string) and set the property to null if the parameter is empty string.
It will be a quite messy code anyway...
You should consider using the Spring Data Rest package. It automatically creates all of the standard REST endpoints for your entities and handles all of these PUT/PATCH/POST/DELETE issues out of the box.

why don't you just set the params of your request in you setters?
resultOptional.ifPresent((Student result) -> {
result.getStudentDetails().setPhoneNumber(phoneNumber);
result.getStudentDetails().setLastname(lastname);
studentRepository.save(result);
});

You forget set #OneToOne mapping in StudentDetails - StudentDetails also need field of type Student which will be annotated #OneToOne.
Also you have to ensure, that all of entity fields will be filled - read more about fetch types.

Spring boot+jersey api+ JPA : failed to lazily initialize a collection of role

I am new with using spring boot + jersey api + JPA.
I hava three entity that uses one to many bidirectional mapping. When i used spring boot + jersey api+ JPA I get error :
failed to lazily initialize a collection of role: com.kavinaam.GSTbilling.entity.Country.states, could not initialize proxy - no Session (through reference chain: java.util.ArrayList[0]->com.kavinaam.GSTbilling.entity.City["states"]->com.kavinaam.GSTbilling.entity.States["countyId"]->com.kavinaam.GSTbilling.entity.Country["states"])
I have added my entity, dao , services and end point.
#Entity
#Table(name="country")
public class Country implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name="id")
private int id;
#Column(name="countryName")
private String countryName;
#OneToMany(mappedBy = "countyId",cascade = CascadeType.ALL)
private Set<States> states;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getCountryName() {
return countryName;
}
public void setCountryName(String countryName) {
this.countryName = countryName;
}
public Set<States> getStates() {
return states;
}
public void setStates(Set<States> states) {
this.states = states;
}
}
My state class:
#Entity
#Table(name="states")
public class States implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name="id")
private int id;
#ManyToOne
#JoinColumn(name="countyId")
private Country countyId;
#Column(name="stateName")
private String stateName;
#OneToMany(mappedBy = "states", cascade = CascadeType.ALL)
private Set<City> city;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public Country getCountyId() {
return countyId;
}
public void setCountyId(Country countyId) {
this.countyId = countyId;
}
public String getStateName() {
return stateName;
}
public void setStateName(String stateName) {
this.stateName = stateName;
}
public Set<City> getCity() {
return city;
}
public void setCity(Set<City> city) {
this.city = city;
}
}
My city class:
#Entity
#Table(name="cities")
public class City implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name="id")
private int id;
#ManyToOne
#JoinColumn(name="stateId")
private States states;
#Column(name="cityName")
private String cityName;
#Column(name="zip")
private String zip;
public void setId(int id) {
this.id = id;
}
public void setZip(String zip) {
this.zip = zip;
}
public States getStates() {
return states;
}
public void setStates(States states) {
this.states = states;
}
public String getCityName() {
return cityName;
}
public void setCityName(String cityName) {
this.cityName = cityName;
}
public String getZip() {
return zip;
}
public int getId() {
return id;
}
}
My DAO:
#Transactional
#Repository
public class GSTCityDAO implements IGSTCityDAO {
#PersistenceContext
private EntityManager entityManager;
//#SuppressWarnings("unchecked")
#Override
public List<City> getAllCities() {
//Session session = sessionFactory.getCurrentSession();
String hql = "FROM City as ct ORDER BY ct.id";
List<City> l = entityManager.createQuery(hql,City.class).getResultList();
return l;
}
#Override
public City getCityById(int cityId) {
return entityManager.find(City.class, cityId);
}
#SuppressWarnings("unchecked")
#Override
public List<City> getCityByStateId(States stateId) {
String getcitybystate = " FROM City as c WHERE c.states = ?";
return (List<City>) entityManager.createQuery(getcitybystate).setParameter(1, stateId).getResultList();
}
#Override
public void addCity(City city) {
entityManager.persist(city);
}
#Override
public void updateCity(City city) {
City cityctl = getCityById(city.getId());
cityctl.setCityName(city.getCityName());
cityctl.setZip(city.getZip());
cityctl.setStates(city.getStates());
entityManager.flush();
}
#Override
public void deleteCity(int cityId) {
entityManager.remove(getCityById(cityId));
}
#Override
public boolean cityExists(String name, String zip) {
String hql = "FROM City WHERE cityName = ? and zip = ?";
int count = entityManager.createQuery(hql).setParameter(1,name).setParameter(2, zip).getResultList().size();
return count > 0 ? true : false;
}
}
Services:
#Service
public class GSTCityService implements IGSTCityService {
#Autowired
private IGSTCityDAO cityDAO;
#Override
public List<City> getAllCities() {
List<City> l = cityDAO.getAllCities();
Hibernate.initialize(l);
return l;
}
public List<City> getCityByStateId(States stateId) {
return cityDAO.getCityByStateId(stateId);
}
#Override
public City getCityById(int cityId) {
City city = cityDAO.getCityById(cityId);
return city;
}
#Override
public synchronized boolean addCity(City city) {
if(cityDAO.cityExists(city.getCityName(), city.getZip())){
return false;
}else{
cityDAO.addCity(city);
return true;
}
}
#Override
public void updateCity(City city) {
cityDAO.updateCity(city);
}
#Override
public void deleteCity(int cityId) {
cityDAO.deleteCity(cityId);
}
}
End Point:
#Component
#Path("/")
public class Test {
private static final Logger logger = LoggerFactory.getLogger(Test.class);
#Autowired
private IGSTCityService cityService;
#GET
#Path("/hi")
#Produces(MediaType.APPLICATION_JSON)
public Response hello(){
return Response.ok("Hello GST").build();
}
#GET
#Path("/test")
#Produces(MediaType.APPLICATION_JSON)
public Response getAllDate(){
List<City> list = cityService.getAllCities();
for(City city: list){
System.out.println(city);
}
return Response.ok(list).build();
}
#GET
#Path("/test/{id}")
#Produces(MediaType.APPLICATION_JSON)
public Response getAllDateBySome(#PathParam("id") Integer id){
States state = new States();
state.setId(id);
List<City> list = cityService.getCityByStateId(state);
return Response.ok(list).build();
}
#GET
#Path("/{id}")
#Produces(MediaType.APPLICATION_JSON)
public Response getDataById(#PathParam("id")Integer id){
City citl = cityService.getCityById(id);
return Response.ok(citl).build();
}
#POST
#Path("/add")
#Consumes(MediaType.APPLICATION_JSON)
public Response addData(City city){
boolean isAdded = cityService.addCity(city);
if(!isAdded){
return Response.status(Status.CONFLICT).build();
}
return Response.created(URI.create("/gst/"+ city.getId())).build();
}
#PUT
#Path("/update")
#Produces(MediaType.APPLICATION_JSON)
#Consumes(MediaType.APPLICATION_JSON)
public Response updateCountry(City city){
cityService.updateCity(city);
return Response.ok(city).build();
}
#DELETE
#Path("/{id}")
#Consumes(MediaType.APPLICATION_JSON)
public Response deleteCountry(#PathParam("id")Integer id){
cityService.deleteCity(id);
return Response.noContent().build();
}
}
I am using import org.springframework.transaction.annotation.Transactional; for transnational in DAO. Also I can not use #PersistenceContext(type=PersistenceContextType.EXTENDED) and fetch type Eager because I get error of Maximum stack size exceeded

I solved it by using the #JsonBackReference on OneToMany relationship. The problem is with the Serialization and Deserialization.
" the property annotated with #JsonManagedReference annotation is handled normally (serialized normally, no special handling for deserialization) and the property annotated with #JsonBackReference annotation is not serialized; and during deserialization, its value is set to instance that has the "managed" (forward) link."

You should do one or both of the following:
1) Move the #Transactional from DAO to Service. Thats a good idea in general as usually are still processing the result entities in some way on that layer.
2) Fetch the dependencies in the queries explicitly:
select ct FROM City as ct inner join fetch ct.states s ORDER BY ct.id