#OneToMany mapped by doesn't make an entry to the table - spring

Question

Here I have two entity class. I used OneToMany and ManyToOne mapping.
#Entity
#Table(name="test_user")
public class TestUser {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer user_id;
private String user_name;
#OneToMany(mappedBy = "testuser", fetch=FetchType.EAGER, cascade = CascadeType.ALL)
private Set<UserAnswer> answer = new HashSet<UserAnswer>();
public Set<UserAnswer> getAnswer() {
return answer;
}
public void setAnswer(Set<UserAnswer> answer) {
this.answer = answer;
}
public Integer getUser_id() {
return user_id;
}
public void setUser_id(Integer user_id) {
this.user_id = user_id;
}
public String getUser_name() {
return user_name;
}
public void setUser_name(String user_name) {
this.user_name = user_name;
}
}
This is my second entity class
#Entity
#Table(name="user_answer")
public class UserAnswer {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer answer_id;
private String answer;
#ManyToOne
#JoinColumn(name="user_id")
private TestUser testuser;
public TestUser getTestuser() {
return testuser;
}
public void setTestuser(TestUser testuser) {
this.testuser = testuser;
}
public Integer getAnswer_id() {
return answer_id;
}
public void setAnswer_id(Integer answer_id) {
this.answer_id = answer_id;
}
public String getAnswer() {
return answer;
}
public void setAnswer(String answer) {
this.answer = answer;
}
}
When I insert user and answer, user_id is not getting stored in user_answer table.
Here is my JSON input format.
{
"user_name":"myname",
"answer":[
{
"answer":"myanswer"
}
]
}
When I fetch the data I am getting JSON response like this,
[
{
"user_id": 52,
"user_name": "myname",
"answer": []
}
]
Here is my service code snippet,
#Autowired
private TestUserRepository repo;
#Override
public TestUser addUser(TestUser user) {
return repo.save(user);
}
Here is my controller code snippet
#Autowired
private TestUserApiService service;
#RequestMapping(value = "/saveuser", produces = { "application/json" }, consumes = { "application/json" }, method = RequestMethod.POST)
public ResponseEntity<TestUser> addUser(#RequestBody TestUser user)
throws NotFoundException {
return new ResponseEntity<TestUser>(service.addUser(user),
HttpStatus.OK);
}

Answer 1

The relation you have here is bidirectional, which means each side of the relation should have a reference to the other side.
Your input format has TestUser which has a UserAnswer set since you are cascading your UserAnswer inside your TestUser you would expect to persist the relation, but your UserAnswer should have a reference to TestUser as well to complete the relations.
you can do two things, first you can make your relation unidirectional, or you can extract the coming UserAnswer and inject the TestUser to them then persist the TestUser