JPA serialize enttiy - json

Question

I have my data model that contains 3 tables: User, Profile, UserProfile.
public class User implements Serializable {
private Integer id;
......
#OneToMany(mappedBy = "user", cascade = CascadeType.ALL, fetch =
FetchType.LAZY)
#JsonManagedReference
#JsonProperty("profiles")
private List<UserProfile> userProfiles = new ArrayList<UserProfile>();
}
public class Profile implements Serializable {
private Integer id;
......
#OneToMany(mappedBy="profile", cascade = CascadeType.ALL, fetch =
FetchType.LAZY)
#JsonBackReference
private List<UserProfile> userProfiles= new ArrayList<UserProfile>();
}
public class UserProfile implements Serializable {
private Integer id;
#ManyToOne
#JoinColumn(name = "idUser")
#JsonBackReference
private User user;
#ManyToOne
#JoinColumn(name = "idProfile")
#JsonManagedReference
private Profile profile;
}
And here’s my json feed back:
{
"id": 1,
.......
"profiles": [
{
"profile": {
"id": 1,
.....
},
{
"id": 2,
.....
}
}
]
}
I have two questions:
Is it possible to remove the profile attribute and have:
{
"id": 1,
.......
"profiles": [
{
"id": 1,
.....
},
{
": 2,
.....
}
]
}
In a manytomany relationship with an intermediate table that contains a primary key (id), 2 foreign key that are the ids of the 2 tables that have the manytomany relationship, is that how to do it?

Answer 1

For the 1st question, to hide profile attribute, there are 2 options:
1. If you don't need it in any json output, you can add a #JsonIgnore annotation to it;
2. If you need it elsewhere but don't want it here, you can use Projection. Check https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#projections and https://www.baeldung.com/spring-data-rest-projections-excerpts for reference on how to use projections.

Answer 2

Checked your code again. Your code has some problem.
You only need 2 entities: User and Profile. And just add #ManyToMany relationship to them.
Refer here for a complete sample on ManyToMany https://vladmihalcea.com/the-best-way-to-use-the-manytomany-annotation-with-jpa-and-hibernate/