[FIXED] Spring Boot auto generate association table with attibute

Issue

I'm auto generating entities within the database which works great using:

spring.jpa.hibernate.ddl-auto=update

Now I need an additional attribute within the association table and I can't figure it out without creating an association entity by hand. The current classes listed below generate an association table without the additional attribute.

The tables I need:

    persons:
    id
    
    search_requests:
    id
    
    search_requests_persons:
    person_id
    search_request_id
    study_id  

The classes I currently have (simplified):

@NoArgsConstructor
@RequiredArgsConstructor(staticName = "of")
@Getter
@Setter
@Entity
@EqualsAndHashCode
@Table(name = "persons")
public class Person {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
    private Long id;
    
    // The following line is what I would need
    // private List<Integer> studyIds;
}

@NoArgsConstructor
@RequiredArgsConstructor(staticName = "of")
@Getter
@Setter
@Entity
@EqualsAndHashCode
@Table(name = "search_requests")
public class SearchRequest {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
    private Long id;

    @NonNull
    @ManyToMany
    private List<Person> persons;
}

I'm using Lombok and Javax Persistence for the annotations.

Solution

In order to add additional attributes in your JoinTable, you could manually create your JoinTable entity. e.g: PersonSearchRequest.java

@Entity
@Table(name = "person_search_request)
@Getter
@Setter
@NoArgsConstructor
public class PersonSearchRequest {
    @EmbeddedId
    private PersonSearchRequestPK id;
    
    // put your additional attribute here, e.g:
    private String attribute1;
    private Long attribute2;
    @ElementCollection
    private List<String> attribute3s; 

    @Embeddable
    @Getter
    @Setter
    @AllArgsConstructor
    @NoArgsConstructor
    public static class PersonSearchRequestPK implements Serializable {
        @ManyToOne(fetch = FetchType.LAZY)
        private Person person;

        @ManyToOne(fetch = FetchType.LAZY)
        private SearchRequest searchRequest;
    }

}

Person.java

@NoArgsConstructor
@RequiredArgsConstructor(staticName = "of")
@Getter
@Setter
@Entity
@EqualsAndHashCode
@Table(name = "persons")
public class Person {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
    private Long id;
    
    @OneToMany(mappedBy = "id.person")
    private List<PersonSearchRequest> personSearchRequests;
}

SearchRequest.java

@NoArgsConstructor
@RequiredArgsConstructor(staticName = "of")
@Getter
@Setter
@Entity
@EqualsAndHashCode
@Table(name = "search_requests")
public class SearchRequest {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
    private Long id;

    @OneToMany(mappedBy = "id.searchRequest")
    private List<PersonSearchRequest> personSearchRequests;
}

Answered By - Linh Vu