CODEWITHSUNDEEP
javaspringhibernatejpa
ZhenyaM
ZhenyaM

Reputation: 686

Join two tables in one java object by jpa

I need to join 2 tables into one object with some condition. I have the following:

@Entity
@Table(name = "polling")
public class Polling extends DomainIdObject {

    @ManyToOne
    @JoinColumn(name = "owner_id")
    private Person owner;

    @Column(name = "poll_name")
    private String name;

    @Column(name = "description")
    private String description;

    @ManyToMany(targetEntity = PollingSchedule.class, mappedBy = "polling", fetch = FetchType.EAGER)
    private List<PollingSchedule> variants;

    @Column(name = "start_time")
    private LocalDateTime startTime;

    @Column(name = "end_time")
    private LocalDateTime endTime;

    //getters and setters

@Entity
@Table(name = "polling_schedule")
public class PollingSchedule extends DomainIdObject {

    @JoinColumn(name = "polling_id")
    private Polling polling;

    @Column(name = "poll_var")
    private String pollingVariant;

    //gettters and setters

but when I execute the following code:

Query query = getEntityManager().createNativeQuery("SELECT * FROM polling p WHERE p.id=1", Polling.class);
List list = query.getResultList();
List<PollingSchedule> variants = ((Polling) list.get(0)).getVariants();

the variants list is empty. Tables in DB looks following:

polling
|id|owner_id|poll_name|description|start_time|end_time|

polling_schedule
|id|polling_id|poll_var|

So, in result I want that Polling object contains only those PollingVariants, that have corresponding polling_id in polling_schedule table.

I've try use Filter, SecondaryTable annotations, but it`s not work for me (or I was incorrect use it).

I use hibernate4 and spring boot 1.5.1

Could anyone help me?

Upvotes: 4

Views: 17889

Answers (1)

Drazen Nikolic
Drazen Nikolic

Reputation: 526

I think the relation between Polling and PollingSchedule is one-to-many (not many-to-many). And since you need a bidirectional relationship between those objects, you should change them like this:

Pooling.java

@Entity
@Table(name = "polling")
public class Polling extends DomainIdObject {
    ...
    @OneToMany(mappedBy="polling")
    private List<PollingSchedule> variants;
    ...
}

PoolingSchedule.java

@Entity
@Table(name = "polling_schedule")
public class PollingSchedule extends DomainIdObject {

    @ManyToOne
    @JoinColumn(name = "polling_id")
    private Polling polling;
    ...
}

Upvotes: 7

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