How to query on subset of composite primary key?

Question

I have the following classes:

@Entity
@Table(name = \"my_entity\")
@JsonIgnoreProperties(ignoreUnknown = true)
public class MyEntity {
    @EmbeddedId
    pr         


        

Answer 1

Okay, I also tried doing this with @IdClass instead:

@Entity
@Table(name = "my_entity")
@JsonIgnoreProperties(ignoreUnknown = true)
@IdClass(Pk.class)
public class MyEntity {
    @Id private Integer type;
    @Id private String userId;

    public Pk getId() {
        return id;
    }

    public void setId(Pk id) {
        this.id = id;
    }

}

@IdClass(Pk.class)
public class Pk implements Serializable {
    private static final long serialVersionUID = -3090221844117493661L;
    private Integer type;
    private String userId;

    public Pk() {
    }

    public Pk(String userId, Integer type) {
        this.setUserId(userId);
        this.setType(type);
    }

    public Integer getType() {
        return type;
    }

    public String getUserId() {
        return userId;
    }

    public void setType(Integer type) {
        this.type = type;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    // Auto-generated by Eclipse.
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((type == null) ? 0 : type.hashCode());
        result = prime * result + ((userId == null) ? 0 : userId.hashCode());
        return result;
    }

    // Auto-generated by Eclipse.
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Pk other = (Pk) obj;
        if (type != other.type)
            return false;
        if (userId == null) {
            if (other.userId != null)
                return false;
        } else if (!userId.equals(other.userId))
            return false;
        return true;
    }

}

This did gave me a different error message, a NullPointerException, that was hinting to me that Spring Data JPA was unable to build the query for findAllByUserId(...). I made a custom implementation of that query method instead:

public interface MyEntityRepository extends JpaRepository<MyEntity, Pk>, MyEntityRepositoryCustom {

}

public interface MyEntityRepositoryCustom {

    List<MyEntity> findAllByUserId(String userId);

}

public class MyEntityRepositoryImpl implements MyEntityRepositoryCustom {

    @PersistenceContext
    private EntityManager em;

    @Override
    public List<MyEntityRepositoryCustom> findAllByUserId(String userId) {
        return em
                .createQuery("select o from MyEntity o where o.userId=:userId",
                        MyEntity.class).setParameter("userId", userId).getResultList();
    }

}

...and voilá, it works!

Answer 2

You need to tell JPA where to look for the userId field (in the embedded id, that is). If you change the name of the repository method to findAllByIdUserId, it should work.