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, MyEntityRepositoryCustom {

}

public interface MyEntityRepositoryCustom {

    List findAllByUserId(String userId);

}

public class MyEntityRepositoryImpl implements MyEntityRepositoryCustom {

    @PersistenceContext
    private EntityManager em;

    @Override
    public List 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!