Criteria query on child object list in hibernate

Question

I have an Entity class A with child class as pendingUsers like below.

A.java

@Entity
public class A implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;

@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(name = "PENDING", joinColumns = {@JoinColumn(name = "aId")}, inverseJoinColumns = {@JoinColumn(name = "userId")})
@Cascade(value = org.hibernate.annotations.CascadeType.ALL)
private Set<User> approvers = new HashSet<User>();

@Column(name = "active", nullable = false, columnDefinition = "varchar default 'Y'")
@org.hibernate.annotations.Type(type = "yes_no")
private boolean active = true;

@NotBlank
@Column(nullable = false, unique = true)
private String poNo;
}

User.java

public class User{
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  @Column
  private int id;

  @NotBlank(message = "User ID cannot be empty")
  @Column(unique = true, nullable = false, updatable = false)
  private String userId;
}

I want to retrieve all A objects which has given userId as one of the approver. How to write this with hibernate Criteria?

I wrote like below when I had one to one mapping.

createEntityCriteria()
.add(Restrictions.eq("approvers.userId", userId))
.add(Restrictions.eq("active", true)).list();

As we changed now to many to many mapping how to achieve this?

Answer 1

I am quite new to this, however I've used this method successfully with many entities in a project that I am working on.

I've had this functionality working with code similar to what you have mentioned above. However, in case that does not work, you can play around with a Join, as follows:

    createEntityCriteria()
       .createAlias("approvers", "apprs", JoinType.INNER_JOIN)
       .add(Restrictions.eq("apprs.userId", userId))
       .add(Restrictions.eq("active", true)).list();

INNER_JOIN will return only records that have an approver, LEFT_OUTER_JOIN will return all parent rows with the approver where available.

Use: org.hibernate.sql.JoinType

Hope this helps.