我正在使用 JPA 2.0、Hibernate 4.1.0.Final 和 MySQL 5.5.27。我想构建一个 JPA 查询,每行将返回两个实体,并且我想执行右外连接。这两个实体是:
@Entity
@Table(name = "user",
uniqueConstraints = { @UniqueConstraint(columnNames = { "USER_NAME" }) }
)
public class User implements Comparable<User>, Serializable
{
...
@Column(name = "first_name")
@NotNull
/* the first name of the User */
private String firstName;
和
@Entity
@Table(name="code_user",
uniqueConstraints = {
@UniqueConstraint(columnNames = { "CODE_ID", "USER_ID" }) }
)
public class CodeUser
{
@Id
@NotNull
@GeneratedValue(generator = "uuid-strategy")
@Column(name = "ID")
private String id;
@ManyToOne
@JoinColumn(name = "CODE_ID", nullable = false, updatable = true)
private Code code;
@ManyToOne
@JoinColumn(name = "USER_ID", nullable = false, updatable = true)
private User user;
到目前为止,这是我的 JPA,但问题是正在执行内部连接,并且每行只返回一个实体(用户对象)......
final CriteriaBuilder builder = m_entityManager.getCriteriaBuilder();
final CriteriaQuery<User> criteria = builder.createQuery(User.class);
final Root<User> user = criteria.from(User.class);
final Root<CodeUser> codeUser = criteria.from(CodeUser.class);
final Join<CodeUser, User> joinUser = codeUser.join(CodeUser_.user);
criteria.select(joinUser);
…
return criteria.where(builder.and(preds.toArray(new Predicate[preds.size()])));
如何执行外部联接以便返回所有用户并返回任何匹配的 CodeUser 记录?向我的用户实体添加额外的成员字段不是一个选项。