Question

我正在尝试构建一个多语言数据库，因此我使用this database design作为我的方法。

现在我有两个问题/问题：

我想检索给定语言的所有LocalizedEvent并给出categoryId。如何使用Hibernate Criteria API在LocalizedCategory表上进行内连接？

使用SQL，我会将此语句用于获取所有LocalizedEvent + LocalizedCategory：

 SELECT * FROM event e
        INNER JOIN
    localized_event le ON (le.event_id = e.event_id)
        INNER JOIN
    localized_category lc ON (lc.category_id = e.category_id)
 WHERE
    le.locale = 'de' AND lc.locale = 'de'

我目前的方法看起来没有LocalizedCategory（使用Criteria API）：

Criteria c = session.createCriteria(LocalizedEvent.class, "localizedEvent");
c.createAlias("localizedEvent.event", "event");
c.createAlias("event.category", "category");
c.add(Restrictions.eq("category.categoryId", categoryId));
c.add(Restrictions.eq("localizedEvent.locale", language));

我认为我的映射不是100％正确。实体LocalizedEvent应该有一个属性localizedCategory，但我不想保存此localizedCategory的ID（因此我正在使用@Transient注释） LocalizedEvent表，例如使用ManyToOne关系（加入LOC_CATEGORY_ID）。但我认为不可能这样做，不是吗？我必须将这个瞬态字段映射到LocalizedEvent“手动”，因为Hibernate不支持这种映射（如果我是对的）。（使用JDBC这个属性/映射不会导致任何问题，因为我可以轻松地创建内部联接并将属性localizedCategory分配给RowMapper中的LocalizedEvent左右。）

我的实体看起来像这样：

事件

@Entity
@Table(name = "EVENT")
public class Event {
    @Id
    @GeneratedValue
    @Column(name = "EVENT_ID", unique = true)
    private Long eventId;

    @Column(name = "DATE")
    private Date date;

    @OneToMany(mappedBy = "event")
    private Set<LocalizedEvent> localizedEvents;

    @ManyToOne
    @JoinColumn(name = "CATEGORY_ID")
    private Category category;
}

LocalizedEvent

@Entity
@Table(name = "LOCALIZED_EVENT")
public class LocalizedEvent {
    @Id
    @GeneratedValue
    @Column(name = "LOC_EVENT_ID")
    private Long locEventId;

    @ManyToOne
    @JoinColumn(name = "EVENT_ID")
    private Event event;

    @Transient
    private LocalizedCategory localizedCategory;

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

    @Column(name = "LOCALE")
    private String locale;
}

分类

@Entity
@Table(name = "CATEGORY")
public class Category {
    @Id
    @GeneratedValue
    @Column(name = "CATEGORY_ID", unique = true)
    private Long categoryId;

    @OneToMany(mappedBy = "category")
    private Set<LocalizedCategory> localizedCategories;

    @OneToMany(mappedBy = "category")
    private Set<Event> events;
}

LocalizedCategory

@Entity
@Table(name = "LOCALIZED_CATEGORY")
public class LocalizedCategory {
    @Id
    @GeneratedValue
    @Column(name = "LOC_CATEGORY_ID")
    private Long locCategoryId;

    @ManyToOne
    @JoinColumn(name = "CATEGORY_ID")
    private Category category;

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

    @Column(name = "LOCALE")
    private String locale;
}

Hibernate - 多语言表

0 个答案: