Play Framework - 如何从超类继承？ [英] Play Framework - How to inherit from superclass?

问题描述

我有一个扩展Model的User类，以及我想扩展User类的两个类。

I have a User class, which extends Model, and two classes that I want to extend the User class.

User.java：

@Entity
@Table(name = "users")
public class User extends Model implements RoleHolder {

    private static final long serialVersionUID = 1L;

    @Id
    public Long id;

...

Driver.java：

public class Driver extends User {
...

Customer.java：

public class Customer extends User {
...

编辑
所有三个实体都需要直接访问。换句话说，我有用户，客户和司机;客户和驱动程序碰巧共享用户的所有属性。因此，我需要有一个有效的用户实体以及客户和驱动程序。

Edit All three entities need to be directly accessed. To say it another way, I have Users, Customers, and Drivers; Customers and Drivers just happen to share all of the properties of a User. Therefore, I need to have a valid User entity as well as Customer and Driver.

我需要能够获得所有用户（包括客户和驱动程序）的列表。

I need to be able to get a list of all Users (including Customers and Drivers).

我无法弄清楚如何在Play中使用 ebean 来完成这项工作。我怎样才能做到这一点？

I haven't been able to figure out how to make this work using ebean in Play. How can I do this?

推荐答案

为了保持用户表的具体，您可以使用 @Inheritance 注释。有关讨论，请参见 Play Framework 2 Ebean和InheritanceType为JOINED 关于那个。

To keep the User table concrete, you can use the @Inheritance annotation. See Play Framework 2 Ebean and InheritanceType as JOINED for a discussion about that.

也可以使用 @OneToOne 为司机和客户手动加入辅助表。

Also possible is to manually join auxiliar tables for Drivers and Customers using @OneToOne.

使用 @OneToOne 也有利于作品优于继承，这被认为是一种很好的做法。

Using @OneToOne would also be favor composition over inheritance, which is considered a good practice.

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