播放框架:继承按类型排序 [英] Play Framework: Inheritance sort by type

问题描述

在我的应用程序中，我有2个类:

In my Application, I have 2 Classes:

- Group
- Model

和一个基类Element.

我使用单表策略来保留这些模型. (strategy = InheritanceType.SINGLE_TABLE).因此，在我的表格中创建了列dtype.

I use the single table strategy to persist these models. (strategy = InheritanceType.SINGLE_TABLE). Thus a column dtypeis created in my table.

我现在正尝试根据此类型对页面进行排序:

I'm now trying to sort my pages based on this type:

find.where().disjunction()
                .add(Expr.ilike("name", "%" + filter + "%"))
                .orderBy("dtype asc, name asc," + sortBy + " " + order).findList()

但这会引发异常，找不到dtype.

But this throws an Exception, that dtype cannot be found.

如何根据类型排序?

谢谢！

推荐答案

样本基本模型如下:

package models.db;

import play.db.ebean.Model;

import javax.persistence.*;
import java.util.Date;

@Entity
@Table(name = "content")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "dtype", discriminatorType = DiscriminatorType.STRING)
@DiscriminatorValue("content")
public abstract class Content extends Model {

    @Id
    public Long id;

    @Column(name = "dtype", insertable = false, updatable = false)
    public String dtype;

    public static Finder<Long, Content> find = new Finder<>(Long.class, Content.class);

    public String title;
    public Date created = new Date();
    public Date modified = new Date();


}

然后您可以将其扩展为:

Then you can extend it like:

package models.db;

import javax.persistence.*;

@Entity
@DiscriminatorValue("news")
public class News extends Content {

    @Id
    public Long id;
    public static Finder<Long, News> find = new Finder<>(Long.class, News.class);

    public String newsSource;

}

或

package models.db;

import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
import javax.persistence.Id;
import java.util.Date;

@Entity
@DiscriminatorValue("post")
public class Post extends Content {

    @Id
    public Long id;
    public static Finder<Long, Post> find = new Finder<>(Long.class, Post.class);

    public Date publishDate;

}

因此，您可以通过以下方式选择所有内容:

So you can choose all contents via:

List<Content> contents = Content.find.where().orderBy("dtype ASC").findList();

当然，这些对象将只有共享字段:id，dtype，title，created和modified，用于获取(新闻)newsSource或(发布)publishDate您需要使用自己的查找器来获取这些对象，即使用 general 内容查询中的id值.

Of course these objects will have only shared fields: id, dtype, title, created and modified, for getting i.e. (News) newsSource or (Post) publishDate you need to get these objects with their own finders i.e. using id value from general Content query.

这篇关于播放框架:继承按类型排序的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！