外键查询播放！框架2. + ebean [英] foreign key query play! framework 2.+ ebean

问题描述

我是新来玩框架和Ebean ORM的人.

I'm new to play framework and the Ebean ORM.

基本上，我有两个模型，一个是RegUsers，另一个是RegIds.在我的注册ID中，我在字段RegUsers上建立了多对一关系.声明，如果我没记错的话，一个用户可以有许多注册ID.

Basically, I have two models one is a RegUsers the other is RegIds. In my registration Ids I put a many to one relationship on the Field RegUsers. Stating, if I'm not mistaken that one user can have many registration ids.

RegId型号:

@Entity 
public class RegId extends Model{
    public static Finder<Long,RegId> finder = new Finder<Long,RegId>(Long.class, RegId.class);

    @Id
    public Long id;

    @ManyToOne
    public RegUsers regUsers;

    public String regId;
}

RegUser型号:

@Entity 
public class RegUsers extends Model{

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

    @Id
    public Long id;

    public String email;
    public String name;
}

RegId必须具有RegUser，但是RegUser不需要具有RegId. 对于我的一种观点，我试图向所有仅拥有一次RegId的RegUsers展示，但无法弄清楚该怎么做.

A RegId must have a RegUser, but a RegUser does not need to have a RegId. For one of my views I'm trying to show all RegUsers who do have an RegId only once, but cannot figure out how to do this.

我很像这样查询RegId表:

List<RegId> reg = RegId.finder.where().findList();

然后通过以下方式查询RegUser.name:

And then querying the RegUser.name by:

@(regs: List[RegId])

@for(reg <- regs){
    <p>@reg.regUsers.email</p>
}

但是我不知道如何只显示不同的记录.有没有办法使用Ebean做到这一点，或者我需要写原始sql吗?我将不胜感激任何帮助.

But I can't figure out how to only show distinct records. Is there a way to do this using Ebean or will I need to writ raw sql? I would appreciate any help.

推荐答案

如果您向RegUsers定义中添加regIds字段，如下所示:

if you add a regIds field to your RegUsers definition like this:

@Entity 
public class RegUsers extends Model{

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

    @Id
    public Long id;

    public String email;
    public String name;

    @OneToMany(mappedBy="regUsers")
    public Set<RegId> regIds;
}

您可以查询具有至少个 RegId的RegUsers，如下所示:

you can query for RegUsers that have at least one RegId like this:

RegUsers.find.where().isNotNull("regIds.id").findList()

如果要查找与完全相同的 RegId的RegUsers，则确实需要编写自定义sql.

if you want to find RegUsers with exactly one RegId then you need to write custom sql indeed.

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