插入JPA集合而不加载它 [英] Insert to JPA collection without loading it

问题描述

我目前正在使用这样的代码为我的实体中的集合添加一个新条目。

  player = em .find（Player.class，playerId）; 
 player.getAvatarAttributeOwnership（）。add（new AvatarAttributeOwnership（...））; 
  

它可以工作，但每次我想添加一个项目时，整个集合都会被加载。 p>

1. 有没有一种方法（可能有查询）添加项目而不加载其余项目？在SQL中，它可能类似于 INSERT INTO AvatarAttributeOwnership（player，data，...）VALUES（{player}，...）;


2. 目前唯一性由 Set 和 AvatarAttributeOwnership.equals 的合约维护，但我假设那将不再有效。我该如何执行它？
我使用JPA2 + Hibernate。代码：

  @Entity 
公共类Player实现Serializable {
 
 @Id 
 @GeneratedValue 
私人长ID; 
 
 @ElementCollection（fetch = FetchType.LAZY）
 //编辑：＃2 
 @CollectionTable（uniqueConstraints = @ UniqueConstraint（columnNames = {Player_id，gender ，type，attrId}））
 Set< AvatarAttributeOwnership> ownedAvatarAttributes; 
 
 ... 
 
} 
 
 @Embeddable 
 public class AvatarAttributeOwnership实现Serializable {
 
 @Column （nullable = false，长度= 6）
 @Enumerated（EnumType.STRING）
私人性别性别; 
 
 @Column（nullable = false，长度= 20）
私有字符串类型; 
 
 @Column（nullable = false，length = 50）
 private String attrId; 
 
 @Column（nullable = false）
私有日期自; 
 
 @Override 
 public boolean equals（Object obj）{
 
 if（this == obj）return true; 
 if（obj == null）return false; 
 if（getClass（）！= obj.getClass（））返回false; 
 
 AvatarAttributeOwnership other =（AvatarAttributeOwnership）obj; 
 
 if（！attrId.equals（other.attrId））return false; 
 if（gender！= other.gender）返回false; 
 if（！type.equals（other.type））返回false; 
 
返回true; 
} 
 
 ... 
 
} 
  




解决方案

请尝试额外-lazy collection ：
$ b $ pre $ @LazyCollection（LazyCollectionOption.EXTRA）





I'm currently using code like this to add a new entry to a set in my entity.

player = em.find(Player.class, playerId);
player.getAvatarAttributeOwnership().add(new AvatarAttributeOwnership(...));

It works, but every time I want to add one item, the whole set is loaded.

1. Is there a way (with a query maybe) to add the item without loading the rest? In SQL it would be something like INSERT INTO AvatarAttributeOwnership(player, data, ...) VALUES({player}, ...);
2. Currently uniqueness is maintained by the contract of Set and AvatarAttributeOwnership.equals, but I assume that won't work anymore. How can I enforce it anyway?

I'm using JPA2+Hibernate. Code:

@Entity
public class Player implements Serializable {

    @Id
    @GeneratedValue
    private long id;

    @ElementCollection(fetch=FetchType.LAZY)
    // EDIT: answer to #2
    @CollectionTable(uniqueConstraints=@UniqueConstraint(columnNames={"Player_id","gender","type","attrId"}))
    Set<AvatarAttributeOwnership> ownedAvatarAttributes;

    ...

}

@Embeddable
public class AvatarAttributeOwnership implements Serializable {

    @Column(nullable=false,length=6)
    @Enumerated(EnumType.STRING)
    private Gender gender;

    @Column(nullable=false,length=20)
    private String type;

    @Column(nullable=false,length=50)
    private String attrId;

    @Column(nullable=false)
    private Date since;

    @Override
    public boolean equals(Object obj) {

        if (this == obj) return true;
        if (obj == null) return false;
        if (getClass() != obj.getClass()) return false;

        AvatarAttributeOwnership other = (AvatarAttributeOwnership) obj;

        if (!attrId.equals(other.attrId)) return false;
        if (gender != other.gender) return false;
        if (!type.equals(other.type)) return false;

        return true;
    }

    ...

}

解决方案

Try extra-lazy collections:

@LazyCollection(LazyCollectionOption.EXTRA)

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