Question

我目前正在使用这样的代码向我的实体中的一个集添加新条目。

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

它有效，但每次我想添加一个项目时，都会加载整个集合。

是否有办法（可能有查询）添加项目而不加载其余项目？在SQL中，它将类似于INSERT INTO AvatarAttributeOwnership(player, data, ...) VALUES({player}, ...);
~~目前唯一性由Set和AvatarAttributeOwnership.equals的合同维护，但我认为这将不再适用。我怎么能强制执行呢？~~

我正在使用JPA2 + Hibernate。代码：

@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;
    }

    ...

}

Answer 1

尝试extra-lazy collections：

@LazyCollection(LazyCollectionOption.EXTRA)

插入JPA集合而不加载它

1 个答案: