插入到JPA集合而不加载它
我目前正在使用这样的代码将新条目添加到我的实体中的集合中。
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，都会加载整套项目。
- 有没有办法（可能需要查询）添加该项目而不加载其余项目？在 SQL 中，它类似于
INSERT INTO AvatarAttributeOwnership(player, data, ...) VALUES({player}, ...); 当前唯一性由Set和AvatarAttributeOwnership.equals，但我认为这不再起作用。我怎样才能强制执行它？
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;
}
...
}
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.
- 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}, ...); Currently uniqueness is maintained by the contract ofSetandAvatarAttributeOwnership.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;
}
...
}
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尝试额外惰性集合：
Try extra-lazy collections: