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[英]Load ManyToOne Relation with Hibernate Envers - Eager/Lazy?
[英]Eager query in a lazy relation?
我有一个具有这种惰性关系的实体:
@Getter
@Entity
@Table(name = "entity")
@SequenceGenerator(name = "seq_entity", sequenceName = "seq_entity", allocationSize = 1)
@DynamicUpdate
public class Entity {
@Id
@Column(name = "id_entity")
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq_entity")
private Long id;
@Setter
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "id_relation1")
private Relation1 relation1;
@Setter
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "id_relation2")
private Relation2 relation2;
// ...
}
当我查询以加载其他关系时,我必须像这样指定它们:
return jpaQuery() .select(qEntity) .distinct() .from(qEntity) .innerJoin(qEntity.relation1).fetchJoin() .leftJoin(qEntity.relation2).fetchJoin() .fetch();
但是我想在不指定的情况下将它们加载到一个查询的左联接和内部联接中...有一种方法可以在一个查询的渴望模式下全部加载? 是否可以为一个查询FetchType.LAZY
?
我在想类似
return jpaQuery() .select(qEntity) .distinct() .from(qEntity) .fetchEager();
您可以为此使用实体图。 将会是这样的:
EntityGraph<Post> entityGraph = entityManager.createEntityGraph(YourEntity.class);
entityGraph.addAttributeNodes("relation1");
entityGraph.addAttributeNodes("relation2");
并在查询
TypedQuery<Post> typedQuery = entityManager.createQuery(criteriaQuery);
typedQuery.setHint("javax.persistence.loadgraph", entityGraph);
Post post = typedQuery.getSingleResult();
可以用命名实体图(在实体上)括起来
@NamedEntityGraph(
name = "entity-with-all-relations",
attributeNodes = {
@NamedAttributeNode("relation1"),
@NamedAttributeNode("relation2"),
},
因此重复使用了很多次。 为此,请使用EntityManager#getEntityGraph
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