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如何使用謂詞BooleanExpression在多對多關係上完成內部連接？如何在QueryDSL中爲多對多關係創建謂詞BooleanExpression
我有2個實體
public class A {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
@ManyToMany(fetch = FetchType.LAZY,
cascade = { CascadeType.DETACH, CascadeType.MERGE,
CascadeType.REFRESH, CascadeType.PERSIST})
@JoinTable(name = "a_b_maps",
joinColumns = @JoinColumn(name = "a_id", nullable =
false,referencedColumnName = "id"),
inverseJoinColumns = @JoinColumn(name = "b_id", nullable = false,
referencedColumnName = "id")
)
private Set<B> listOfB = new HashSet<B>();
}
public class B {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
@ManyToMany(fetch = FetchType.LAZY,
cascade = { CascadeType.DETACH, CascadeType.MERGE,
CascadeType.REFRESH, CascadeType.PERSIST})
@JoinTable(name = "a_b_maps",
joinColumns = @JoinColumn(name = "b_id", nullable =
false,referencedColumnName = "id"),
inverseJoinColumns = @JoinColumn(name = "a_id", nullable = false,
referencedColumnName = "id")
)
private Set<A> listOfA = new HashSet<A>();
}
一個基地回購
@NoRepositoryBean
public interface BaseRepository<E, I extends Serializable>
extends JpaRepository<E, I> {
}
而且存儲庫類的一個
public interface Arepo extends BaseRepository<A, Integer>,
QueryDslPredicateExecutor<A> {
Page<A> findAll(Predicate predicate, Pageable pageRequest);
}
現在我想使用謂詞查詢回購。我需要形成一個謂語在那裏我可以加載基於一些定BS
我試圖
QA a = QA.a;
QB b = QB.b;
BooleanExpression boolQuery = null;
JPQLQuery<A> query = new JPAQuery<A>();
query.from(a).innerJoin(a.listOfB, b)
.where(b.id.in(someList));
現在我能夠形成JPQLQuery，但庫需要一個謂語。我怎樣才能從JPQLQuery Predicate？
或者，如何使用Predicate實現內部連接？