QueryDSL 和多对多关系

Question

在一个项目中，我有以下实体：具有连接到关键字的模板部分的模板。这两个关系都是@ManyToMany。一些代码：

@NoArgsConstructor
@Getter
@Setter
@Entity
@Table(name = "TEMPLATE")
public class TemplateEntity extends SystemFlagEntity {

    ...

    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(
            name = "TEMPLATEPART_CATALOGUE",
            joinColumns = @JoinColumn(name = "C_FK_TEMPLATE", referencedColumnName = "C_I_IDF"),
            inverseJoinColumns = @JoinColumn(name = "C_FK_TEMPLATEPART", referencedColumnName = "C_I_IDF"))
    Set<TemplatePartEntity> templatePartsCatalogue = new HashSet<>();

}

@ToString
@NoArgsConstructor
@Getter
@Setter
@Entity
@Table(name = "TEMPLATEPART")
public class TemplatePartEntity extends SystemFlagEntity {

    ...

    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(
            name = "TEMPLATEPART_KEYWORD",
            joinColumns = @JoinColumn(name = "C_FK_TEMPLATEPART"),
            inverseJoinColumns = @JoinColumn(name = "C_FK_KEYWORD"))
    Set<KeywordEntity> keywords = new HashSet<>();

}

@NoArgsConstructor
@Getter
@Setter
@Entity
@Table(name = "KEYWORD")
public class KeywordEntity extends LabeledEntity {

    ...

}

然后我尝试查找与具有给定 ID 的某个模板相关的关键字。我用 QueryDSL 使用这个谓词来做到这一点：

public Iterable<KeywordEntity> findCatalogueKeywordsForTemplate(Long id) {
    return findAll(
        QKeywordEntity.keywordEntity.in(QTemplateEntity.templateEntity.templatePartsCatalogue.any().keywords)
            .and(QTemplateEntity.templateEntity.id.eq(id))
    );
}

由于某种原因，谓词根本无法很好地处理。尝试调用方法时出现此错误：

org.hibernate.hql.internal.ast.QuerySyntaxException: templateEntity.templatePartsCatalogue is not mapped [select keywordEntity\nfrom mypackage.core.domain.model.KeywordEntity keywordEntity\nwhere exists (select 1\nfrom templateEntity.templatePartsCatalogue as templateEntity_templatePartsCatalogue_0\nwhere keywordEntity member of templateEntity_templatePartsCatalogue_0.keywords) and templateEntity.id = ?1]; nested exception is java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: templateEntity.templatePartsCatalogue is not mapped [select keywordEntity\nfrom mypackage.core.domain.model.KeywordEntity keywordEntity\nwhere exists (select 1\nfrom templateEntity.templatePartsCatalogue as templateEntity_templatePartsCatalogue_0\nwhere keywordEntity member of templateEntity_templatePartsCatalogue_0.keywords) and templateEntity.id = ?1]

它似乎没有很好地处理 @ManyToMany 关联。关于如何解决此问题的任何想法？我知道我可以明确地使用 JPAQuery，但我想改用 Predicate。

Answer 1

看到 QueryDSL's creator 的回答后，我发现我误解了谓词的工作方式。此查询无需显式定义多对多关联表即可工作：

public Iterable<KeywordEntity> findCatalogueKeywordsForTemplate(Long id) {
    return new JPAQuery<>(entityManager)
            .select(QKeywordEntity.keywordEntity)
            .from(QTemplateEntity.templateEntity)
            .innerJoin(QTemplateEntity.templateEntity.templatePartsCatalogue, QTemplatePartEntity.templatePartEntity)
            .innerJoin(QTemplatePartEntity.templatePartEntity.keywords, QKeywordEntity.keywordEntity)
            .where(interceptPredicate(QTemplateEntity.templateEntity.id.eq(id)))
            .distinct()
            .fetch();
}

QueryDSL 和多对多关系

QueryDSL and ManyToMany relationships

hibernate

jpa

many-to-many

querydsl

predicate