java - 如何在 JPAQuery 中使用 INNER JOIN？

Question

我准确地说，我是一名法国学生，正在学习 Java 开发人员一年级。而且我很确定我的问题标题对于我想要做的事情来说甚至不正确。那么希望下面的解释会更清楚一些!

我正在使用 Spring Boot、Spring security、Hibernate、Spring Data、Spring MVC 和 Thymeleaf 开发一个小型多模块应用程序。

这里是my repo

我目前正在研究一种处理多条件请求的方法。我正在使用 Querydsl。

这是涉及的域部分:

母实体

@Entity
@Table(name="element")
@Inheritance(strategy = InheritanceType.JOINED)
@Getter
@Setter
@NoArgsConstructor
@ToString
@EqualsAndHashCode
public abstract class Element {

//----------ATTRIBUTES----------

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;
    @NotNull
    @Size(min=4,max=50)
    private String name;
    private LocalDateTime createDate;
    private LocalDateTime updateDate;
    @OneToMany/*(mappedBy = "element")*/
    @JoinColumn(name = "element_id")
    private List< Comment > comments;
//..

子实体

/**
 * Bean used to define a book or a document that contains one or many climbing areas
 */
@Entity
@Table(name="atlas")
@PrimaryKeyJoinColumn(name = "element_id")
@Getter
@Setter
@NoArgsConstructor
@ToString( exclude = {"areas" , "bookingRequests" , "user"})
public class Atlas extends Element {

//----------ATTRIBUTES----------

    @ManyToMany
    @JoinTable(
        name = "areas_in_atlases",
        joinColumns = { @JoinColumn(name = "atlas_id") },
        inverseJoinColumns = { @JoinColumn(name = "area_id") } )
    private List< Area > areas;
    private String scale;
    private String country;
    private String region;
    private String department;
    private boolean available;
    @ManyToOne
    @JoinColumn(name = "user_id")
    private User user;
    @OneToMany(mappedBy = "atlas", cascade = CascadeType.ALL)
    private List<BookingRequest> bookingRequests;
//..



/**
 * Bean used to define an area with one or many climbing crag
 */
@Entity
@Table(name="area")
@PrimaryKeyJoinColumn(name = "element_id")
@Getter
@Setter
@NoArgsConstructor
@ToString
@EqualsAndHashCode( callSuper = true )
public class Area extends Element {

//----------ATTRIBUTES----------

    @ManyToMany(mappedBy = "areas")
    private List< Atlas > atlases;
    private Atlas atlas;
    @OneToMany/*(mappedBy = "area", fetch = FetchType.LAZY)*/
    @JoinColumn(name = "area_id")
    private List< Crag > crags;
    private int approachDuration;
    private String locality;
    @OneToMany/*(mappedBy = "area", fetch = FetchType.LAZY)*/
    @JoinColumn(name = "area_id")
    private List< Parking > parking;
    private String rockType;
//..

我的多标准方法的第一部分正在工作(我猜不是很优雅......):

@Override
public Page<Atlas> searchAtlasByNameAndCountryAndRegionAndDepartment( int page, int size, String name, String country, String region, String department ){

    QAtlas qAtlas = QAtlas.atlas;

    ArrayList< Predicate > predicates = new ArrayList<>();

    List<Atlas> atlases;

    if( !name.equals( "" ) ){
        predicates.add( qAtlas.name.containsIgnoreCase(name) );
    }
    if( !country.equals( "" ) ){
        predicates.add( qAtlas.country.containsIgnoreCase(country) );
    }
    if( !region.equals( "" ) ){
        predicates.add( qAtlas.region.containsIgnoreCase(region) );
    }
    if( !department.equals( "" ) ){
        predicates.add( qAtlas.department.containsIgnoreCase(department) );
    }

    BooleanBuilder booleanBuilder = new BooleanBuilder();

    for ( Predicate predicate: predicates ) {
        booleanBuilder.and(predicate);
    }

    atlases = ( List< Atlas > ) getDaoFactory().getAtlasRepository().findAll( booleanBuilder );

    long total = ( long ) atlases.size( );

    return new PageImpl(atlases, PageRequest.of( page, size ), total );
}

但我坚持使用仅在 Atlas 中的字段(例如国家/地区)在区域中搜索的方法。

    @Override
    public Page< Area > searchAreaByNameAndCountryAndRegionAndDepartment( int page, int size, String name, String country, String region, String department ){

        QAtlas qAtlas = QAtlas.atlas;
        QArea qArea = QArea.area;

        final JPAQueryFactory queryFactory = new JPAQueryFactory(em);


        List<Area> areas = queryFactory.selectFrom(qArea)
                                   .innerJoin(qAtlas)
                                   .where(
                                           qArea.name.containsIgnoreCase(name),
                                           qAtlas.country.containsIgnoreCase(country),
                                           qAtlas.department.containsIgnoreCase(department),
                                           qAtlas.region.containsIgnoreCase(region)
                                   )
                                   .fetch();

        long total = ( long ) areas.size( );

        return new PageImpl(areas, PageRequest.of( page, size ), total );
    }

当前控制台显示:

ervlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: Invalid path: 'atlas.areas' [select area
from org.thibaut.wheretoclimb.model.entity.Area area
  inner join atlas.areas as area
where lower(area.name) like ?1 escape '!' and lower(atlas.country) like ?2 escape '!' and lower(atlas.department) like ?1 escape '!' and lower(atlas.region) like ?1 escape '!']] with root cause

org.hibernate.hql.internal.ast.QuerySyntaxException: Invalid path: 'atlas.areas' [select area
from org.thibaut.wheretoclimb.model.entity.Area area
  inner join atlas.areas as area
where lower(area.name) like ?1 escape '!' and lower(atlas.country) like ?2 escape '!' and lower(atlas.department) like ?1 escape '!' and lower(atlas.region) like ?1 escape '!']

有人可以帮我解决这个问题吗？

非常感谢你们抽出宝贵的时间!

Answer 1

解决方案:

public Page< Area > searchAreaByNameAndCountryAndRegionAndDepartment( int page, int size, String name, String country, String region, String department ){

        QAtlas qAtlas = QAtlas.atlas;
        QArea qArea = QArea.area;

        JPAQueryFactory queryFactory = new JPAQueryFactory(em);

        BooleanBuilder booleanBuilder = new BooleanBuilder();

        if( ! name.equals( "" ) ){
            booleanBuilder.and( qArea.name.containsIgnoreCase(name) );
        }
        if( ! country.equals( "" ) ){
            booleanBuilder.and( qAtlas.country.containsIgnoreCase(country) );
        }
        if( ! region.equals( "" ) ){
            booleanBuilder.and( qAtlas.region.containsIgnoreCase(region) );
        }
        if( ! department.equals( "" ) ){
            booleanBuilder.and( qAtlas.department.containsIgnoreCase(department) );
        }

        List<Area> areas = queryFactory.from(qAtlas)
                                   .innerJoin(qAtlas.areas, qArea)
                                   .where(booleanBuilder)
                                   .select(qArea)
                                   .fetch();

        long total = ( long ) areas.size( );

        return new PageImpl(areas, PageRequest.of( page, size ), total );
    }

非常感谢你们抽出宝贵的时间!