Question

我试图填充List＆lt;＆gt;通过查询QueryDSL，但它会在bean填充时抛出错误。

这是我的方法;

@Override
    public Page<UserDTO> findByTypeQuerydsl(String filters, Pageable pageable) {
        JPAQuery query = new JPAQuery(entityManager);
        query = (JPAQuery) super.getQuerydsl().applyPagination(pageable, query);

        List<UserDTO> results = query.from(qUserDTO)
                  .innerJoin(qUser)
                  .on(qUserDTO.id.eq(qUser.id))
                  .where(qUserDTO.login.eq(filters))
                  .list(Projections.fields(UserDTO.class, qUser.id, qUser.login, qUser.firstname, qUser.lastname, qUser.dayofbirth, 
                          qUserDTO.district, qUserDTO.city));


        return new PageImpl<UserDTO>(results, pageable, results.size());
    }

在.list处抛出错误并说;

方法列表（Projections.fields（UserDTO.class，qUser.id， qUser.login，qUser.firstname，qUser.lastname，qUser.dayofbirth， qUserDTO.district，qUserDTO.city））未定义类型QueryBase

我的 UserDTO.class;

@Entity
@Table(name="USERDTO")
@QueryEntity
public class UserDTO implements Serializable {

    private static final long serialVersionUID = -7860243025833384447L;

    @Id
    private Long id;
    private String login;
    private String firstname;
    private String lastname;
    private Date dayofbirth;
    private String city;
    private String district;
    @OneToOne(fetch=FetchType.LAZY,cascade=CascadeType.ALL)
    @JoinColumn(name="id")
    User user;

    //getters and setters

    }

com-querydsl ;

的版本

    <dependency>
        <groupId>com.querydsl</groupId>
        <artifactId>querydsl-apt</artifactId>
        <version>4.1.3</version>
    </dependency>
    <dependency>
        <groupId>com.querydsl</groupId>
        <artifactId>querydsl-jpa</artifactId>
        <version>4.1.3</version>
    </dependency>

Answer 1

如果您使用的是querydsl 4.x，则应使用fetch（）方法，这样：

QueryBase queryBase = new JPAQuery(qUserDTO)....
FetchableQueryBase fetchableQueryBase = (FetchableQueryBase) queryBase;
fetchableQueryBase.fetch();

如果你真的想维护你的synthax，你应该降级到3.x版本。

Here，发行说明。

Answer 2

我使用queryDSL 4和Java 8流解决了这个问题：

List<UserDTO> results = new JPAQueryFactory(entityManager)
                .select(qUser.id, qUser.login, qUser.firstname, qUser.lastname, qUser.dayofbirth, qUserDTO.district, qUserDTO.city)
                .from(qUserDTO)
                .innerJoin(qUserDTO.user(), qUser)
                .where(qUserDTO.login.like(filters))
                .fetch()
                .stream()
                .map(c -> new UserDTO(c.get(qUser.id), c.get(qUser.login), c.get(qUser.firstname), c.get(qUser.lastname), 
                        c.get(qUser.dayofbirth), c.get(qUserDTO.district), c.get(qUserDTO.city)))
                .collect(Collectors.toList());

Bean种群错误 - Querydsl

2 个答案: