Querydsl在多个Collection级别中引发“参数类型不匹配”

Question

我有一个数据库结构，其中包含三个对象表和两个“多对多连接”表来连接它们。结果是一个三级对象模型。

公司<->员工<->电子邮件

当我像这样对数据库执行查询时：

List <CompanyDTO> companies = new JPAQueryFactory(entityManager)
                .from(COMPANY)
                .leftJoin(COMPANY.employee, COMPANY_EMPLOYEE)
                .leftJoin(COMPANY_EMPLOYEE.email, COMPANY_EMPLOYEE_EMAIL)
                .transform(groupBy(COMPANY.id).list(
                        new QCompanyDTO(
                                COMPANY.id,
                                set(new QEmployeeDTO(
                                        COMPANY_EMPLOYEE.id,
                                        set(new QEmailDTO(
                                                COMPANY_EMPLOYEE_EMAIL.id,
                                                COMPANY_EMPLOYEE_EMAIL.email,
                                                COMPANY_EMPLOYEE_EMAIL.type
                                        ))
                                ))
                        )));

Querydsl在初始化对象时遇到问题。 由于构造函数用法错误，初始化EmailDTO对象时会发生问题。

春季启动版本：v2.1.5.RELEASE Querydsl版本：4.2.1

有没有办法使它工作？

Caused by: java.lang.IllegalArgumentException: argument type mismatch
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_192]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_192]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_192]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_192]
    at com.querydsl.core.types.ConstructorExpression.newInstance(ConstructorExpression.java:141) ~[querydsl-core-4.2.1.jar:na]
    at com.querydsl.core.types.FactoryExpressionUtils.compress(FactoryExpressionUtils.java:155) ~[querydsl-core-4.2.1.jar:na]
    at com.querydsl.core.types.FactoryExpressionUtils.access$100(FactoryExpressionUtils.java:28) ~[querydsl-core-4.2.1.jar:na]
    at com.querydsl.core.types.FactoryExpressionUtils$FactoryExpressionAdapter.newInstance(FactoryExpressionUtils.java:62) ~[querydsl-core-4.2.1.jar:na]
    at com.querydsl.core.types.FactoryExpressionUtils$FactoryExpressionAdapter.newInstance(FactoryExpressionUtils.java:62) ~[querydsl-core-4.2.1.jar:na]
    at com.querydsl.jpa.TransformingIterator.next(TransformingIterator.java:63) ~[querydsl-jpa-4.2.1.jar:na]
    at com.querydsl.core.group.GroupByList.transform(GroupByList.java:60) ~[querydsl-core-4.2.1.jar:na]
    at com.querydsl.core.group.GroupByList.transform(GroupByList.java:36) ~[querydsl-core-4.2.1.jar:na]
    at com.querydsl.core.support.FetchableQueryBase.transform(FetchableQueryBase.java:55) ~[querydsl-core-4.2.1.jar:na]

import com.querydsl.core.annotations.QueryProjection;

public class EmailDTO {

    private Long id;


    private String mail;
    private String type;

    @QueryProjection
    public EmailDTO (Long id, String mail, String type) {
        this.id = id;
        this.mail = mail;
        this.type = type;
    }

    public Long getId () {
        return id;
    }

    public void setId (Long id) {
        this.id = id;
    }

    public String getMail () {
        return mail;
    }

    public void setMail (String mail) {
        this.mail = mail;
    }

    public String getType () {
        return type;
    }

    public void setType (String type) {
        this.type = type;
    }

    @Override
    public String toString () {
        return "{\"email\":{"
               + "\"id\":\"" + id + "\""
               + ", \"mail\":\"" + mail + "\""
               + ", \"type\":\"" + type + "\""
               + "}}";
    }
}

import com.querydsl.core.annotations.QueryProjection;

import java.util.List;

public class EmployeeDTO {

    private Long id;

    private List <EmailDTO> emails;

    @QueryProjection
    public EmployeeDTO (Long id, List <EmailDTO> emails) {
        this.id = id;
        this.emails = emails;
    }

    public Long getId () {
        return id;
    }

    public void setId (Long id) {
        this.id = id;
    }

    public List <EmailDTO> getEmails () {
        return emails;
    }

    public void setEmails (List <EmailDTO> emails) {
        this.emails = emails;
    }

    @Override
    public String toString () {
        return "{\"employee\":{"
               + "\"emails\":" + emails
               + ", \"id\":\"" + id + "\""
               + "}}";
    }
}

import com.querydsl.core.annotations.QueryProjection;

import java.util.List;

public class CompanyDTO {

    private Long               id;
    private List <EmployeeDTO> employees;


    @QueryProjection
    public CompanyDTO (Long id, List <EmployeeDTO> employees) {
        this.id = id;
        this.employees = employees;
    }

    public Long getId () {
        return id;
    }

    public void setId (Long id) {
        this.id = id;
    }

    public List <EmployeeDTO> getPipes () {
        return employees;
    }

    public void setPipes (List <EmployeeDTO> employees) {
        this.employees = employees;
    }

    @Override
    public String toString () {
        return "{\"Company\":{"
               + "\"id\":\"" + id + "\""
               + ", \"employees\":" + employees
               + "}}";
    }
}