Spring Data JPA-如何将查询结果转换为实体类 [英] Spring Data JPA - How to convert Query result to entity class

问题描述

我在Spring Boot应用程序中使用Spring Data JPA.我有一个几乎没有属性的实体类.考虑到我有10个与实体User关联的属性，我只想检索其中的几个属性(用户名，密码，名字，姓氏，电子邮件).

Am using Spring Data JPA with spring boot application. I have an entity class with few properties. Consider I have 10 properties associated with the entity User and I want to retrieve only few of them (username,password,firstname,lastname,email).

因此，我编写了一个查询，仅获取5个字段，但是该方法不返回实体对象，而是返回一个普通对象.

So I have wrote a query to get the 5 fields only, but the method does not return entity object, instead it returns a plain object.

如何将查询结果转换为Spring Data JPA中的实体?

How can I cast the query result to entity in Spring Data JPA ?

@Query("select userName,password,firstName,lastName,email from User")
public List<User> getUsers();

推荐答案

您必须创建一个结果类，然后稍稍更改查询:

You have to create a result class and then change the query a bit:

package com.example;

public class ResultClass{

    String userName,password,firstName,lastName,email;

    public ResultClass(String userName, String password
          , String firstName, String lastName, String email){
         // set fields;
    }
}

并查询:

@Query("select new com.example.ResultClass(userName,password
              ,firstName,lastName,email) from User")
public List<ResultClass> getUsers();

选择顺序必须与构造函数顺序匹配.

The order of selection must match the constructor ordering.

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