【问题标题】:MyBatis @Many / Spring-BootMyBatis @Many / Spring-Boot
【发布时间】:2019-08-06 10:32:11
【问题描述】:

我是初学者(对不起,我的解释不好,请随时纠正我)在 MyBatis Spring-Boot 中,我有问题要理解并使其工作@Many

我正在使用 3 层逻辑编程(表示层、服务层、数据层)

感谢您的帮助:)

我有 3 个表(屏幕截图中是 TB_Products 而不是 TB_Product):

我想获取数据表 TB_Users 和 TB_Products 以将其“放入”DTO

  • 我创建4个java对象类SearchEntity、ProductEntity(用于数据层)

  • 我创建了一个接口 SearchRepositoryMapper。

  • 我还创建了一个 SearchService 接口和 SearchServiceImpl。

Java 对象类:

搜索实体

public class SearchEntity implements Serializable{

    private static final long serialVersionUID = -9143930742617602050L;

    private String id;
    private String firstName;
    private String lastName;
    private List<ProductEntity> products;


                       // Getters and Setters code .....

}

产品实体

public class ProductEntity implements Serializable{

    private static final long serialVersionUID = -6525703679290992635L;

    private String id;
    private String productId;
    private String product;
    private String number;
    private String date;
    private String description;


                       // Getters and Setters code .....
}

SearchRepositoryMapper

public interface SearchRepositoryMapper {

    // Get some fields from TB_Users and all fields from TB_Products 
    @Select("SELECT * FROM TB_Users WHERE id = #{id}")
    @Results({
            @Result(property = "id", column ="id"),
            @Result(property = "firstName", column = "firstName"),
            @Result(property = "lastName", column= "lastName"),
            @Result(property = "products", javaType = List.class, column="id",
                    many = @Many(select = "getProductIdByUserId"))})
    public SearchEntity findAllInfoByUserId(@Param("id") int id);


    @Select("SELECT *, productId FROM TB_Products WHERE productId = #{id}")
    public ArrayList<ProductEntity> getProductIdByUserId(@Param("id") int id);



    // Find id by uderId and return null if it doesn't exist
    @Select("SELECT id FROM TB_Users WHERE userId = #{userId}")
    int findIdByUserId(@Param("userId") String userId);
}

SearchServiceImpl

@Service
public class SearchServiceImpl implements SearchService {

    @Autowired
    SearchRepositoryMapper searchRepository;

    @Override
    public SearchDto getAllInfoByUserId(String id) {

        SearchDto returnValue = new SearchDto();                                // Init returnValue as SearchDto
        int searchId = searchRepository.findIdByUserId(id);                             // Init searchId with the TB_Users id


        SearchEntity searchEntity = searchRepository.findAllInfoByUserId(searchId);

        BeanUtils.copyProperties(searchEntity, returnValue);

        return returnValue;
    }

}

因此,当我执行代码并执行 GET 请求时,我会收到以下错误消息:

{
    "message": "nested exception is org.apache.ibatis.executor.ExecutorException: Statement returned more than one row, where no more than one was expected."
}

我发现来自映射器和SearchEntity searchEntity = searchRepository.findAllInfoByUserId(searchId);

但我不知道如何解决它。我写代码的方式不对

谢谢指正

【问题讨论】:

    标签: spring-boot mybatis spring-mybatis


    【解决方案1】:

    异常清楚地表明查询返回多个结果。请验证表中数据是否正确。

    【讨论】:

    • 好吧,我发现了。首先最好使用 List 而不是 ArrayList。其次,最好使用正确的导入列表,即 java.util.List。正如你所说,为值使用正确的类型......谢谢Sereysopheak Eap! :)