MyBatis @许多/ Spring-Boot

Question

我是初学者（抱歉，我的错误解释，请随时纠正我）在MyBatis Spring-Boot中，我很难理解并使其适用于@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（如屏幕截图所示是TB_Products，而不是TB_Product）：

我想获取表格TB_Users和TB_Products的数据以将其“放入” DTO

• 我创建4个Java对象类SearchEntity，ProductEntity（用于数据层）

• 我创建一个接口SearchRepositoryMapper。

• 我还创建了SearchService接口和SearchServiceImpl。

Java对象类：

SearchEntity

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 .....

}

ProductEntity

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，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."
}

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

但是我不知道如何解决它。我编写代码的方式是错误的

感谢纠正我

Answer 1

该异常清楚地表明查询返回了多个结果。请验证表中的数据是否正确。