Mybatis mapper 返回空值。在春天-rest-mybatis-mysql-gradle答案

【问题标题】：Mybatis mapper returns null value. in spring -rest-mybatis-mysql-gradleMybatis mapper 返回空值。在春天-rest-mybatis-mysql-gradle
【发布时间】：2020-08-08 05:22:01
【问题描述】：

{ “代码”：1000， “消息”：“成功”， “时间戳”：1596860735157， “数据”： [ { “身份证”：1， “内容名称”：空， “创建时间”：0， “内容路径”：空 }, { “身份证”：2， “内容名称”：空， “创建时间”：0， “内容路径”：空 }, { “身份证”：3， “内容名称”：空， “创建时间”：0， “内容路径”：空 } ] }

在 t_content_library=> id:bigint,content_name:varchar(450),content_path:varchar(500),created_time:bigint。

mysql> select * from t_content_library;
+----+----------------------------------------------------+----------------------------------------------------------------------------------+---------------+
| id | content_name                                       | content_path                                                                     | created_time  |
+----+----------------------------------------------------+----------------------------------------------------------------------------------+---------------+
|  1 | pexels-jack-redgate-3014019.jpg                    | C:\Users\DELL\Desktop\content\pexels-jack-redgate-3014019.jpg                    | 1596783953545 |
|  2 | pexels-thiago-matos-2335275.jpg                    | C:\Users\DELL\Desktop\content\pexels-thiago-matos-2335275.jpg                    | 1596784207089 |
|  3 | louis-hansel-shotsoflouis-2gwghEzGp4g-unsplash.jpg | C:\Users\DELL\Desktop\content\louis-hansel-shotsoflouis-2gwghEzGp4g-unsplash.jpg | 1596784491699 |
|  4 | jessica-delp-p1P_e86R2DI-unsplash.jpg              | C:\Users\DELL\Desktop\content\jessica-delp-p1P_e86R2DI-unsplash.jpg              | 1596784579313 |
|  5 | patrick-untersee-OrT5-yC95j0-unsplash.jpg          | C:\Users\DELL\Desktop\content\patrick-untersee-OrT5-yC95j0-unsplash.jpg          | 1596784602268 |
|  6 | jun-zhao-XWQ15ixxRjE-unsplash.jpg                  | C:\Users\DELL\Desktop\content\jun-zhao-XWQ15ixxRjE-unsplash.jpg                  | 1596784616456 |
|  7 | jo-jo-mPM-x0zPhok-unsplash.jpg                     | C:\Users\DELL\Desktop\content\jo-jo-mPM-x0zPhok-unsplash.jpg                     | 1596784632238 |
|  8 | melnychuk-nataliya-8J6uuvsdj-4-unsplash.jpg        | C:\Users\DELL\Desktop\content\melnychuk-nataliya-8J6uuvsdj-4-unsplash.jpg        | 1596784644961 |
|  9 | nathan-anderson-UhagOo7IOyc-unsplash.jpg           | C:\Users\DELL\Desktop\content\nathan-anderson-UhagOo7IOyc-unsplash.jpg           | 1596784877626 |
| 10 | gayathri-sri-ptbKY_b1ROc-unsplash.jpg              | C:\Users\DELL\Desktop\content\gayathri-sri-ptbKY_b1ROc-unsplash.jpg              | 1596784887985 |
| 11 | Depositphotos_95439918_xl-2015_1920x1920.jpg       | C:\Users\DELL\Desktop\content\Depositphotos_95439918_xl-2015_1920x1920.jpg       | 1596907309367 |
+----+----------------------------------------------------+----------------------------------------------------------------------------------+---------------+

型号

 @Data
 @AllArgsConstructor
 @NoArgsConstructor
 @Builder
 @ToString
 public class ContentLibrary {
   int id;
   String contentName;
   long createdTime;
   String contentPath;

 }

控制器

 @RequestMapping(path = "content/library/")
 @RestController
 public class ContentLibraryController {
 @Autowired
 ContentLibraryService contentLibraryService;

 @PostMapping("")
 public Response readLibrary() {
 List<ContentLibrary> contentLibraries = 
 contentLibraryService.readContentLibrary();
 return ResponseBuilder.buildSuccessResponse(contentLibraries);
 }
 }

服务

 @Service
 public class ContentLibraryService {
 @Autowired
 ContentLibraryMapper contentLibraryMapper;

 ContentLibrary content = new ContentLibrary();

 public List<ContentLibrary> readContentLibrary() {
  return contentLibraryMapper.readAllLibraryContent();
 }
 }

映射器

  @Repository
  @Mapper
  public interface ContentLibraryMapper {
   @Select("SELECT 
   * FROM 
   t_content_library")
   List<ContentLibrary> readAllLibraryContent();
   }

【问题讨论】：

标签： spring rest gradle mybatis pojo

【解决方案1】：

我得到的解决方案不是实现一长列列的确切解决方案。只不过是通过添加一个结果集来映射结果。


@Results({
        @Result(property ="id",column = "id"),
        @Result(property ="contentName",column = "content_name"),
        @Result(property ="contentPath",column = "content_path"),
        @Result(property ="createdTime",column = "created_time"),
})
    public List<ContentLibrary> readAllLibraryContent();

【讨论】：

【解决方案2】：

你需要开启MyBatis函数，将下划线映射到驼峰式。

如果您使用的是 Spring Boot，请将以下内容添加到 application.properties：

mybatis.configuration.map-underscore-to-camel-case=true

【讨论】：

是的，我已经添加了映射器配置，并且曾经使用它一段时间，对于表 t_user 没有任何问题。但现在它与其他表的响应空值发生冲突。