Mybatis中useGeneratedKeys、keyProperty、keyColumn的使用

阳光穿透心脏的1/2处 2023-09-30 08:11 11阅读 0赞

useGeneratedKeys
    在mybatis的XML映射器中设置useGeneratedKeys=true，是为了在执行insert 、update操作后能获取操作成功后的插入对象的自增主键id
    
    keyProperty
    keyProperty指定在Java 实体类中对应的主键
    
    keyColumn
    keyColumn指的是数据库表中自增主键的字段名

插入数据时，实体类中未提供id值  
通过在xml中设置参数，mybatis会设置传过去的实体类goodsReview中Id的值，先插入数据后把数据库中自动生成的Id值映射到实体类goodsReview中Id里，方便service层中后续操作。前提该数据是主键且可以在数据库中自动生成

keyColumn="id" keyProperty="id" useGeneratedKeys="true"

实体类

@Data
    @AllArgsConstructor
    @NoArgsConstructor
    public class GoodsReview {
        
        /**
        * 主键
        */
        private Integer id;
    
        /**
        * 商品ID
        */
        private String goodId;
    
        /**
        * 用户ID
        */
        private String userId;
    
        /**
        * 评论内容
        */
        private String reviewContent;
    }

service层

@Service
    public class GoodsReviewService {
        
    
        @Resource
        private GoodsReviewMapper goodsReviewMapper;
    
        public GoodsReview addReview(GoodsReview goodsReview) {
        
            return goodsReviewMapper.addReview(goodsReview);
        }
    
    }

Mapper层

@Mapper
    public interface GoodsReviewMapper {
        
    
        /**
         * 插入数据
         *
         * @param goodsReview 实体类型数据
         * @return  影响行数
         */
        GoodsReview addReview(GoodsReview goodsReview);
    }

xml

<insert id="addReview" keyColumn="id" keyProperty="id" parameterType="com.onlinestore.pojo.GoodsReview"
                useGeneratedKeys="true">
            
            insert into goods_review (good_id, user_id, review_content
            )
            values (#{goodId,jdbcType=VARCHAR}, #{userId,jdbcType=VARCHAR}, #{reviewContent,jdbcType=LONGVARCHAR}
            )
    </insert>

数据前后变化：

{
        
    	"Id":"",
    	"goodId":"111",
    	"userId":"123tt",
    	"reviewContent":"tttttttttttttttt"
    }
    变为
    {
        
    	"Id":"123",
    	"goodId":"111",
    	"userId":"123tt",
    	"reviewContent":"tttttttttttttttt"
    }

参考文章：  
[文章1 ： https://blog.csdn.net/Du939/article/details/100014905][1 _ https_blog.csdn.net_Du939_article_details_100014905].  
[文章2 ： https://blog.csdn.net/sinat\_30474567/article/details/51395247][2 _ https_blog.csdn.net_sinat_30474567_article_details_51395247].

[1 _ https_blog.csdn.net_Du939_article_details_100014905]: https://blog.csdn.net/Du939/article/details/100014905
[2 _ https_blog.csdn.net_sinat_30474567_article_details_51395247]: https://blog.csdn.net/sinat_30474567/article/details/51395247