关于useGeneratedKeys获取自增主键

场景描述：

一级菜单和二级菜单通过外键关联，在添加一级菜单同时添加二级菜单时，将一级菜单的主键id值作为二级菜单外键id值

问题解决：

可通过mybatis在insert后通过useGeneratedKeys获取一级菜单自增主键，在添加二级菜单时作为外键id值继续存入二级菜单

Java Bean

/**  * 一级列表名称  * @author  xj  */ @Entity @Getter @Setter @Table(name = "tb_top_type") public class TopType extends BaseEntity implements Serializable {      /**      * 类型主键id      */     @Id     @GeneratedValue(strategy = GenerationType.IDENTITY)     @Column(name="id",unique = true)     private Long id;      /**      * 一级列表名称      */     @Column(name = "top_type_name", unique = true)     private String topTypeName;      /**      * 一级列表创建时间      */     @Column(name = "top_type_ctime", unique = true)     private String topTypeCtime;      /**      * 关联二级菜单      */     private List<ProductType> types; }

@Entity @Getter @Setter @Table(name = "tb_type") public class ProductType extends BaseEntity implements Serializable {      /**      * 类型主键id      */     @Id     @GeneratedValue(strategy = GenerationType.IDENTITY)     @Column(name="id",unique = true)     private Long id;       /**      * 类型名称      */     @Column(name = "type_name", unique = true)     private String typeName;      /**      * 类型创建时间      */     @Column(name = "type_ctime", unique = true)     private String typeCtime;      /**      * 类型修改时间      */     @Column(name = "type_uptime", unique = true)     private String typeUptime;      /**      * 外键id      */     @Column(name = "top_type_id", unique = true)     private Long topTypeId;      /**      * 商品集合      */     private List<Product> products;  }

@Slf4j @RestController @RequestMapping("/api/topType") @Api(tags = "一级菜单列表服务") public class TopTypeController extends BaseController{     @Autowired     private ITopTypeService service;          /**      * 保存菜单列表信息      * @param topType      * @return AjaxReslut      */     @ApiOperation(value = "保存菜单列表信息",notes = "传入菜单列表信息")     @RequestMapping(value ="/add",method = RequestMethod.POST)     public AjaxResult add(@RequestBody TopType topType){         topType.setTopTypeCtime(DateUtils.nowTime());         return service.add(topType);     }    }

Service层:

@Service @Slf4j @Transactional public class TopTypeServiceImpl implements ITopTypeService {     @Autowired     private ITopTypeMapper mapper;      @Autowired     private IProductTypeMapper typeMapper;         @Override     public AjaxResult add(Object o) {         try {             /** 一级菜单*/             TopType topType = (TopType) o;             int rows = mapper.add(topType);             if (rows<0){                 return AjaxResult.error("添加一级菜单失败！");             }             /** 二级菜单*/             List<ProductType> types = topType.getTypes();             types.stream().forEach(                     productType->productType.setTopTypeId(topType.getId())             );             if (null != types) {                 typeMapper.addList(types);             }             return AjaxResult.success("添加成功");         } catch (Exception e) {             TransactionAspectSupport.currentTransactionStatus().setRollbackOnly();             log.error("添加菜单信息失败:" + e.getMessage());             return AjaxResult.error("添加失败:" + e.getMessage());         }     }    }

mapper层

<!-- 保存菜单信息 --> <insert id="add" parameterType="TopType" useGeneratedKeys="true" keyProperty="id" >         INSERT INTO tb_top_type(         top_type_name, top_type_ctime         )         VALUES(         #{topTypeName},         #{topTypeCtime}      ) </insert>

一定要注意useGeneratedKeys keyProperty 保证主键id是自动增长的