In MyBatis-Plus, org.apache.ibatis.binding.BindingException occurs.

I have searched through various GPT and CSDN articles, but I haven't found the correct solution. It is commonly mentioned that the issue is related to the XML file location...

Error Code#

User Class

@Data
@NoArgsConstructor
@AllArgsConstructor
@TableName("user")
public class User {
    @TableField("user_id")
    private Long userId;       // User ID
    @TableField("user_name")
    private String userName;   // Username
    @TableField("user_password")
    private String userPassword; // User password
    @TableField("user_authority")
    private Integer userAuthority; // User authority
}

Mapper Interface

@Mapper
public interface UserMapper extends BaseMapper<User> {

}

Test Method

@SpringBootTest
public class UserTest {
    @Autowired
    private UserMapper userMapper;

    // Select user by id
    @Test
    public void testSelectById() {
        User user = userMapper.selectById(1);
        System.out.println(user);
    }
}

Solution and Reason#

Since the primary key is not specified in the User entity class, the selectById method cannot find the primary key.

Therefore, the solution is to add @TableId(value = "user_id", type = IdType.AUTO) in the User entity class.

@Data
@NoArgsConstructor
@AllArgsConstructor
@TableName("user")
public class User {
    // Add it here
    @TableId(value = "user_id", type = IdType.AUTO)
    @TableField("user_id")
    private Long userId;       // User ID
  
    @TableField("user_name")
    private String userName;   // Username
    @TableField("user_password")
    private String userPassword; // User password
    @TableField("user_authority")
    private Integer userAuthority; // User authority
}