How MyBatis 3.5’s Optional Support Eliminates Boilerplate Null Checks

Before

Typical MyBatis code returns an entity and requires explicit null‑check.

@Mapper
public interface UserMapper {
    @Select("select * from user where id = #{id}")
    User selectById(Long id);
}

Controller example with null check.

public class UserController {
    @Autowired
    private UserMapper userMapper;

    @GetMapping("/{id}")
    public User findById(@PathVariable Long id) {
        User user = this.userMapper.selectById(id);
        if (user == null) {
            // throw exception or handle
        }
    }
}

After

MyBatis 3.5 allows mapper methods to return Optional<User>, eliminating manual null‑checking code.

@Mapper
public interface UserMapper {
    @Select("select * from user where id = #{id}")
    Optional<User> selectById(Long id);
}

Controller can now directly return the entity or throw an exception.

public class UserController {
    @Autowired
    private UserMapper userMapper;

    @GetMapping("/{id}")
    public User findById(@PathVariable Long id) {
        return this.userMapper.selectById(id)
                .orElseThrow(() -> new IllegalArgumentException("This user does not exist!"));
    }
}

The new Optional feature greatly reduces boiler‑plate null‑checking code.

Limitations

MyBatis Generator and popular third‑party mappers (e.g., MyBatis‑General‑Mapper) have not yet been updated to return Optional. Issues have been opened and may be resolved with a small PR.

Dependency

<dependency>
  <groupId>org.mybatis.spring.boot</groupId>
  <artifactId>mybatis-spring-boot-starter</artifactId>
  <version>2.0.0</version>
</dependency>

References

MyBatis General Mapper: https://github.com/abel533/Mapper

Generator wiki: https://github.com/abel533/Mapper/wiki/4.1.mappergenerator

Issue requesting Optional support: https://github.com/abel533/Mapper/issues/558

Demo project on GitHub: https://github.com/eacdy/spring-boot-study/tree/master/spring-boot-mybatis-optional

Demo on Gitee: https://gitee.com/itmuch/spring-boot-study/tree/master/spring-boot-mybatis-optional