深入解析：微服务项目-＞在线oj系统(Java-Spring)--增删改

后端代码

增添

toR

QuestionAddDTO

了解前端添加一个问题需要我们传入什么数据

package com.bite.system.model.question.DTO;
import lombok.Getter;
import lombok.Setter;
@Getter
@Setter
public class QuestionAddDTO {
    private String title;
    private Integer difficulty;
    private Long timeLimit;
    private Long spaceLimit;
    private String content;
    private String questionCase;
    private String defaultCode;
    private String mainFuc;
}

Controller

  @PostMapping("/add")
    public R add(@RequestBody QuestionAddDTO questionAddDTO){
        return toR(questionService.add(questionAddDTO)) ;
    }

Service

首先通过mapper进行查询，查询我们的数据库里面是否存在相同标题的题目，如果有，抛出异常，然后异常统一捕获，返回给前端报错

如果所增加题目并不在数据库里面，则新创建一个Question对象，然后将我们前端传来参数（DTO）复制给question对象，然后让数据库进行插入操作

    @Override
    public int add(QuestionAddDTO questionAddDTO) {
        List list=questionMapper.selectList(new LambdaQueryWrapper().eq(Question::getTitle,questionAddDTO.getTitle()));
        if(CollectionUtil.isNotEmpty(list)){
            throw new ServiceException(ResultCode.FAILED_ALREADY_EXISTS);
        }
        Question question = new Question();
        BeanUtil.copyProperties(questionAddDTO, question);
        int insert = questionMapper.insert(question);
        return insert;
    }

如果插入成功，新增数据将会出现在我们列表的第一个，否则传给前端错误原因

修改

@Data
public class QuestionEditDTO extends QuestionAddDTO{
    private Long questionId;
}

当我们点开修改页面的时候，会根据id自动获取到相关的详细内容

  @GetMapping("/detail")
    public R detail(Long questionId) {
        return R.ok(questionService.detail(questionId));
    }

首先通过id进行查询，看是否存在这本书，如果不存在抛出异常

如果数据库中有该题，则从数据库里面查询到数据，然后创建一个返回给前端的VO

@Data
public class QuestionDetailVO {
    private Long questionId;
    private String title;
    private Integer difficulty;
    private Long timeLimit;
    private Long spaceLimit;
    private String content;
    private String questionCase;
    private String defaultCode;
    private String mainFuc;
}

然后将值复制给这个VO类，返回VO

 @Override
    public QuestionDetailVO detail(Long questionId) {
        Question question = questionMapper.selectById(questionId);
        if (question == null) {
            throw new ServiceException(ResultCode.FAILED_NOT_EXISTS);
        }
        QuestionDetailVO questionDetailVO = new QuestionDetailVO();
        BeanUtil.copyProperties(question, questionDetailVO);
        return questionDetailVO;
    }

然后继续进行修改操作

  //  /question/edit
    @PutMapping("/edit")
    public R edit(@RequestBody QuestionEditDTO questionEditDTO) {
        return toR(questionService.edit(questionEditDTO));
    }

通过前端的输入框获得数据，然后点击按键去进行调用后端函数，将参数传入赋值

  @Override
    public int edit(QuestionEditDTO questionEditDTO) {
        Question oldQuestion = questionMapper.selectById(questionEditDTO.getQuestionId());
        if (oldQuestion == null) {
            throw new ServiceException(ResultCode.FAILED_NOT_EXISTS);
        }
        oldQuestion.setTitle(questionEditDTO.getTitle());
        oldQuestion.setDifficulty(questionEditDTO.getDifficulty());
        oldQuestion.setTimeLimit(questionEditDTO.getTimeLimit());
        oldQuestion.setSpaceLimit(questionEditDTO.getSpaceLimit());
        oldQuestion.setContent(questionEditDTO.getContent());
        oldQuestion.setQuestionCase(questionEditDTO.getQuestionCase());
        oldQuestion.setDefaultCode(questionEditDTO.getDefaultCode());
        oldQuestion.setMainFuc(questionEditDTO.getMainFuc());
        return questionMapper.updateById(oldQuestion);
    }

通过id去搜索搜索之前存入的数据，如果不存在抛出异常，

然后对之前的内容进行赋值，之后使用Mapper进行修改

删除

有了前面俩个的学习，我们接下来就会轻松许多，我们这里后端只做第三步

直接通过id去数据库进行删除操作

    //  /question/delete
    @DeleteMapping("/delete")
    public R delete(Long questionId) {
        return toR(questionService.delete(questionId));
    }

 @Override
    public int delete(Long questionId) {
        Question question = questionMapper.selectById(questionId);
        if (question == null) {
            throw new ServiceException(ResultCode.FAILED_NOT_EXISTS);
        }
        return questionMapper.deleteById(questionId);
    }