Java Mybatis plus 语法中 避免sql循环

1. 查出全部数据并进行数据筛选过滤

在一对多的情况时，我们想把多的对象集合set进一的里面，需要避免循环sql

    @Override
    public R<List<ExRecord>> getExRecordAll(ExRecord exRecord) {

        // 获取用户id
        Integer userId = Math.toIntExact(SecurityUtils.getUserId());



        List<ExRecord> exRecords = exRecordMapper.selectList(new LambdaQueryWrapper<ExRecord>()
                // 根据用户id
                .eq(Objects.nonNull(userId), ExRecord::getUserId, userId)
                // 根据 试卷类型
                .eq(Objects.nonNull(exRecord.getPaperType()), ExRecord::getPaperType, exRecord.getPaperType())
        );

          // 过滤出全部id
        List<Integer> recordIds = exRecords.stream().map(ExRecord::getId).collect(Collectors.toList());

        // 过滤答题卡表中的id,并stream流进行分组
        Map<Integer, List<ExSheetAnswer>> collect = examSheetAnswerMapper.selectList(Wrappers.<ExSheetAnswer>lambdaQuery()
                .in(ExSheetAnswer::getRecordId, recordIds)).stream().collect(Collectors.groupingBy(ExSheetAnswer::getRecordId));

        // 根据map id 去赋值
        exRecords.forEach(record -> {
            record.setSheetAnswers(collect.getOrDefault(record.getId(), Collections.emptyList()));
        });


        return R.success(exRecords);
    }