Mybatis-plus里面的getOne用法

QueryWrapper qw = new QueryWrapper();
        qw.eq("resident_id",residentId);
        SysResidentReplenish sysResidentReplenish = sysResidentReplenishService.getOne(qw);
        if (sysResidentReplenish != null){
            return AjaxResult.error("该居民已建档");
        }

嗷嗷........