后端都不要了？我用 Serverless 3天做了个“现代应用”小项目

用户点击预约 → 微信小程序 → 云函数（预约接口）→ 数据库存储  
定时清理任务 → Timer → 云函数（清理接口）→ 数据库更新  

// functions/bookRoom/index.js

const cloud = require('wx-server-sdk')
cloud.init()

exports.main = async (event, context) => {
  const db = cloud.database()
  const { roomId, date, timeSlot, userId } = event

  const exists = await db.collection('booking')
    .where({ roomId, date, timeSlot })
    .get()

  if (exists.data.length > 0) {
    return { code: 409, msg: '该时间段已被预约' }
  }

  await db.collection('booking').add({
    data: {
      roomId,
      date,
      timeSlot,
      userId,
      createdAt: new Date()
    }
  })

  return { code: 200, msg: '预约成功' }
}

sls deploy --stage dev --region ap-guangzhou

// functions/clearExpired/index.js

exports.main = async (event, context) => {
  const db = cloud.database()
  const today = new Date().toISOString().split('T')[0]

  const result = await db.collection('booking')
    .where({ date: today, status: 'pending' })
    .remove()

  return { code: 200, msg: `清理完成，共删除 ${result.stats.removed} 条记录` }
}

functions:
  clearExpired:
    handler: index.main
    events:
      - timer: 'cron(0 22 * * *)' # 每天 22:00 执行

wx.cloud.callFunction({
  name: 'bookRoom',
  data: {
    roomId: 'A101',
    date: '2025-05-01',
    timeSlot: '14:00-15:00',
    userId: 'echo_wish'
  },
  success: res => {
    wx.showToast({ title: res.result.msg })
  },
  fail: err => {
    console.error('预约失败', err)
  }
})