Express with Async Mongodb

express-async.js

const MongoClient = require('mongodb').MongoClient
const express = require('express')
const multer = require('multer')
const bodyParser = require('body-parser')

const upload = multer({ dest: 'uploads/' })
const router = express.Router()
const app = express()

app.use(bodyParser.json())
app.use(bodyParser.urlencoded({ extended: true }))

let db, m


const Post = {
  collection: 'posts',
  async query(params = []) {

    for (let k in this.relations) {
      let v = this.relations[k]
      let unwind = null
      if (v.unwind) {
        unwind = v.unwind
        delete v.unwind
      }
      params.push({ $lookup: v })
      if (unwind) {
        params.push({ $unwind: unwind })
      }
    }
    console.log(params);
    return await db.collection(this.collection).aggregate(params).toArray()
  },
  relations: {
    user: { from: 'users', localField: 'user_id', foreignField: 'id', as: 'user', unwind: '$user' },
    properties: { from: 'properties', localField: 'property_ids', foreignField: 'id', as: 'properties' },
  }
}

  const main = async () => {
    db = await MongoClient.connect('mongodb://localhost/yizhi')
    m = name => db.collection(name)
    // db.news = db.collection('news')
    // db.users = db.collection('users')
    // let ret = await db.collection('posts').aggregate([
    //   { $lookup: { from: 'users', localField: 'user_id', foreignField: 'id', as: 'user' } },
    //   { $unwind: '$user' },
    //   { $unwind: '$property_ids' },
    //   { $lookup: { from: 'properties', localField: 'property_ids', foreignField: 'id', as: 'properties' } },

    //   // {$unwind: '$properties'},
    //   { $limit: 1 }
    // ]).toArray()



    // let ret = await Post.query()

    // console.log(ret);
    // db.news.update({}, {$rename: {categoyIds: 'categoryIds'}})
    // db.collection('news').updateMany({id: {$lt: 5}}, {$set: {categoyIds: [1,2,3]}})
    // db.collection('news').updateMany({id: {$gte: 5}}, {$set: {categoyIds: [3,4,5]}})
  }
  main()
app.use((req, res, next) => {
  req.input = (name, defaultValue) => {
    let value = req.body[name] ? req.body[name] : (req.query[name] ? req.query[name] : defaultValue)
    return typeof defaultValue === 'number' ? Number(value) : (typeof defaultValue === 'boolean' ? Boolean(value) : value)
  }
  next()
})

router.get('/news', async (req, res, next) => {
  try {
    let filter = { categoryIds: 3 }
    // console.log(req.input('category', '').split(',').map(v => parseInt(v)));
    let total = await db.collection('news').find({
      categoryIds: { $gt: 1 }
    }).toArray()
    return res.json(total)
    let data = await db.collection('news').aggregate([
      { $match: filter },
      { $skip: req.input('skip', 0) },
      { $limit: req.input('limit', 10) },
      { $sort: { id: -1 } }
    ]).toArray()
    console.log(data);

    // res.append('total', total)
    res.send(data)
  } catch (e) {
    res.json(e)
  }
})

app.use('/api', router)
app.get('/posts', async (req, res) => {
  // let ret = await db.collection()
  let ret = await Post.query([
    {$limit: 10}
  ])
  res.send(ret)
})
app.listen(3000)