无法读取未定义的MongoDB的属性“Collection”

Question

const express = require('express')
const bodyParser= require('body-parser')
const MongoClient = require('mongodb').MongoClient
const app = express()
app.use(bodyParser.urlencoded({extended: true}))

const url = 'mongodb://localhost:27017/testdb';

var db
MongoClient.connect(url, function(err, client) {
  if (err) return console.log(err)
  var db = client.db('testdb');

})

app.post('/quotes', (req, res) => {
    var collectionName = 'quotes';
    var collection = db.collection(collectionName);
    collection.save(req.body, (err, result) => {
    if (err) return console.log(err)

    console.log('saved to database')
    res.redirect('/')
  })
})

TypeError：无法读取app.post(/var/www/html/express/simplecrud/server.js:20:21)层未定义的属性“collection”。处理[as handle_request](/var/www/html/express/simplecrud/node_modules/express/lib/router/layer.js:95:5)层的下一个(/var/www/html/express/simplecrud/node_modules/express/lib/router/layer.js:137:13)层的下一个(/var/www/html/express/simplecrud/node_modules/express/lib/router/layer.js:95:5)在/var/www/html/express/simplecrud/node_modules/express/lib/router/index.js:281:22在function.process_params(/var/www/html/express/simplecrud/node_modules/express/lib/router/index.js:335:12)在下一个/lib/read.js:130:5at invokeCallback(/var/www/html/express/simplecrud/node_modules/raw-body/index.js:224:16)

Im使用Mongodb 3.1

Answer 1

嘿，

尝试:常量url='mongoDb://localhost:27017'；

更新：根据MongoDB包v3.x，DB的声明是单独进行的，而不是作为URL的一部分。更多信息请参见：https://www.npmjs.com/package/mongoDb