node.js - MongoDB 不插入数据

Question

我是 Node.js 和 MongoDB 的新手，开始实现一些 POST API。我正在使用 MongoDB 通过 POST 插入数据，在终端上测试时显示数据库已创建，但在执行 POST 时显示找不到数据库的错误。我不确定我做错了什么。下面是我的代码

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

const app         = express();
const port        = 8080;
var url = "mongodb://localhost:27017/mydb"

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

app.listen(port, () => {
  console.log('We are live on ' + port);
});

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  console.log("Database created!");
  db.close();
});

app.post('/api/notes', function(req, res) {

    var myobj = { text: req.body.body, title: req.body.title };
    var dbase = db.db("mydb");
    dbase.collection('notes').insertOne(myobj, function(err, result) {
      if (err) {
        res.send({ 'error': 'An error has occurred' });
      } else {
        res.send(result.ops[0]);
      }
    });
});

Answer 1

您的db在外部不可用，这就是您收到错误的原因。

试试这个方法:

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  console.log("Database created!");
 global.db=db;
//don't close connection here if you want to use outside just put it as global
});

您可以引用https://groups.google.com/forum/#!msg/node-mongodb-native/mSGnnuG8C1o/Hiaqvdu1bWoJ为了更好地理解 MongoDB 原生连接

其中说:

You open do MongoClient.connect once when your app boots up and reuse the db object. It's not a singleton connection pool each .connect creates a new connection pool.