为什么我不能在我的应用程序中看到我的Mongodb集合?

安装“mongodb”npm模块。它是NodeJs的官方MongoDB客户端。

// Create a Mongo Client Instace to connect to the MongoDB Database
// and perform various functions.
const MongoClient = require( 'mongodb' ).MongoClient;
// Store the URL of your MongoDB Server
const mongoURL = "mongodb://localhost:27017/";
// Stored the name of the Database you wanna connect to.
const dbName = "testdb";

// Create a new Mongo DB client that will connect to the MongoDB Server.
const client = new MongoClient(mongoURL);

// Connect the Client to the MongoDB Server.
client.connect( (err) => {

    // Error handling of some sort.
    if(err) throw err;

    console.log( 'connected!' );

    // Connect to the database you want to manage using the dbName you
    // stored earlier.
    const db = client.db( dbName );

    // Store the name of the collection you want to read from.
    // this can be created above near the dbName.
    const collectionName = "testCol"

    // Connect to the collection that you stored above.
    const collection = db.collection( collectionName );

    // Query the MongoDB database and log the results, if any.
    collection.find({}).toArray( (err, docs) => {
        console.log(docs);
    } );

} )

const client = new MongoClient( mongoURL, { useNewUrlParser: true } );

而不是

const client = new MongoClient(mongoURL);

http://mongodb.github.io/node-mongodb-native/3.1/quick-start/quick-start/