本机MongoDB驱动程序Node.js-我们应该存储集合吗？

Question

I haven't been able to find any documents outlining if it's a bad / good idea to keep a reference to a collection so that it can be re-used after the db connection has been established.

for instance, in our database.ts which is called during our server start-up. It will grab the collections and store it for use in the module which can then be references throughout the project.

example of storing the collection

 /*database.ts*/ //module to keep 1 connection alive and allow us to have 1 instance of our collections. import {MongoClient, Db, Collection } from 'mongodb'; let uri: string = 'connection_string'; export let db: Db; export let usrCollection: Collection; export let bookCollection: Collection; export function initDb(cb: any) { MongoClient.connect(uri, function(err, database) { //handle err db = database; cb(); //returns now since db is assigned. }); } export function initCollections() { usrCollection = db.collection('users'); //non-async bookCollection = db.collection('book'); //non-async } /*app.ts*/ //in our express app when it start up import {db, initCollections, initDb} from './database'; initDb(function() { //this will hold up our server from starting BUT //there is no reason to make it async. initCollections(); }); 

what are some of the short coming of this pattern/build? what can I improve and what should I avoid for performance hits specificially with managing the collections.would this pattern keep my source code bug free or easy to find the bugs and extensible for the future? or is there even a better pattern - please no ext library aside from the native mongodb driver for node.js solutions, such as mongoose.

Answer 1

IMO, this is not a good practise. Users of database.ts will have to make sure that they have initialized these collections before using them. I will not even export any internal collections, since user should never care how the database is structured. You should export some operation functions like function addUser(user: User) {/.../} . There is a neat code sample created by MS .

//Edit. Yes, you can store collections reference internally so that you don't need to type collection names every time. It's easy to introduce bugs by ignoring singular and plural. The best practise would be:

import mongodb = require('mongodb');

const server = new mongodb.Server('localhost', 27017, {auto_reconnect: true})
const db = new mongodb.Db('mydb', server, { w: 1 });
db.open(function() {});
const userCollection =db.collection("users");
const bookCollection = db.collection("book");