Need ideas about some SW/application for writing

Han Mai — Sat, 19 Jun 2021 16:49:57 +0000

Hi, I want to write about some technical discussion about system designs, architecture designs, programming techniques and how to deal with troubles in real-world but I've found that it is very difficult to just explain topics via multiple arbitrary and unconnected examples. I've got some topics in my mind but I cannot convey them into words. My writing is not good enough. So I'm thinking of implementing some real product while writing about it at a same time. I can post all the design considerations here and will receive feedbacks which will help me (and maybe other people) a lot.

The problem is that I cannot think of any ideas about software/applications that are not only practical but also useful for real-life use cases. Simple case studies are good but I'm afraid of that the readers will lose the interest. So any suggestion would be welcome and appreciate.

Thank you very much.

Stop using the mongoose's default connection

Han Mai — Mon, 09 Sep 2019 02:29:55 +0000

Look at the below typical example of mongoose use.

const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost:27017/myapp', {useNewUrlParser: true});
var MyModel = mongoose.model('Test', new Schema({ name: String }));
// Works
MyModel.findOne(function(error, result) { /* ... */ });

What if we want to make another connections? Or if we want to connect to another database? We can't use mongoose.connect() again, mongoose won't know which one we want to interact with. And don't ever think of creating different modules where separated mongoose objects are created and used because require() doesn't work that way, mongoose object is cached for the first time it is imported.

The connection object is used to create and retrieve models. Models are always scoped to a single connection. Please be aware that mongoose creates a default connection when we call mongoose.connect(). We can access the default connection using mongoose.connection.

Not everybody notices that. So my suggestion is that we avoid using mongoose.connect(). Instead of that, we use mongoose.createConnection(). By this way, we can save much time for other developers who will maintain and extend the project in the future. We implicitly ask them to aware the fact of mongoose's default connection.

The above example may be re-written as the following.

const mongoose = require('mongoose');
var connection = mongoose.createConnection('mongodb://localhost:27017/myapp',
                                           {useNewUrlParser: true});
var MyModel = connection.model('Test', new Schema({ name: String }));
// Works
MyModel.findOne(function(error, result) { /* ... */ });

Reference API: https://mongoosejs.com/docs/connections.html
** This post is copy from my personal blog https://rainforest01.blogspot.com/2019/08/stop-using-mongooses-default-connection.html

Forem: Han Mai

Need ideas about some SW/application for writing

Stop using the mongoose's default connection