6.1040 Social Media Starter Backend Code

Getting Started

If you are using VSCode/VSCodium, install the ESLint and Prettier extensions. The project is already configured to use ESLint and Prettier, but feel free to add your own rules if you want. Right now, the code is formatted on save; you can change this in .vscode/settings.json by disabling editor.formatOnSave.

Run npm install to install dependencies.

Creating MongoDb Atlas Instance

To run the server, you need to create a MongoDb Atlas instance and connect your project. Feel free to follow the instructions below or use these slides.

Create your MongoDB Atlas account.
When selecting a template, choose the free option, M0.
At the Security Quickstart page, select how you want to authenticate your connection and keep the rest of the defaults. Make sure to allow access to all IPs as shown in this slide.
Once created, click the CONNECT button, select driver, and copy the srv connection string. If using username and password, the url should look something like this: mongodb+srv://<username>:<password>@cluster0.p82ijqd.mongodb.net/?retryWrites=true&w=majority. Make sure to replace username and password with your actual values.
Now go to your project files and create a new file at the root directory called .env (don't forget the 'dot' at the front). Add the line (without < and >)
```
MONGO_SRV=<connection url>
```
to the .env file.

Congrats! You're ready to run locally! Don't hesitate to reach out if you run into issues.

Running Locally

Run npm start to start the server and the testing client. If you make changes to code, you need to manually restart the server.

Run npm watch to watch for changes and restart the server automatically. Note that this is not recommended when actively developing; use this when testing your code so your small changes get reflected in the server.

Testing

There is a testing client under public directory. Locate to http://localhost:3000 (or a different port if you changed it) to see the testing client. Add more operations to public/util.ts to test your server code. Make sure to refresh the page after making changes to the client code. Add some fancy CSS to make your page look nicer!

Keep in mind that we are using MongoStore for session management, so your session will be persisted across server restarts.

Deploying to Vercel

Fork this repo.
Create a new project on Vercel and link it to your GitHub project.
Under "Build & Development Settings", change "Output Directory" to dist/public.
Add the following environment variables to your Vercel project: Key: MONGO_SRV, Value: <your mongo connection string from .env file>
Deploy!

Understanding the Structure

The main entry point to the server is api/index.ts. This is how the server is started and how the routes are registered. We would usually put this file under server/, but Vercel requires the entry point to be under api/ directory.

The code for the server is under server/ directory, which includes both concept and RESTful API implementations.

Here's an overview of the files and directories:

server/concepts contains the concept implementations. Note that we try to keep concepts as modular and generic as possible.
server/concepts/errors.ts contains the base error classes you can either directly use or extend from. You are free to add more base errors in that file if you need to (e.g., if your route needs to return I am a teapot error).
framework/ contains the framework code that does the magic to convert your route implementations and error handling into Express handlers. You should't edit this directory, but feel free to take a look!
server/app.ts contains your app definition (i.e., concept instantiations).
server/db.ts contains the MongoDb setup code. You don't need to edit this file.
server/routes.ts contains the code for your API routes. Try to keep your route definitions as simple as possible.
server/responses.ts contains the code for formatting your responses and errors into a more user-friendly format for the front-end. For example, it would be better if your front-end receives barish is not the author of this post instead of 64e52a1f5ffc7d0d48a0569d is not the author of this post.