nestjs-cqrs: A TypeScript repository from kenchoong

Introduction

This repo is to demonstrate the usage and implementation of following

Nestjs CQRS
Nextjs
Postgres
TypeORM
Stripe
Stripe webhook
Docker

Setup

First clone this repo:

$ git clone https://github.com/kenchoong/nestjs-cqrs.git

Setup Stripe for our app

Download Stripe CLI here
extract the zip in a local folder example D:/Desktop/Stripe

Setup Stripe CLI

$ cd D:/Desktop/Stripe

// login to dashboard
$ stripe login

// forward the request to our localhost endpoint
$ stripe listen --forward-to localhost:3002/payment/stripe-webhook

Here you will get a secret(string) in CLI, then paste it in '/backend/.env'
```
STRIPE_WEBHOOK_SECRET="PASTE_SECRET_FROM_CLI"
```

End up ur /backend/.env will look like this

STRIPE_SK_TEST="THE_KEY_FROM_STRIPE_DASHBOARD" <- Get from Stripe Dashboard
STRIPE_WEBHOOK_SECRET="SECRET_FROM_STRIPE_CLI" <-- get from STRIPE CLI

Note: This need to setup the credential probably, if not you will facing this issue when Stripe hit the webhook

Test the CLI
```
$ stripe trigger payment_intent.succeeded
```
For info: read here

If everything setup probably, you will get the outcome like this in Stripe CLI
Paste Stripe Publishable key to frontend/.env file here, to look like this
```
NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY="PASTE_YOUR_KEY_HERE"
```

Test in localhost

Pull Postgres and PgAdmin

$ docker-compose -f docker-compose.dev.yml up

Localhost backend
```
$ cd backend

$ yarn

$ yarn start:dev
```
Now go to http://localhost:3002/api see the Swagger API documentation
Localhost Frontend
```
$ cd frontend

$ yarn

$ yarn dev
```
Go to http://localhost:3000 for frontend

Database Migration and ERD diagram

Database look like this, just to meet the requirements:

The migration script already setup in package.json, so u can run this:

$ cd backend

$ yarn migrate:create [THE_MIGRATION_NAME]

$ yarn migrate:generate [THE_MIGRATION_NAME]

$ yarn migrate:run

// migration file will be in /backend/src/common/db/migrations

Note: if in localhost, generate migration having the connect database problem,

first, need to start the postgres server, if it still exist,
hardcode the host and port in this file, like this:
```
host: localhost 
port: 6543
```

This only as a temporary solution, and remember change back to process.env like in original when build docker image, else later docker-compose up, cant connect to postgres

Some Explaination for the Backend

Using Domain Driven Design to structure the backend, I will explain this in Layman Terms below

The app will consists of 5 Layers

Defined each functionality into separate module

Now I have orders, users, product, payment, each responsible for each functionality
Domain Layer

AKA The root of each module. For example, users module, then here will defined,
- what properties(data) a user will have,
- validation of the each properties value when insert to db, what a user can do will include AggreateRoot, Factory, ValueObject in this layer.
- will defined interface in repo.ts or query.ts file , to expose the interface for infrastructure and application layer to access the properties of AggreateRoot
Application Layer

Use case. Mostly mean how you want to do with the data, for example create-user, get-product-by-id, each use-case will in separate folder. Right now is CQRS pattern, so inside it will contain Command, Query, Handler class. Over here is only contain business logic aka organize the data using the domain before go in infrastructure layer.
Infrastruture Layer

The underlying infrastructure needed to support module, like Database, Cache, Messaging, another DB, all this will separate into each individual folder. Right now is just Postgres.

Interface layer

A surface to let real API user to hit on. Controller and Data Transfer Object for request and response.Basically the data flow like this, below.

// --> Data in:
interface -> application -> domain -> infrastructure(Entity)

// <-- Data out:
interface <- application <- domain <- infrastructure(Entity)

Event layer (only when needed)

Example, received event from Stripe in Payment module, then need to update the orderStatus in order module. To separate this, we use event. Payment module trigger an event, Order module receive it, will update the db.

You can see the flow start from here

Deployment

In root folder

$  docker-compose -f docker-compose.yml up --build

Let the image build, this will take estimate 500 seconds to initialize backend, frontend, postgres, and pgadmin

See the outcome

localhost:3000 Nextjs app

localhost:3002/api Swagger Documentation

localhost:5555 pgadmin

login using POSTGRES_USER and POSTGRES_PASSWORD defined in /backend/.env

connect to server using value of hostname = POSTGRES_HOSTNAME ,port = 5432 POSTGRES_USER and POSTGRES_PASSWORD as well

Good reads

Summary

In this project, mainly to showcase the Domain Driven Design for the backend. If problem, open the issue. Cant make a 1 command setup because need to build Stripe credential inside the docker.