TypeScript CRUD Rest API, using: Nest.js, TypeORM, Postgres, Docker and Docker Compose

Let's create a CRUD Rest API in Typescript using:

NestJS (NodeJS framework)

TypeORM (ORM: Object Relational Mapper)

Postgres (relational database)

Docker (for containerization)

Docker Compose

If you prefer a video version:

All the code is available in the GitHub repository (link in the video description): youtube.com/live/gqFauCpPSlw

Here is a schema of the architecture of the application we are going to create:

crud, read, update, delete, to a NestJS app and Postgres service, connected with Docker compose. Postman and Tableplus to test it

We will create 5 endpoints for basic CRUD operations:

Create

Read all

Read one

Update

Delete

Here are the steps we are going through:

Create a new NestJS application

Create a new module for the users, with a controller, a service and an entity

Dockerize the application

Create docker-compose.yml to run the application and the database

Test the application with Postman and Tableplus

We will go with a step-by-step guide, so you can follow along.

Requirements:

Node installed (I'm using v16)

Docker installed and running

(Optional): Postman and Tableplus to follow along, but any testing tool will work

NestJS CLI (command below)

💻 Create a new NestJS application

We will create our project using the NestJS CLI

if you don't have the NestJS CLI installed, you can install it with:

COPY

npm install -g @nestjs/cli

This will install the NestJS CLI globally, so you can use it from anywhere.

Then you can create move to your workspace folder and create a new NestJS application with (you can replace nest-crud-app with what you want):

COPY

nest new nest-crud-app

Just hit enter to go with the default options. This will create a new project for you (it will take a while).

successfully created project nest-crud-app

Step into the directory:

COPY

cd nest-crud-app

Now install the dependencies we need:

COPY

npm i pg typeorm @nestjs/typeorm @nestjs/config

pg: Postgres driver for NodeJS

typeorm: ORM for NodeJS

@nestjs/typeorm: NestJS module for TypeORM

@nestjs/config: NestJS module for configuration

Once it's done, open the project in your favorite editor (I'm using VSCode).

COPY

code .

Before we start coding, let's test if everything is working.

COPY

npm start

And we should see something like that:

Hello World on the left, vs code witn npm start command run, NestJS scaffold project

Now you can stop the server with Ctrl + C.

🐈‍⬛ Create the NestJS application

Now we are going to work on the NestJS application.

Let's create a new module, a controller, a service and an entity.

COPY

nest g module users

nest g controller users

nest g service users

touch src/users/user.entity.ts

This will create the following files (and 2 more test files we will not use)

src/users/users.module.ts

src/users/users.controller.ts

src/users/users.service.ts

src/users/user.entity.ts

Your folder structure should look like that:

folder structure of the NestJS app, the 4 files are ina folder called users in src

Now let's work on these 4 files.

User Entity

Open the file "src/users/user.entity.ts" and populate it like that:

COPY

import { Entity, PrimaryGeneratedColumn, Column, } from "typeorm";

@Entity()

export class User {

@PrimaryGeneratedColumn()

id: number;

@Column()

name: string;

@Column()

email: string;

}

Explanation:

We are using the decorator @Entity() to tell TypeORM that this is an entity

We are using the decorator @PrimaryGeneratedColumn() to tell TypeORM that this is the primary key of the table

We are using the decorator @Column() to tell TypeORM that this is a column of the table

We are creating a User entity with 3 columns: id, name and email.

User Service

Open the file "src/users/users.service.ts" and populate it like that:

COPY

import { Injectable } from '@nestjs/common';

import { InjectRepository } from '@nestjs/typeorm';

import { Repository } from 'typeorm';

import {User} from './user.entity';

@Injectable()

export class UserService {

constructor(

@InjectRepository(User)

private userRepository: Repository<User>,

) {}

async findAll(): Promise<User[]> {

return this.userRepository.find();

}

async findOne(id: number): Promise<User> {

return this.userRepository.findOne({ where: { id } });

}

async create(user: Partial<User>): Promise<User> {

const newuser = this.userRepository.create(user);

return this.userRepository.save(newuser);

}

async update(id: number, user: Partial<User>): Promise<User> {

await this.userRepository.update(id, user);

return this.userRepository.findOne({ where: { id } });

}

async delete(id: number): Promise<void> {

await this.userRepository.delete(id);

}

Explanation:

We are using the decorator @Injectable() to tell NestJS that this is a service

We are using the decorator @InjectRepository(User) to tell NestJS that we want to inject the repository of the User entity

We are using the decorator @Repository(User) to tell NestJS that we want to inject the repository of the User entity

We are creating a UserService with 5 methods: findAll, findOne, create, update and delete

User Controller

Open the file "src/users/users.controller.ts" and populate it like that:

COPY

import { Controller, Get, Post, Body, Put, Param, Delete, NotFoundException } from '@nestjs/common';

import { UsersService } from './users.service';

import { User } from './user.entity';

@Controller('users')

export class UsersController {

constructor(private readonly usersService: UsersService) {}

//get all users

@Get()

async findAll(): Promise<User[]> {

return this.usersService.findAll();

}

//get user by id

@Get(':id')

async findOne(@Param('id') id: number): Promise<User> {

const user = await this.usersService.findOne(id);

if (!user) {

throw new NotFoundException('User does not exist!');

} else {

return user;

}

//create user

@Post()

async create(@Body() user: User): Promise<User> {

return this.usersService.create(user);

}

//update user

@Put(':id')

async update (@Param('id') id: number, @Body() user: User): Promise<any> {

return this.usersService.update(id, user);

}

//delete user

@Delete(':id')

async delete(@Param('id') id: number): Promise<any> {

//handle error if user does not exist

const user = await this.usersService.findOne(id);

if (!user) {

throw new NotFoundException('User does not exist!');

}

return this.usersService.delete(id);

}

Explanation:

We are using the decorator @Controller('users') to tell NestJS that this is a controller, and that the route is "users"

We are defining the constructor of the class, and injecting the UserService

We are defining 5 methods: findAll, findOne, create, update and delete, decorated with the HTTP method we want to use, and we are using the UserService to call the corresponding method

User Module

Open the file "src/users/users.module.ts" and populate it like that:

COPY

import { Module } from '@nestjs/common';

import { UserController } from './users.controller';

import { UserService } from './users.service';

import { TypeOrmModule } from '@nestjs/typeorm';

import { User } from './user.entity';

@Module({

imports: [TypeOrmModule.forFeature([User])],

controllers: [UserController],

providers: [UserService]

})

export class UsersModule {}

Explanation:

We are importing the TypeOrmModule and the User entity (UserController and UserService are already imported)

We are using the decorator @Module() to tell NestJS that this is a module

We add the TypeOrmModule.forFeature([User]) to the imports array, to tell NestJS that we want to use the User entity

Update the Main Module

Open the file "src/app.module.ts" and populate it like that:

COPY

import { Module } from '@nestjs/common';

import { AppController } from './app.controller';

import { AppService } from './app.service';

import { UsersModule } from './users/users.module';

import { TypeOrmModule } from '@nestjs/typeorm';

import { ConfigModule } from '@nestjs/config';

@Module({

imports: [

ConfigModule.forRoot(),

UsersModule,

TypeOrmModule.forRoot({

type: process.env.DB_TYPE as any,

host: process.env.PG_HOST,

port: parseInt(process.env.PG_PORT),

username: process.env.PG_USER,

password: process.env.PG_PASSWORD,

database: process.env.PG_DB,

entities: [__dirname + '/**/*.entity{.ts,.js}'],

synchronize: true,

}),

controllers: [AppController],

providers: [AppService],

})

export class AppModule {}

Explanation:

We are importing the ConfigModule, the UsersModule and the TypeOrmModule

We are importing the ConfigModule, UsersModule and TypeOrmModule in the imports array

For TypeOrmModule, we are using the method forRoot() to tell NestJS that we want to use the default connection, and we define some environment variables to connect to the database. We will set the in the docker-compose.yml file soon.

the synchronize option is set to true, so that the database schema is automatically updated when the application is started

🐳 Dockerize the application

Let's create 3 files to dockerize the application: a Dockerfile and a .dockerignore file.

COPY

touch Dockerfile .dockerignore docker-compose.yml

.dockerignore

A .dockerignore file is used to tell Docker which files and directories to ignore when building the image.

If you are familiar with the .gitignore file, it works the same way.

Open the file ".dockerignore" and populate it like that:

COPY

node_modules

dist

.git

This will tell Docker to ignore the node_modules, dist and .git directories when building the image.

Dockerfile

A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image.

Open the file "Dockerfile" and populate it like that:

COPY

FROM node:16

WORKDIR /app

COPY package*.json ./

RUN npm install

COPY . .

RUN npm run build

EXPOSE 3000

CMD ["npm", "run", "start:prod"]

Explanation:

FROM node:16 is used to tell Docker which image to use as a base image.

WORKDIR is the directory where the commands will be executed. In our case, it's the /app directory.

COPY package*.json is used to copy the package.json and package-lock.json files to the /app directory.

RUN npm install is used to install the dependencies.

COPY . . is used to copy all the files from the current directory to the /app directory.

RUN npm run build is used to build the application.

EXPOSE is used to expose the port 3000 to the host.

CMD is used to execute a command when the container is started, in our case, it's "npm run start:prod".

docker-compose.yml file

We will use docker compose to run the application and the database.

Populate the file "docker-compose.yml" like that:

COPY

COPY

version: '3.9'

services:

nestapp:

container_name: nestapp

image: francescoxx/nestapp:1.0.0

build: .

ports:

- '3000:3000'

environment:

- DB_TYPE=postgres

- PG_USER=postgres

- PG_PASSWORD=postgres

- PG_DB=postgres

- PG_PORT=5432

- PG_HOST=db

depends_on:

- db

db:

container_name: db

image: postgres:12

environment:

POSTGRES_USER: postgres

POSTGRES_PASSWORD: postgres

POSTGRES_DB: postgres

ports:

- '5432:5432'

volumes:

- pgdata:/var/lib/postgresql/data

volumes:

pgdata: {}

Explanation:

We are using the version 3.9 of the docker-compose.yml file format

We are defining 2 services: nestapp and db

The nestapp service is used to run the NestJS application

The db service is used to run the Postgres database

The nestapp service depends on the db service, so that the db service is started before the nestapp service

For the nestapp service:

container_name is used to set the name of the container

image is used to set the image to use, in our case, it's francescoxx/nestapp:1.0.0 change francescoxxx with your docker hub username

build is used to build the image from the Dockerfile. we are using the current directory as the build context.

ports is used to expose the port 3000 to the host

environment is used to set the environment variables: DB_TYPE, PG_USER, PG_PASSWORD, PG_DB, PG_PORT, PG_HOST. these variables will be used by the application to connect to the database

depends_on is used to tell docker-compose that the db service must be started before the nestapp service.

For the db service:

container_name is used to set the name of the container

image is used to set the image to use, in our case, it's postgres:12

environment is used to set the environment variables: POSTGRES_USER, POSTGRES_PASSWORD, POSTGRES_DB

ports is used to expose the port 5432 to the host

volumes is used to mount a volume to the container. In our case, we are mounting the pgdata volume to the /var/lib/postgresql/data directory.

We also define the pgdata volume at the end of the file.

Run the Postgres service

To run the Postgres service, we will use the docker-compose command.

COPY

docker compose up -d db

This will run the db service in detached mode.

To check if the service is running, we can use the docker ps command:

COPY

docker ps -a

We should see something like that:

$ docker ps -a

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES

e045f74a36ca postgres:12 "docker-entrypoint.s…" 23 seconds ago Up 22 seconds 0.0.0.0:5432->5432/tcp db

But let's check it with TablePlus. Open the TablePlus application and connect to the database, by creating a new "Postgres" connection.

You can use the UI and set:

Host: localhost

Port: 5432

Username: postgres

Password: postgres

Database: postgres

Then hit the "Connect" button at the bottom-right.

TablePlus application

Now we are ready to build the Nest app image and run the application.

Build the Nest app image

To build the Nest app image, we will use the docker compose command.

COPY

docker compose build

This will build the image from the Dockerfile.

To check if the image is built, we can use the docker images command:

$ docker images

REPOSITORY TAG IMAGE ID CREATED SIZE

francescoxx/nestapp 1.0.0 53267c897590 About an hour ago 1.16GB

postgres 12 1db9fa309607 44 hours ago 373MB

Run the Nest app service

To run the Nest app service, we will use the docker-compose command.

COPY

docker compose up

Test the application

To Test the application, we can use the Postman or any other API client.

First of all let's test if the app is running. Open Postman and create a new GET request.

Postman Get request to localhost:3000

Get all users

To get all users, we can make a GET request to localhost:3000/users.

If we see an empty array it means that its working.

Postman Get request to localhost:3000/users

Create a user

To create a user, we can make a POST request to localhost:3000/users.

In the body, we can use the raw JSON format and set the following data:

COPY

{

"name": "aaa",

"email": "aaa@mail"

}

Postman Post request to localhost:3000/users

You can create 2 more users with the following data:

COPY

{

"name": "bbb",

"email": "bbb@mail"

}

COPY

{

"name": "ccc",

"email": "ccc@mail"

}

Get all the three users

To get all the three users, we can make a GET request to localhost:3000/users.

Postman Get request to localhost:3000/users

Get a user by id

To get a single user, we can make a GET request to localhost:3000/users/2.

Postman Get request to localhost:3000/users/2

Update a user

To update a user, we can make a PUT request to localhost:3000/users/2.

Let's change the name from "bbb" to "Francesco" and the email from "bbb@mail" to "francesco@mail".

COPY

{

"name":"Francesco",

"email":"francesco@mail"

}

Postman PUT request to localhost:3000/users/2

Delete a user

Finally, to delete a user, we can make a DELETE request to localhost:3000/users/3.

Postman DELETE request to localhost:3000/users/3

The answer comes directly from the database.

Final test with TablePlus

Let's check if the data is correctly stored in the database.

As a final test, let's return to TablePlus and check if the data has been updated.

TablePlus application

🏁 Conclusion

We made it! We have built a CRUD rest API in TypeScript, using:

NestJS (NodeJS framework)

TypeORM (ORM: Object Relational Mapper)

Postgres (relational database)

Docker (for containerization)

Docker Compose

If you prefer a video version:

Youtube thumbnail of TypeScript CRUD Rest API, using: Nest.js, TypeORM, Postgres, Docker and Docker Compose

All the code is available in the GitHub repository (link in the video description): youtube.com/live/gqFauCpPSlw

That's all.

If you have any question, drop a comment below.

Francesco

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