2-configure-database.md

Index

• 1. PostgreSQL

  • 1.1 Docker compose

• 2. Adminer

  • 2.1 Docker compose

  • 2.2 Connect to your database

• 3. Prisma

  • 3.1 Install Prisma

  • 3.2 Create Prisma schema

  • 3.3 Generate Prisma client

    • 3.3.1 Prisma Module

    • 3.3.2 Prisma Service

  • 3.3 Migrate your database

  • 3.4 Seed your database

• Previous Docs : Install and Create Nest project

• Next Docs: Database Schema

---

Configure PostgreSQL

Docker compose

• Set your environment variables in your .env file
• Add this to your docker-compose.yml

  db:
    image: postgres:15.1-alpine
    container_name: transcendence-db
    restart: always
    environment:
      - POSTGRES_HOST=${POSTGRES_HOST}
      - POSTGRES_PORT=${POSTGRES_PORT}
      - POSTGRES_DB=${POSTGRES_DB}
      - POSTGRES_USER=${POSTGRES_USER}
      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
    volumes:
      - 'data:/var/lib/postgresql/data'
    expose:
      - '5432'
    networks:
      - transcendence

Configure Adminer

Docker compose

  adminer:
    image: adminer
    container_name: transcendence-adminer
    restart: always
    environment:
      - ADMINER_DEFAULT_SERVER=db
    ports:
      - '8080:8080'
    networks:
      - transcendence

Connect to your database

• In your docker-compose.yml, you have to set the environment variable ADMINER_DEFAULT_SERVER to the name of your database service (here db)
• Go to http://localhost:8080
• Connect with your database credentials, you should be able to see your database

Prisma

Install Prisma

• You should check the official documentation which is very well done
• In your nest project, install prisma

npm install prisma --save-dev

• Initialize prisma

npx prisma init

• You should have a new folder prisma with a schema.prisma file inside
• Think about adding the DATABASE_URL environment variable in your backend container

DATABASE_URL="postgres://myuser:mypassword@localhost:5432/db"

Prisma schema

• You can find the documentation here
• First, you have to define your database connection

generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

• Then, you can define your models

model User {
  id        Int      @id @default(autoincrement())
  email     String   @unique
  name      String?
  posts     Post[]
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt
}

• You can also define relations between your models

model Post {
  id        Int      @id @default(autoincrement())
  title     String
  content   String?
  published Boolean  @default(false)
  author    User?    @relation(fields: [authorId], references: [id])
  authorId  Int?
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt
}

• Your prisma.schema file will be used to generate your database schema, and so need to contain all the information about your database

Prisma client

• You need to generate your prisma client to be able to use it in your nest project

npm install @prisma/client

Install Prisma for NestJS

• There is a simple example here
• You need to create a PrismaService and a PrismaModule

Prisma Module

import { Module } from '@nestjs/common';
import { PrismaService } from './prisma.service';

/**
 * Any module that imports the PrismaModule will have access to PrismaService
 */
@Module({
  providers: [PrismaService],
  exports: [PrismaService],
})
export class PrismaModule {}

• Think about add it in your app.module.ts

Prisma Service

• Here is a simple example of a PrismaService

import { INestApplication, Injectable, OnModuleInit } from '@nestjs/common';
import { PrismaClient } from '@prisma/client';


@Injectable()
export class PrismaService extends PrismaClient implements OnModuleInit {
  async onModuleInit() {
    await this.$connect();
  }

  /**
   * Ensure application shuts down gracefully.
   */
  async enableShutdownHooks(app: INestApplication) {
    this.$on('beforeExit', async () => {
      await app.close();
    });
  }
}

Migration

• You can find the documentation here
• If you want to update your database schema, you need to create a migration file that will be created in the prisma/migrations folder on schema changes
• You can then apply your migration directly in your container

npx prisma migrate dev

• You can also use npx prisma migrate deploy to apply all migrations

Seed your database

• You should think about seeding your database with some data to test your application
• This article explains how to do it
• You need to create a seed.ts file in your prisma folder
• You can then run npx prisma db seed --preview-feature to seed your database

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