In this post I will show you how to implement NestJS😻 with GraphQL in code first mode, using Mercurius and the "platform" to Fastify.
For those unfamiliar with NestJS, it's a Node.js TypeScript framework that helps you build efficient and scalable enterprise-grade Node.js applications.
While for those unfamiliar with GraphQL it is a powerful query language for APIs and a runtime to satisfy those queries with existing data. It's an elegant approach that solves many typical REST API problems.
Mercurius, on the other hand, is a GraphQL adapter for Fastify (for others information see the documentation here).
I attach here the link to see the difference between GraphQL vs REST.
The ways to use GraphQL are two first the code or first the schema, the first from the code we create the schema for GraphQL while the second we create our schema that interfaces with GraphQL
In this example we are going to see the code first mode with the use of TypeORM, but you can use whatever you like.
Well now after this short intro let's get started!
So let's get started by creating the NestJS app
Open Terminal and install CLI for NestJS, if you have already installed it, skip this step.
$ npm i -g @nestjs/cli
Then create a NestJS project.
$ nest new nestjs-graphql-mercurius-code-first
$ cd nestjs-graphql-mercurius-code-first
// start the application
$ npm run start:dev
Open the browser on localhost:3000 to verify that hello world is displayed.
Well, the first thing to do before installing the dependencies for graphql and mercurius is to install the @nestjs/platform-fastify package instead of the default express-based @nestjs/platform-express package, because mercurius works with Fastify and not with Express, to do so follow these steps:
npm remove @nestjs/platform-express
and install the dependency for Fastify
npm install @nestjs/platform-fastify
We now modify the file main.ts, configuring the adapter for Fastify within the boostrap function, like this:
import { NestFactory } from '@nestjs/core';
import {
FastifyAdapter,
NestFastifyApplication,
} from '@nestjs/platform-fastify';
import { AppModule } from './app.module';
async function bootstrap() {
const app = await NestFactory.create<NestFastifyApplication>(
AppModule,
new FastifyAdapter()
);
await app.listen(3000);
}
bootstrap();
now we open the browser again on localhost:3000 or via curl (curl -H 'content-type: application/json' -v -X GET http://127.0.0.1:3000) to verify that "hello world" is displayed.
Good! Now let's proceed with configuring the database with docker by creating a docker-compose.yml file to create the PostgreSQL service, things follows:
services:
db:
image: postgres
restart: always
ports:
- "5432:5432"
environment:
POSTGRES_USER: postgres
POSTGRES_PASSWORD: pass123
POSTGRES_DB: postgres
for those who do not know what docker is I leave you the link here for more information: https://www.docker.com/get-started
There are many different ways to integrate Nest with databases, and all of them depend on personal preferences or project needs.
Install graphql dependencies and devDependencies
$ npm i @nestjs/graphql @nestjs/mercurius graphql mercurius
Create a GraphqlOptions class for GraphQL settings, as follows:
import { GqlOptionsFactory } from '@nestjs/graphql';
import { Injectable } from '@nestjs/common';
import { MercuriusDriverConfig } from '@nestjs/mercurius';
@Injectable()
export class GraphqlOptions implements GqlOptionsFactory {
createGqlOptions(): Promise<MercuriusDriverConfig> | MercuriusDriverConfig {
return {
autoSchemaFile: 'src/schema.gql',
subscription: true,
graphiql: true,
};
}
}
An important thing about this configuration and set where we want the schema.gql file to be generated, you can call it whatever you want, the important thing is to prefix it with *.gql.
Well now let's move on to registering GraphQLModule in AppModule:
@Module({
imports:[
GraphQLModule.forRootAsync<MercuriusDriverConfig>({
driver: MercuriusDriver,
useClass: GraphqlOptions,
}),
],
})
export class AppModule {}
Well, now let's move on to installing dependencies for Typeorm.
Install TypeORM and PostgreSQL dependencies
$ npm install --save @nestjs/typeorm typeorm pg
We also install another package for configuration files such as .env files (environments)
$ npm install --save @nestjs/config
Set TypeOrmModule and ConfigModule in AppModule
import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
@Module ({
imports: [
ConfigModule.forRoot(),
TypeOrmModule.forRootAsync({
useFactory: () => ({
type: 'postgres',
host: process.env.DATABASE_HOST,
port: +process.env.DATABASE_PORT,
username: process.env.DATABASE_USER,
password: process.env.DATABASE_PASSWORD,
database: process.env.DATABASE_NAME,
autoLoadEntities: true,
synchronize: true,
}),
}),
],
})
export class AppModule {}
Create a .env file, as follows:
DATABASE_HOST=localhost
DATABASE_USER=postgres
DATABASE_PASSWORD=pass123
DATABASE_NAME=postgres
DATABASE_PORT=5432
If you have trouble setting up TypeOrmModule here, make sure Docker is running with docker compose up.
Also make sure the database name inside your .env matches the one you have in your docker-compose file.
Well now let's create our entity we call it users.entity.ts:
import {
Entity,
PrimaryGeneratedColumn,
Column,
} from 'typeorm';
import { Field, ID, ObjectType } from '@nestjs/graphql';
@Entity()
@ObjectType()
export class Users {
@Field(() => ID)
@PrimaryGeneratedColumn()
id: number;
@Field()
@Column()
name: string;
@Field()
@Column()
username: string;
@Field()
@Column()
email: string;
@Field()
@Column({ length: 60 })
password: string;
}
Create Data Transfer Objects (Dto) class to create the user, which we will call CreateUserInput:
import { Field, InputType } from '@nestjs/graphql';
import { IsEmail, IsNotEmpty, IsString, MaxLength } from 'class-validator';
@InputType()
export class CreateUserInput {
@Field()
@IsString()
readonly name: string;
@Field()
@IsEmail()
readonly email: string;
@Field()
@IsString()
@MaxLength(40)
readonly username: string;
@Field()
@IsNotEmpty()
@IsString()
@MaxLength(60)
password: string;
}
Remember to install this package before creating the dto class for the upgrade.
$ npm i @nestjs/mapped-types
Well, now to update the user data we extend the CreateUserInput class:
import { InputType, PartialType } from '@nestjs/graphql';
import { CreateUserInput } from './create-user.input';
@InputType()
export class UpdateUserInput extends PartialType(CreateUserInput) {}
we call validation pipe in the main.ts file as follows:
import { ValidationPipe } from '@nestjs/common';
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
async function bootstrap() {
const app = await NestFactory.create(AppModule);
app.useGlobalPipes(
new ValidationPipe({
whitelist: true,
transform: true,
forbidNonWhitelisted: true,
transformOptions: {
enableImplicitConversion: true,
},
}),
);
await app.listen(3000);
}
bootstrap();
Well, now we're going to create a simple service, resolver, and user module
$ nest g module users
$ nest g service users
$ nest g resolver users
You should now have a users folder with UsersModule, UsersService, and UsersResolver inside.
Now before we write our service, let's create a final dto file for the pagination, as follows:
import { ArgsType, Field, Int } from '@nestjs/graphql';
import { Max, Min } from 'class-validator';
@ArgsType()
export class UsersArgs {
@Field(() => Int)
@Min(0)
offset = 0;
@Field(() => Int)
@Min(1)
@Max(50)
limit = 25;
}
Now let's start writing our UsersService:
import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import * as bcrypt from 'bcrypt';
import { Repository } from 'typeorm';
import { CreateUserInput } from './dto/create-user.input';
import { UpdateUserInput } from './dto/update-user.input';
import { UsersArgs } from './dto/users.args';
import { Users } from './entities/users.entity';
import { ErrorWithProps } from 'mercurius';
@Injectable()
export class UsersService {
constructor(
@InjectRepository(Users)
private readonly usersRepository: Repository<Users>,
) {}
public async findAll(usersArgs: UsersArgs): Promise<Users[]>
{
const { limit, offset } = usersArgs;
return this.usersRepository.find({
skip: offset,
take: limit,
});
}
public async findOneById(id: string): Promise<Users> {
const user = await this.usersRepository.findOne(id);
if (!user) {
throw new ErrorWithProps(`User #${id} not found`);
}
return user;
}
public async create(createUserInput: CreateUserInput): Promise<Users> {
createUserInput.password = bcrypt.hashSync(createUserInput.password, 8);
const user = this.usersRepository.create({ ...createUserInput});
return this.usersRepository.save(user);
}
public async update(
id: string,
updateUserInput: UpdateUserInput,
): Promise<Users> {
updateUserInput.password = bcrypt.hashSync(updateUserInput.password, 8);
const user = await this.usersRepository.preload({
id: +id,
...updateUserInput,
});
if (!user) {
throw new ErrorWithProps(`User #${id} not found`);
}
return this.usersRepository.save(user);
}
public async remove(id: string): Promise<any> {
const user = await this.findOneById(id);
return this.usersRepository.remove(user);
}
}
UserResolver:
import { Args, Mutation, Query, Resolver } from '@nestjs/graphql';
import { CreateUserInput, UpdateUserInput, UsersArgs } from './dto';
import { UsersService } from './users.service';
import { Users } from './entities/users.entity';
import { ErrorWithProps } from 'mercurius';
@Resolver()
export class UsersResolver {
constructor(private readonly usersService: UsersService) {}
@Query(() => [Users])
public async users(@Args() usersArgs: UsersArgs): Promise<Users[]> {
return this.usersService.findAll(usersArgs);
}
@Query(() => Users)
public async user(@Args('id') id: string): Promise<Users> {
const user = await this.usersService.findOneById(id);
if (!user) {
throw new ErrorWithProps(`User #${id} not found`);
}
return user;
}
@Mutation(() => Users)
public async createUser(
@Args('createUserInput') createUserInput: CreateUserInput,
): Promise<Users> {
return await this.usersService.create(createUserInput);
}
@Mutation(() => Users)
public async updateUser(
@Args('id') id: string,
@Args('updateUserInput') updateUserInput: UpdateUserInput,
): Promise<Users> {
return await this.usersService.update(id, updateUserInput);
}
@Mutation(() => Users)
public async removeUser(@Args('id') id: string): Promise<any> {
return this.usersService.remove(id);
}
}
Now register in our UsersModule our service and the resolver, like this:
import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
import { UsersService } from './users.service';
import { UsersResolver } from './users.resolver';
import { Users } from './entities/users.entity';
@Module({
imports: [TypeOrmModule.forFeature([Users])],
providers: [UsersService, UsersResolver],
})
export class UsersModule {}
Well now let's try to interact with GraphQL to see if everything works, but before we have to verify that starting our application the schema.gql file is generated, once done, from the browser we go to the address http://localhost:3000/graphiql thus starting our GraphiQL ( the Graphql Playground for Mercurius), a UI that allows us to interact with our database.
I add below the Queries and Mutations to run in the GraphiQL:
getUsers
{
users {
id
name
email
username
password
}
}
getUserById
{
user(id: "1") {
id
name
email
username
password
}
}
addUser
mutation {
createUser(createUserInput: {
name: "tony"
email:"tony_admin@nest.it"
username: "tony_admin"
password: "secret123"
}) {
name
email
username
password
}
}
updateUser
mutation {
updateUser(
updateUserInput: {
name: "tony"
email: "tony_admin@nest.it"
username: "tony_admin"
password: "secret123"
}
id: "1"
) {
name
email
username
password
}
}
removeUser
mutation {
removeUser(id: "3") {
name
email
username
password
}
}
That's all.
I hope it will be helpful for anything write me in the comments as well.😉
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