Simple example GraphQL(Code First) with NestJS 7.x/8.x 😻

In this post I will show you how to implement NestJS😻 with GraphQL, in code first mode.
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.

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 nestj-api-graphql-code-first
$ cd nestj-api-graphql-code-first
// start the application
$ npm run start:dev

Open the browser on localhost:3000 to verify that hello world is displayed.

then we create a docker-compose.yml file for create service PostgreSQL

version: "3"
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 graphql [email protected]

Create a GraphqlOptions class for GraphQL settings, as follows:

import { GqlOptionsFactory, GqlModuleOptions } from '@nestjs/graphql';
import { Injectable } from '@nestjs/common';

@Injectable()
export class GraphqlOptions implements GqlOptionsFactory {
  createGqlOptions(): Promise<GqlModuleOptions> | GqlModuleOptions {
    return {
      installSubscriptionHandlers: true,
      autoSchemaFile: 'src/schema.gql',
    };
  }
}

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({
    GraphQLModule.forRootAsync({
      useClass: GraphqlOptions,
    }),
})
export class AppModule {}

Well, now let's move on to installing dependencies for Typeorm.

Install TypeORM and MySQL dependencies

$ npm install --save @nestjs/typeorm typeorm mysql

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, NotFoundException } 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';

@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 NotFoundException(`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 NotFoundException(`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 { NotFoundException } from '@nestjs/common';
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';

@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 NotFoundException(id);
    }
    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/graphql
thus starting our GraphQL Playground, a UI that allows us to interact with our database.

I add below the Queries and Mutations to run in the GraphQL Playground:

getUsers

{
    users {
        id
        name
        email
        username
        password
    }
}

getUserById

{
    user(id: "1") {
        id
        name
        email
        username
        password
    }
}

addUser

mutation {
    createUser(createUserInput: {
        name: "tony"
        email:"[email protected]"
        username: "tony_admin"
        password: "secret123"
    }) {
        name
        email
        username
        password
    }
}

updateUser

mutation {
    updateUser(
        updateUserInput: {
            name: "tony"
            email: "[email protected]"
            username: "tony_admin"
            password: "secret123"
        }
        id: "1"
    ) {
        name
        email
        username
        password
    }
}

removeUser

mutation {
    removeUser(id: "3") {
        name
        email
        username
        password
    }
}

Now I leave it to you to create a module for posts and a role module for users.

That's all.

I hope it will be helpful for anything write me in the comments as well.😉

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