Description

TypeScript-NestJS-GraphQL Code First Repository.

Installation

Install NestJS if not installed already

npm i -g @nestjs/cli

Create the NestJS application

nest new graphql-codefirst-nest

REQUIRED: Change to the project directory

OPTIONAL: Run the Nest Application to test if everything is working fine.

Install the required NPM packages

npm i --save @nestjs/typeorm typeorm mysql dotenv
npm i --save @nestjs/graphql graphql-tools graphql
npm i --save apollo-server-express @nestjs/common

Enable the GraphQL code first approach

Enter the following code in app.module.ts under imports[]

GraphQLModule.forRoot({
      autoSchemaFile: 'schema.gql',
      debug: false,
      playground: true,
    }),

Prepare the Environment

Create the .env file with required key-value pairs, the following is the minimal required environment variables for this project.

APP_PORT=3001
DB_HOST=localhost
DB_PORT=3306
DB_USERNAME=root
DB_PASSWORD=***********
DB_NAME=jobs-db
DB_SYNC=false

Add TypeORM to the project

Use the following to read the .env file correctly

require('dotenv').config();

Enter the following code in app.module.ts under imports[],

TypeOrmModule.forRoot({
      type: 'mysql',
      host: process.env.DB_HOST,
      port: +process.env.DB_PORT,
      username: process.env.DB_USERNAME,
      password: process.env.DB_PASSWORD,
      database: process.env.DB_NAME,
      entities: ['dist/**/*.model.js'],
      synchronize: process.env.DB_SYNC === 'true' ? true : false,
    }),

At this point compiling the project would result in the error since there is no graphql schema is defined. The purpose of the code first approach is to auto-generate this required file automatically based on the code we develop further.

IF YOU GET THIS ERROR

Error: ER_NOT_SUPPORTED_AUTH_MODE: Client does not support authentication protocol requested by server; consider upgrading MySQL client

CONSIDER ADDING THE USER AN ACCESS TO YOUR DATABASE

Development

Step1: Generate Required Artifacts and Reference them in App Module

Step2: Create data models for TypeORM and GraphQL Entity mapping.

Step3: Implement the resolvers and services with required API operations.

Generate Required Resolvers, Services, and Modules

nest g resolver company --no-spec
nest g resolver employee --no-spec
nest g service company --no-spec
nest g service employee --no-spec
nest g module company
nest g module employee

The above command should generate required skeleton files under the directory named same as the module name.

Update the Company Module with the following code and reference correctly.

@Module({
  imports: [TypeOrmModule.forFeature([CompanyModel])],
  providers: [CompanyService, CompanyResolver],
  exports: [CompanyService],
})
export class CompanyModule {}

Update the Employee Module with the following code and reference correctly.

@Module({
  imports: [TypeOrmModule.forFeature([EmployeeModel])],
  providers: [EmployeeService, EmployeeResolver],
  exports: [EmployeeService],
})
export class EmployeeModule {}

Update the App Module with the Company and Employee Module reference under the imports[].

The updated App Module should look like

@Module({
  imports: [
    TypeOrmModule.forRoot({
      type: 'mysql',
      host: process.env.DB_HOST,
      port: +process.env.DB_PORT,
      username: process.env.DB_USERNAME,
      password: process.env.DB_PASSWORD,
      database: process.env.DB_NAME,
      entities: ['dist/**/*.model.js'],
      synchronize: process.env.DB_SYNC === 'true' ? true : false,
    }),
    GraphQLModule.forRoot({
      autoSchemaFile: 'schema.gql',
      debug: false,
      playground: true,
    }),
    EmployeeModule,
    CompanyModule,
  ],
  controllers: [],
  providers: [],
})
export class AppModule {}

Add Database Model and GraphQL Entity Support

+ Create the company.model.ts file under the company directory, add and export the class CompanyModel from within the file.

+ Create the employee.model.ts file under the employee directory, add and export the class EmployeeModel from within the file.

+ Add column/field names of the company and employee tables respectively in above classes.

+ Mark them with the @Field() decorator for the GraphQL schema generation

+ Mark them with the @Column() decorator for the TypeORM support

+ OPTIONAL: Add TypeORM @JoinColumn() and OneToMany()/@ManyToOne() relation decorators, if the APIs needs to fetch the nested/related data.

The updated company.model.ts file should look as under, check the source code for employee.model.ts for the counter part.

@ObjectType()
@Entity('company')
export class CompanyModel {
  @Field()
  @PrimaryGeneratedColumn()
  id: number;

  @Field({ name: 'name' })
  @Column('varchar', { length: 50, nullable: false })
  name: string;

  @Field(type => [EmployeeModel], { nullable: true })
  @OneToMany(
    type => EmployeeModel,
    employee => employee.company,
    { lazy: true },
  )
  @JoinColumn({ name: 'id' })
  employees: EmployeeModel[];
}

NOTE that the class is decorated with @ObjectType() and @Entity(). Specify the table name to the @Entity decorator to correctly generate the query by TypeORM.

For GraphQL to map the data correctly with other relational entities (TypeORM Entities) it is mandatory to specify the { lazy: true }, attribute in the relations, Otherwise the result will always return null.

Implement the Resolvers and Services

+ Inject the service reference in the resolver classes

+ Add the endpoints and implement the service counter parts

The implemented company.resolver.ts looks like

@Resolver(of => CompanyModel)
export class CompanyResolver {
  constructor(@Inject(CompanyService) private CompanyService: CompanyService) {}

  @Query(returns => CompanyModel)
  async Company(@Args('id') id: string): Promise<CompanyModel> {
    return await this.CompanyService.findOneCompany(id);
  }

  @Query(returns => CompanyModel)
  async Companies(): Promise<CompanyModel[]> {
    return await this.CompanyService.findAllCompanies();
  }
}

The implemented company.service.ts looks like

@Injectable()
export class CompanyService {
  constructor(
    @InjectRepository(CompanyModel)
    private CompanyRepository: Repository<CompanyModel>,
  ) {}

  findOneCompany(id: string): Promise<CompanyModel> {
    return this.CompanyRepository.findOne(id);
  }

  findAllCompanies(): Promise<CompanyModel[]> {
    return this.CompanyRepository.find();
  }
}

Check the source code for employee.resolver.ts and employee.service.ts for the counter part.

Seed the data (For now)

Import the seed data into the MySQL tables

Build and test the project

npm run build
OR
nest build

The above command will build the project and generate a dist directory.

npm run start
OR
nest start

The above command will start the Nest Application and the GraphQL Playground can be accessed at following URL.

http://localhost:3001/graphql

Company API

Employee API

ToDo

This project is a boilerplate code for anyone to start with the Code First NestJS and GraphQL APIs using TypeORM. The following thing are still needs to be implemented.

• Add other CRUD operations
• Add exception handling
• Add validations