GraphQL with TypeScript – `type-graphql`

Install dependencies

npm i type-graphql graphql reflect-metadata
npm i -D @types/node

Add import 'reflect-metadata'; at the entry point.

Define a resolver

import { Resolver, Query, Arg, Mutation, ObjectType, Field, ID } from 'type-graphql';

@ObjectType()
class User {
  @Field(() => ID)
  id!: number;

  @Field()
  name!: string;
}

@Resolver(User)
class UserResolver {
  private users: User[] = [];

  @Query(() => [User])
  allUsers() { return this.users; }

  @Mutation(() => User)
  createUser(@Arg('name') name: string): User {
    const user = { id: Date.now(), name } as User;
    this.users.push(user);
    return user;
  }
}

Bootstrap server

import { ApolloServer } from 'apollo-server';
import { buildSchema } from 'type-graphql';

async function bootstrap() {
  const schema = await buildSchema({ resolvers: [UserResolver] });
  const server = new ApolloServer({ schema });
  const { url } = await server.listen(4000);
  console.log(`🚀 GraphQL ready at ${url}`);
}
bootstrap();