nest-advanced

NestJS Advanced Surfaces

This skill covers the three advanced surfaces NestJS supports beyond REST. Each is opt-in via package presence — do not introduce these surfaces speculatively.

GraphQL (@nestjs/graphql)

Module setup (code-first, modern default)

import { GraphQLModule } from '@nestjs/graphql';
import { ApolloDriver, ApolloDriverConfig } from '@nestjs/apollo';

@Module({
  imports: [
    GraphQLModule.forRoot<ApolloDriverConfig>({
      driver: ApolloDriver,
      autoSchemaFile: 'schema.gql',         // or `true` for in-memory
      sortSchema: true,
      playground: process.env.NODE_ENV !== 'production',
      context: ({ req }) => ({ req }),
    }),
  ],
})
export class AppModule {}

ObjectType (return types)

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

  @Field()
  email!: string;

  @Field({ nullable: true })
  name?: string;

  @Field(() => [Order])
  orders!: Order[];
}

• @Field() — exposes the property; type inferred from TypeScript when possible.
• For arrays/non-primitive types, pass the explicit type: @Field(() => [Order]).
• nullable: true for optional fields; matches TS ?: modifier.

InputType (mutation inputs)

@InputType()
export class CreateUserInput {
  @Field()
  @IsEmail()
  email!: string;

  @Field()
  @MinLength(8)
  password!: string;
}

InputType + class-validator works alongside the global ValidationPipe for runtime checks.

Resolver

@Resolver(() => User)
export class UsersResolver {
  constructor(private readonly users: UsersService) {}

  @Query(() => User, { nullable: true })
  user(@Args('id', { type: () => ID }) id: string) {
    return this.users.findById(id);
  }

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

  @Mutation(() => User)
  createUser(@Args('input') input: CreateUserInput) {
    return this.users.create(input);
  }

  @ResolveField(() => [Order])
  orders(@Parent() user: User) {
    return this.users.ordersByUserId(user.id);
  }
}