[Server]: Add GraphQL Support for Enhanced API Flexibility

[NightClover-code]

Description:

GraphQL can be particularly beneficial for our e-commerce application by:

• Reducing over-fetching (clients can request exactly what they need)
• Enabling efficient product browsing with custom field selection
• Allowing complex queries (e.g., products with reviews, related items) in a single request
• Improving mobile app performance through selective data fetching

Current State:

We have a REST API that requires multiple endpoints for related data. For example, to get a product with its reviews and related products requires multiple API calls.

Required Packages:

pnpm add @nestjs/graphql @nestjs/apollo graphql apollo-server-express

Example Product Type Definition:

import { ObjectType, Field, ID, Float } from '@nestjs/graphql';

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

  @Field()
  name: string;

  @Field()
  description: string;

  @Field(() => Float)
  price: number;

  @Field(() => [ReviewType])
  reviews: ReviewType[];

  @Field(() => [ProductType], { nullable: true })
  relatedProducts?: ProductType[];
}

Example Query Resolver:

@Resolver(() => ProductType)
export class ProductResolver {
  constructor(private productsService: ProductsService) {}

  @Query(() => [ProductType])
  async products(
    @Args('keyword', { nullable: true }) keyword?: string,
    @Args('page', { nullable: true }) page?: number,
  ) {
    return this.productsService.findMany(keyword, page?.toString());
  }

  @ResolveField(() => [ProductType])
  async relatedProducts(@Parent() product: ProductType) {
    return this.productsService.findRelated(product.id);
  }
}

Tasks

1. Initial Setup

• Install required packages
• Configure GraphQL module
• Set up Apollo playground
• Add basic health check query
• Document setup in README.md

2: Product GraphQL Types

• Create Product type
• Create Review type
• Create input types for mutations
• Add pagination support
• Add field descriptions

3: Product Queries and Resolvers

• Implement products query
• Add single product query
• Add top rated products query
• Add review field resolver
• Add related products resolver

More GraphQL tasks to be added after first implementation.

Relevant Docs

https://docs.nestjs.com/graphql/quick-start