Introduction to GraphQL with NestJS
Last Updated :
25 Jul, 2024
NestJS is a progressive NodeJS framework that uses TypeScript to build efficient and scalable server-side applications. Combining NestJS with GraphQL, a powerful query language for APIs, offers a robust solution for creating modern, maintainable, and highly performant web applications. In this article, we'll explore the basics of setting up a GraphQL API with NestJS.
What is GraphQL?
GraphQL is a query language for APIs and a runtime for executing those queries by using a type system you define for your data. It allows clients to request exactly the data they need, making APIs more efficient and flexible.
Setting Up a NestJS Project with GraphQL
To get started, you'll need to have NodeJS and npm installed on your machine. Then, follow these steps to set up a new NestJS project and integrate GraphQL.
Step 1: Install the nestjs cli
npm i -g @nestjs/cli
Step 2: Create a nestjs project
nest new nest-gfg
cd nestgfg
Step 3: Install GraphQL and Apollo Server
npm install @nestjs/graphql @nestjs/apollo graphql apollo-server-express
Folder Structure
NestJS folder StructureDependencies
"dependencies": {
"@nestjs/apollo": "^12.2.0",
"@nestjs/common": "^10.0.0",
"@nestjs/core": "^10.0.0",
"@nestjs/graphql": "^12.2.0",
"@nestjs/mongoose": "^10.0.10",
"@nestjs/platform-express": "^10.0.0",
"apollo-server-express": "^3.13.0",
"class-transformer": "^0.5.1",
"class-validator": "^0.14.1",
"dotenv": "^16.4.5",
"graphql": "^16.9.0",
"mongoose": "^8.5.1",
"reflect-metadata": "^0.2.0",
"rxjs": "^7.8.1"
}
Example: Implementing GraphQL with NestJS
JavaScript
// src/app.resolver.ts
import { Resolver, Query, Args } from '@nestjs/graphql';
import { AppService } from './app.service';
import { ObjectType, Field } from '@nestjs/graphql';
@ObjectType()
class Greeting {
@Field()
message: string;
}
@Resolver()
export class AppResolver {
constructor(private readonly appService: AppService) { }
@Query(() => String)
sayHello(): string {
return this.appService.getHello();
}
@Query(() => Greeting)
getGreeting(@Args('name') name: string): Greeting {
return { message: `Hello, ${name}!` };
}
}
JavaScript
// src/app.service.ts
import { Injectable } from '@nestjs/common';
@Injectable()
export class AppService {
getHello(): string {
return 'Hello World!';
}
}
JavaScript
// src/app.module.ts
import { Module } from '@nestjs/common';
import { GraphQLModule } from '@nestjs/graphql';
import { ApolloDriver, ApolloDriverConfig } from '@nestjs/apollo';
import { join } from 'path';
import { AppService } from './app.service';
import { AppResolver } from './app.resolver';
@Module({
imports: [
GraphQLModule.forRoot<ApolloDriverConfig>({
driver: ApolloDriver,
autoSchemaFile: join(process.cwd(), 'src/schema.gql'),
}),
],
providers: [AppService, AppResolver],
})
export class AppModule { }
To start the appliction run the followingh command
npm run start
Output
Best Practices for GraphQL with NestJS
- Use DTOs and Input Types: Define Data Transfer Objects (DTOs) and input types to validate and type your input data.
- Modular Architecture: Organize your application into modules to keep your codebase maintainable and scalable.
- Error Handling: Implement proper error handling in your resolvers to provide meaningful error messages to the client.
- Authentication and Authorization: Use guards and middleware to protect your GraphQL API endpoints.
Similar Reads
Introduction to Graph Database on NoSQL A graph database is a type of NoSQL database that is designed to handle data with complex relationships and interconnections. In a graph database, data is stored as nodes and edges, where nodes represent entities and edges represent the relationships between those entities. Graph databases are parti
8 min read
Introduction to Apollo Server Traditional REST APIs often struggle with inefficiencies like over-fetching (retrieving more data than needed) and under-fetching (not getting enough data, requiring multiple API calls). This leads to slower applications, unnecessary network requests, and increased complexity in API management. Apol
6 min read
How to Write GraphQL Queries GraphQL queries are a fundamental part of interacting with a GraphQL server, allowing clients to request specific data they need. GraphQL queries are used to fetch or modify data from a GraphQL server. They are written in a syntax similar to JSON and allow clients to specify the exact data they need
4 min read
How to use GraphQL with Postman GraphQL is an open-source technology that allows us to query only the data that we require, unlike the traditional REST architecture which returns us the entire resources and data with specific endpoints configured for the same. Using GraphQL, we specify using the query the data that we want, and it
5 min read
Introspection in GraphQL Introspection in GraphQL is a powerful feature that allows users to understand and query the structure of a GraphQL schema. It enables developers to dynamically explore the available object types, mutations, queries, and fields supported by the server. Introspection plays a crucial role in GraphQL d
5 min read