Apollo Server setup in GraphQL

Introduction

Apollo Server helps you create a GraphQL API easily. It connects your data to clients in a simple way.

You want to build a flexible API for your app or website.

You need to fetch data from a database and send only what clients ask for.

You want to combine data from different sources into one API.

You want to test and explore your API with a friendly interface.

You want to add real-time updates with subscriptions.

Syntax

GraphQL

import { ApolloServer } from '@apollo/server';

const typeDefs = `
  type Query {
    hello: String
  }
`;

const resolvers = {
  Query: {
    hello: () => 'Hello world!'
  }
};

const server = new ApolloServer({ typeDefs, resolvers });

await server.start();

// Then connect server to your HTTP framework (like Express or Fastify)

typeDefs defines the data types and queries clients can ask.

resolvers tell the server how to get the data for each query.

Examples

This example changes the query name to greeting and returns a different message.

GraphQL

const typeDefs = `
  type Query {
    greeting: String
  }
`;

const resolvers = {
  Query: {
    greeting: () => 'Hi there!'
  }
};

This example shows a query that returns a number instead of text.

GraphQL

const typeDefs = `
  type Query {
    number: Int
  }
`;

const resolvers = {
  Query: {
    number: () => 42
  }
};

Sample Program

This program sets up a simple Apollo Server with one query called hello. When you run it, the server is ready to answer with 'Hello world!'.

GraphQL

import { ApolloServer } from '@apollo/server';

const typeDefs = `
  type Query {
    hello: String
  }
`;

const resolvers = {
  Query: {
    hello: () => 'Hello world!'
  }
};

const server = new ApolloServer({ typeDefs, resolvers });

await server.start();

console.log('Apollo Server is ready to handle requests.');

Important Notes

You need to connect Apollo Server to an HTTP server like Express or Fastify to handle real requests.

Always start the server with await server.start() before using it.

Use GraphQL playground or Apollo Studio to test your queries easily.

Summary

Apollo Server makes creating GraphQL APIs simple and fast.

Define your data structure with typeDefs and how to get data with resolvers.

Start the server and connect it to your web server to serve client requests.