GraphQL Server Setup in GraphQL

// Install dependencies
npm install @apollo/server @as-integrations/express4 graphql graphql-tag express cors

// Basic GraphQL server with Apollo
const { ApolloServer } = require('@apollo/server');
const { expressMiddleware } = require('@as-integrations/express4');
const { gql } = require('graphql-tag');
const express = require('express');
const cors = require('cors');

// Type definitions (Schema)
const typeDefs = gql`
  type Query {
    hello: String
    users: [User!]!
    user(id: ID!): User
  }
  
  type User {
    id: ID!
    name: String!
    email: String!
    posts: [Post!]!
  }
  
  type Post {
    id: ID!
    title: String!
    content: String!
    author: User!
  }
`;

// Resolvers
const resolvers = {
  Query: {
    hello: () => 'Hello World!',
    users: () => users,
    user: (parent, args) => users.find(u => u.id === args.id)
  },
  User: {
    posts: (parent) => posts.filter(p => p.authorId === parent.id)
  }
};

// Create server
async function startServer() {
  const app = express();
  const server = new ApolloServer({ typeDefs, resolvers });
  
  await server.start();
  app.use('/graphql', cors(), express.json(), expressMiddleware(server));
  
  app.listen(4000, () => {
    console.log('Server running at http://localhost:4000/graphql');
  });
}

startServer();