GraphQL + Apollo Server

Perfect — let’s go through GraphQL with Apollo Server in Node.js, which is essential for building flexible, type-safe APIs.

1️⃣ What is GraphQL?

GraphQL = query language and runtime for APIs
Allows clients to request exactly the data they need
Benefits over REST:
- No over-fetching or under-fetching
- Single endpoint for all data
- Strongly typed schema
- Self-documenting

2️⃣ Apollo Server

Popular Node.js GraphQL server implementation
Works with Express, Koa, Fastify
Supports schema definition, resolvers, subscriptions, and middleware

Install

npm install apollo-server graphql

3️⃣ Basic Apollo Server Setup

const { ApolloServer, gql } = require("apollo-server");
 
// Define schema
const typeDefs = gql`
  type User {
    id: ID!
    name: String!
    email: String!
  }
 
  type Query {
    users: [User]
  }
 
  type Mutation {
    addUser(name: String!, email: String!): User
  }
`;
 
// Sample data
const users = [];
 
// Define resolvers
const resolvers = {
  Query: {
    users: () => users,
  },
  Mutation: {
    addUser: (_, { name, email }) => {
      const newUser = { id: users.length + 1, name, email };
      users.push(newUser);
      return newUser;
    },
  },
};
 
// Create Apollo Server
const server = new ApolloServer({ typeDefs, resolvers });
 
// Start server
server.listen(4000).then(({ url }) => {
  console.log(`🚀 Server ready at ${url}`);
});

Run and navigate to http://localhost:4000 to use GraphQL Playground
Allows testing queries and mutations interactively

4️⃣ Example Queries & Mutations

Query

query {
  users {
    id
    name
    email
  }
}

Mutation

mutation {
  addUser(name: "Tyson", email: "tyson@example.com") {
    id
    name
  }
}

5️⃣ Integration with Express

const express = require("express");
const { ApolloServer } = require("apollo-server-express");
 
const app = express();
 
const server = new ApolloServer({ typeDefs, resolvers });
await server.start();
 
server.applyMiddleware({ app, path: "/graphql" });
 
app.listen(3000, () => console.log("Server running at http://localhost:3000/graphql"));

Allows using GraphQL alongside REST routes

6️⃣ Advanced Features

Subscriptions → real-time updates over WebSockets
Schema stitching / Federation → combine multiple GraphQL APIs
Middleware / Context → inject auth, loaders, or DB connections
DataLoader → batch and cache requests to optimize DB access

7️⃣ Key Takeaways

GraphQL gives flexible, type-safe queries
Apollo Server simplifies server setup and schema management
Resolvers separate data fetching logic from schema
Integrates easily with Express for hybrid apps
Supports mutations, subscriptions, and middleware for advanced use cases

Next, we could cover WebSockets + GraphQL subscriptions for real-time APIs or combining GraphQL with service/repository patterns for a scalable architecture.

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