Graph QL Simple working example

Here's a simple working tutorial on creating a GraphQL server using Node.js and Express, with a basic query and mutation. We'll be using the Apollo Server Express library to create the GraphQL server.

1. Install Node.js: If you don't have Node.js installed, download and install it from the official website: https://nodejs.org/

2. Create a new project folder: Create a new folder for your project and navigate to it in your terminal or command prompt.

3. Initialize the project: Run the following command to initialize a new Node.js project:

npm init -y

4. Install required packages: Install Express, Apollo Server Express, and GraphQL using the following command:

npm install express apollo-server-express graphql

5. Create the GraphQL schema: Create a file named schema.graphql in your project folder and add the following schema definition:

type Query {
  hello: String
}

type Mutation {
  setMessage(message: String!): String
}

Here we define a simple query hello that returns a string and a mutation setMessage that takes a string as input and returns a string.

6. Create the server: Create a file named index.js in your project folder and add the following code:

const express = require("express");
const { ApolloServer, gql } = require("apollo-server-express");
const fs = require("fs");

// Read the schema from the schema.graphql file
const typeDefs = gql(fs.readFileSync("schema.graphql", "utf8"));

// Set up the resolvers
const resolvers = {
  Query: {
    hello: () => "Hello, world!",
  },
  Mutation: {
    setMessage: (_, { message }) => message,
  },
};

// Create the Apollo Server
const server = new ApolloServer({ typeDefs, resolvers });

// Create the Express app
const app = express();

// Apply the Apollo middleware to the Express app
server.applyMiddleware({ app });

// Start the server
const PORT = process.env.PORT || 4000;
app.listen(PORT, () =>
  console.log(`GraphQL server running at http://localhost:${PORT}${server.graphqlPath}`)
);

In this code, we create a simple Express app and an Apollo Server with the schema and resolvers. The hello query returns a static string, and the setMessage mutation returns the input message.

7. Start the server: Run the following command in your terminal or command prompt:

node index.js

Your GraphQL server should now be running at http://localhost:4000/graphql.

8. Test your GraphQL server: Open a web browser and navigate to http://localhost:4000/graphql. You should see the GraphQL Playground interface. Run the following query and mutation in the playground:

query {
  hello
}

mutation {
  setMessage(message: "This is a test message!")
}

You should see the appropriate responses for the query and mutation.

That's it! You now have a simple working GraphQL server using Node.js, Express, and Apollo Server Express. You can expand the schema and resolvers to handle more complex data and operations as needed.