Subscriptions

# Schema
  type UserStatus {
    userId: String!
    isOnline: Boolean!
  }


  type Subscription {
    userStatusUpdated: UserStatus!
  }

  # Usage
  subscription getUserStatusUpdates {
    userStatusUpdated {
      userId
      isOnline
    }
  }

import { ApolloServer } from '@apollo/server';
  import { startStandaloneServer } from '@apollo/server/standalone'
  import { gql } from 'graphql-tag';


  const products = [
    {
      id: '1',
      name: 'Daikin 1.5T',
      category: 'Air Conditioners',
    },
    {
      id: '2',
      name: 'God Of War',
      category: 'Gaming',
    }
  ];

const typeDefs = gql`
    type Product {
      id: ID!
      name: String
      category: String
    }
    type Query {
      getProductById(id: ID!): Product
      getAllProducts: [Product]
    }
  `;

const resolvers = {
    Query: {
      getAllProducts: () => products,
      getProductById: (parent, args, contextValue, info) => products.find((product) => args.id === product.id)
    },
  };

const server = new ApolloServer({
    typeDefs: schema,
    resolvers,
  });
  startStandaloneServer(server, { listen: { port: 4000 } }).then(({ url }) => {
    console.log(`🚀 Apollo Server listening at: ${url}`);
  });

import { ApolloServer } from '@apollo/server';
  import { startStandaloneServer } from '@apollo/server/standalone'
  import { gql } from 'graphql-tag';
 
  const products = [
    {
      id: '1',
      name: 'Daikin 1.5T',
      category: 'Air Conditioners',
    },
    {
      id: '2',
      name: 'God Of War',
      category: 'Gaming',
    }
  ];
 
  const typeDefs = gql`
    type Product {
      id: ID!
      name: String
      category: String
    }
    type Query {
      getProductById(id: ID!): Product
      getAllProducts: [Product]
    }
  `;


  const resolvers = {
    Query: {
      getAllProducts: () => products,
      getProductById: (parent, args, contextValue, info) => products.find((product) => args.id === product.id)
    },
  };
 
  const server = new ApolloServer({
    typeDefs,
    resolvers,
  });
 
  startStandaloneServer(server, { listen: { port: 4000 } }).then(({ url }) => {
    console.log(`🚀 Apollo Server listening at: ${url}`);
  });

import { ApolloServer } from '@apollo/server';
  import { expressMiddleware } from '@apollo/server/express4';
  import { ApolloServerPluginDrainHttpServer } from '@apollo/server/plugin/drainHttpServer';
  import { createServer } from 'http';
  import { makeExecutableSchema } from '@graphql-tools/schema';
  import { WebSocketServer } from 'ws';
  import { useServer } from 'graphql-ws/lib/use/ws';
  import { PubSub } from 'graphql-subscriptions';
  import { gql } from 'graphql-tag';
  import express from 'express';
  import bodyParser from 'body-parser';
  import cors from 'cors';

  async function startServer() {
    // main implementation goes here
  }

  startServer()

const typeDefs = gql`
    type UserStatus {
      userId: String!
      isOnline: Boolean!
    }


    type Query {
      userStatus: UserStatus!
    }


    type Subscription {
      userStatusUpdated: UserStatus!
    }
  `;

const pubsub = new PubSub();
  const resolvers = {
    Query: {
      userStatus() {
        return userStatus;
      },
    },
    Subscription: {
      userStatusUpdated: {
        subscribe: () => pubsub.asyncIterator(['USER_STATUS_UPDATED']),
      },
    },
  };

const schema = makeExecutableSchema({ typeDefs, resolvers });

const app = express();
  const httpServer = createServer(app);

const wsServer = new WebSocketServer({
    server: httpServer,
    path: '/',
  });
  const serverCleanup = useServer({ schema }, wsServer);

const server = new ApolloServer({
    schema,
    plugins: [
      ApolloServerPluginDrainHttpServer({ httpServer }),
      {
        async serverWillStart() {
          return {
            async drainServer() {
              await serverCleanup.dispose();
            },
          };
        },  
      },
    ],
  });


  await server.start();
  app.use('/', cors(), bodyParser.json(), expressMiddleware(server));

const PORT = 4000;
  httpServer.listen(PORT, () => {
    console.log(`🚀 GraphQL Server ready at http://localhost:${PORT}/`);
    console.log(`🚀 GraphQL WS ready at ws://localhost:${PORT}/`);
  });

let userStatus = {
    userId: "ceqak08y3sjkbasdfausjg",
    isOnline: true
  };
  function toggleUserStatus() {
    userStatus.isOnline = !userStatus.isOnline;
    pubsub.publish('USER_STATUS_UPDATED', { userStatusUpdated: userStatus });
    setTimeout(toggleUserStatus, 5000);
  }
  toggleUserStatus()

import { ApolloServer } from '@apollo/server';
  import { expressMiddleware } from '@apollo/server/express4';
  import { ApolloServerPluginDrainHttpServer } from '@apollo/server/plugin/drainHttpServer';
  import { createServer } from 'http';
  import { makeExecutableSchema } from '@graphql-tools/schema';
  import { WebSocketServer } from 'ws';
  import { useServer } from 'graphql-ws/lib/use/ws';
  import { PubSub } from 'graphql-subscriptions';
  import { gql } from 'graphql-tag';
  import express from 'express';
  import bodyParser from 'body-parser';
  import cors from 'cors';
 
  async function startServer() {
 
    const typeDefs = gql`
      type UserStatus {
        userId: String!
        isOnline: Boolean!
      }
 
      type Query {
        userStatus: UserStatus!
      }
 
      type Subscription {
        userStatusUpdated: UserStatus!
      }
    `;
    const pubsub = new PubSub();
    const resolvers = {
      Query: {
        userStatus() {
          return userStatus;
        },
      },
      Subscription: {
        userStatusUpdated: {
          subscribe: () => pubsub.asyncIterator(['USER_STATUS_UPDATED']),
        },
      },
    };
    const schema = makeExecutableSchema({ typeDefs, resolvers });
 
 
    const app = express();
    const httpServer = createServer(app);
    const wsServer = new WebSocketServer({
      server: httpServer,
      path: '/',
    });
    const serverCleanup = useServer({ schema }, wsServer);
    const server = new ApolloServer({
      schema,
      plugins: [
        ApolloServerPluginDrainHttpServer({ httpServer }),
        {
          async serverWillStart() {
            return {
              async drainServer() {
                await serverCleanup.dispose();
              },
            };
          },
        },
      ],
    });
 
    await server.start();
    app.use('/', cors(), bodyParser.json(), expressMiddleware(server));
 
   
    const PORT = 4000;
    httpServer.listen(PORT, () => {
      console.log(`🚀 GraphQL Server ready at http://localhost:${PORT}/`);
      console.log(`🚀 GraphQL WS ready at ws://localhost:${PORT}/`);
    });
 
   
    let userStatus = {
      userId: "ceqak08y3sjkbasdfausjg",
      isOnline: true
    };
    function toggleUserStatus() {
      userStatus.isOnline = !userStatus.isOnline;
      pubsub.publish('USER_STATUS_UPDATED', { userStatusUpdated: userStatus });
      setTimeout(toggleUserStatus, 5000);
    }
    toggleUserStatus()
  }
 
  startServer()