Suscriptions with GraphQL and Node JS

Learn how to use subscriptions with Node JS in GraphQL

Backend

1) Installation of dependencies

npm i nodemon apollo-server

2) Apollo server creation

import { ApolloServer } from "apollo-server";
const server = new ApolloServer({
  typeDefs,
  resolvers,
});
// The `listen` method launches a web server.
server.listen().then(({ url, subscriptionsUrl }) => {
console.log(`🚀 Server ready at ${url}`);
console.log(`🚀 Subscriptions ready at ${subscriptionsUrl}`);
});

3) Typedefs

const typeDefs = gql`
  type Subscription {
   postAdded: Post
  }
  type Query {
   posts: [Post]
  }
  type Mutation {
   addPost(author: String, comment: String): Post
  }
  type Post {
   author: String
   comment: String
  }
`;

Resolvers and Queries

const typeDefs = gql`
type Subscription {
   postAdded: Post
  }
type Query {
   posts: [Post]
  }
type Mutation {
   addPost(author: String, comment: String): Post
  }
type Post {
   author: String
   comment: String
  }
`;
const posts = [
 {
  author: "Nelson",
  comment: "Hello",
 },
 {
   author: "Steve",
   comment: "Hello GraphQL",
 },
];
const POST_ADDED = "POST_ADDED";
const resolvers = {
 Subscription: {
 postAdded: {
  // Additional event labels can be passed to asyncIterator creation
  subscribe: () => pubsub.asyncIterator([POST_ADDED]),
 },
},
 Query: {
  posts() {
   return posts
 },
},
 Mutation: {
   addPost(_, args) {
    //Execute event
    pubsub.publish(POST_ADDED, { postAdded: args });
    posts.push(args)
    return args
  },
 },
};
const server = new ApolloServer({
  typeDefs,
  resolvers,
});

Finally

const POST_ADDED = "POST_ADDED";
const resolvers = {
 Subscription: {
 postAdded: {
  // Additional event labels can be passed to asyncIterator creation
  subscribe: () => pubsub.asyncIterator([POST_ADDED]),
 },
},
Query: {
  posts() {
   return posts
 },
},
Mutation: {
   addPost(_, args) {
    //Execute event
    pubsub.publish(POST_ADDED, { postAdded: args });
    posts.push(args)
    return args
  },
 },
};
const server = new ApolloServer({
  typeDefs,
  resolvers,
});
// The `listen` method launches a web server.
server.listen().then(({ url, subscriptionsUrl }) => {
console.log(`🚀 Server ready at ${url}`);
console.log(`🚀 Subscriptions ready at ${subscriptionsUrl}`);
});

Repository in Github https://github.com/nelson-Web/nodejs-graphql-suscriptions