Setup GraphQL And Firebase Functions API

To create a GraphQL Node.js and Firebase functions API with TypeScript and Yarn to post and get blog posts for users, follow these steps:

Install the necessary dependencies using Yarn. This includes the GraphQL and Firebase dependencies, as well as TypeScript and any other necessary libraries:

yarn add graphql apollo-server-express firebase-admin @types/graphql @types/firebase-admin

Create a new file called server.ts and import the necessary libraries:

import { ApolloServer } from 'apollo-server-express';
import { FirebaseAdmin, Firestore } from 'firebase-admin';
import { buildFederatedSchema } from '@apollo/federation';

Initialize the Firebase app and connect to the Firestore database:

const firebaseApp = FirebaseAdmin.initializeApp({
  credential: FirebaseAdmin.credential.cert(serviceAccount),
  databaseURL: "https://<DATABASE_NAME>.firebaseio.com"
});
const firestore = firebaseApp.firestore();

Define the GraphQL schema for the blog post type, including fields for the title, content, and author:

const typeDefs = gql`
  type BlogPost {
    id: ID!
    title: String!
    content: String!
    author: String!
  }

  type Query {
    blogPosts: [BlogPost]
  }

  type Mutation {
    createBlogPost(title: String!, content: String!, author: String!): BlogPost
  }
`;

Implement the resolvers for the GraphQL queries and mutations. These will be used to fetch and store data in the Firestore database:

const resolvers = {
  Query: {
    blogPosts: async () => {
      const blogPostSnapshot = await firestore.collection('blog_posts').get();
      return blogPostSnapshot.docs.map((doc) => doc.data());
    }
  },
  Mutation: {
    createBlogPost: async (parent, args) => {
      const { title, content, author } = args;
      const blogPost = {
        title,
        content,
        author
      };
      const blogPostRef = await firestore.collection('blog_posts').add(blogPost);
      return {
        ...blogPost,
        id: blogPostRef.id
      };
    }
  }
};

Create the Apollo server and pass in the schema and resolvers. Also, enable the GraphQL Playground for testing:

const server = new ApolloServer({
  schema: buildFederatedSchema([{ typeDefs, resolvers }]),
  playground: true
});

Create the Firebase function that will handle requests to the GraphQL API. This function will be triggered when a user makes a request to the API endpoint:

exports.graphql = functions.https.onRequest(server);

Test the API using the GraphQL Playground. You should be able to create and fetch blog posts using the provided queries and mutations.
With these steps, we have created a minimal GraphQL API with firebase functions and Nodejs. Next we will add more functionalities to the API

Watch out for the next Article in the series.