This is backend for It's Urgent Flutter Project. It uses Typescript on Firebase Cloud Functions.

Main backend code can be found in functions/src directory

To avoid writing all functions in one single file index.ts, I am using a feature first project structure which is as follows (NOTE: This is not necessary):

/src
├───core/
├───feature1/
│   ├───reactive/
│   └───restful/
├───feature2/
│   ├───reactive/
│   └───restful/
└───feature3/...

• src/index.ts only contains all the imports from subdirectories like:

  import {helloWorld} from "./hello-world/restful/helloWorld";
  import {createUserRef} from "./auth/reactive/createUserRef";
  import {deleteUserRef} from "./auth/reactive/deleteUserRef";
  
  // this code is required to deploy the imported cloud functions
  export { helloWorld, createUserRef, deleteUserRef};

• src/core/ - Contains all the core functionality which can be common like:

  // filepath: src/core/admin.ts
  
  import * as admin from "firebase-admin";
  
  if (!admin.apps.length) {
  admin.initializeApp();
  }
  
  export default admin;

• Each src/feature/ subfolder contains two subfolders -> reactive/ & restful/.

  • reactive/ - Contains all the cloud functions which are triggered (reactive) in response to firebase products events.

  • Here are a few examples of things that you can do with Cloud Functions triggers:

    • Authentication trigger to send a welcome email when a new user signs in.
    • Receive an email or a Slack notification when a new issue is discovered in Crashlytics.
    • Generate a thumbnail when a user uploads an image to Firebase Storage.
    • Moderate or remove any offensive words that are entered by a user inside your app.
    • Send a FCM notification to users in your app (useful for chat applications).
    • Index your Firestore DB and implement full-text search by tapping into external services like Algolia.

    // filepath: src/auth/reactive/createUserRef.ts
    
    import * as logger from "firebase-functions/logger";
    import * as functionsV1 from "firebase-functions/v1";
    import admin from "../../core/admin";
    
    
    // Create a new userRef in Firestore when a new user is created in Firebase Auth
    export const createUserRef = functionsV1.auth.user().onCreate((user) => {
        const phoneNumber = user.phoneNumber?.replace(/\s+/g, ""); //remove spaces from phone number
        const userRef = admin.firestore().doc(`usersRef/${phoneNumber}`);
    
        logger.info(`New userRef created: ${phoneNumber}`);
        return userRef.set({
            uid: user.uid,
        });
    });

  • restful/ - Contains all the cloud functions which are callable from client like http resful apis.

    // filepath: 'src/hello-world/restful/helloWorld.ts'
    
    import {onRequest} from "firebase-functions/v2/https";
    import * as logger from "firebase-functions/logger";
    
    
    export const helloWorld = onRequest((request, response) => {
        response.send("Hello World!");
    });

    • When someone calls this api endpoint like http://<localhost_or_hosted_url>/<your_firebase project_id>/us-central1/helloWorld

      output response:

      Hello World!
      

• See a full list of supported triggers at https://firebase.google.com/docs/functions
• Start writing functions from https://firebase.google.com/docs/functions/typescript
• File Structure Guide for Complex backend on cloud functions: Serverless computing YouTube Video
• Learn how to setup your first project using Cloud Functions for Firebase. Includes additional resources about Node.js and the Firebase CLI at https://codewithandrea.com/articles/firebase-cloud-functions/