firefuncs

Create Firebase cloud functions from functions marked with decorators.

npm i firefuncs

To demonstrate the use of firefuncs, let's create Firebase cloud functions with and without firefuncs.

Creating Firebase cloud functions without firefuncs

For a start you may have all your cloud functions in one file.

index.ts

import * as admin from 'firebase-admin';
import * as functions from 'firebase-functions';

exports.helloWorld = functions.https.onRequest((request, response) => {
 response.send('Hello from Firebase!\n\n');
});

exports.initializeApp = functions.https.onRequest(async (request, response) => {
 admin.initializeApp(functions.config().firebase);
});

Over time that file grows and that necessitates breaking it into smaller files. You may do so as shown below.

hello.functions.ts

import * as admin from 'firebase-admin';
import * as functions from 'firebase-functions';

export const helloWorld = (request, response) => {
 response.send('Hello from Firebase!\n\n');
};

export const initializeApp = async (request, response) => {
 admin.initializeApp(functions.config().firebase);
};

index.ts

// import * as admin from 'firebase-admin';
import * as functions from 'firebase-functions';
import { helloWorld, initializeApp } from './hello.functions';

exports.helloWorld = functions.https.onRequest(helloWorld);

exports.initializeApp = functions.https.onRequest(initializeApp);

While this is a lot better than the first example, it still requires that index.ts be modified every time new functions are added or existing ones removed.

To get a solution where index.ts never needs to change even as functions are added or removed, we need a way of specifying what a function is meant for; we need a way of marking or decorating a function with its purpose. Enter decorators!

Creating Firebase cloud functions using firefuncs

firefuncs makes use of decorators, an experimental TypeScript feature. Ensure you enable experimentalDecorators and emitDecoratorMetadata options in tsconfig.json.

{
  "compilerOptions": {
    /* Other Options */

    /* Experimental Options */
    "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
    "emitDecoratorMetadata": true         /* Enables experimental support for emitting type metadata for decorators. */
  }
}

Install firefuncs

npm i firefuncs

Move your functions into classes and decorate them with the appropriate decorators. In the example below, we want our functions to handle HTTP requests, so we decorate them with the onRequest decorator.

functions/hello.functions.ts

import * as admin from 'firebase-admin';
import * as functions from 'firebase-functions';
import { onRequest } from 'firefuncs';

export class Hello {
    @onRequest()
    public helloWorld(request, response) {
        response.send('Hello from Firebase!\n\n');
    }
    @onRequest()
    public initializeApp(request, response) {
        admin.initializeApp(functions.config().firebase);
    }
}

To create cloud functions, use the getFunctions function from firefuncs, supplying a glob pattern that matches all the files containing JavaScript functions that should be converted to Firebase cloud functions.

index.ts

import { getFunctions } from 'firefuncs';

// search the 'functions' directory and all its subdirectories
// for JavaScript or TypeScript files
const funcs = getFunctions(__dirname + '/functions/**/*.{js,ts}');

// just writing 'exports = funcs;' won't work
// you have to loop through the keys in 'funcs'
// and assign their values to matching keys in 'exports'
Object.keys(funcs).forEach(key => {
    exports[key] = funcs[key];
});

Now you can add more functions in the /functions directory and never need to edit index.ts for the added functions to be discovered and converted to Firebase cloud functions.

Firefuncs decorators

• onRequest

• onFirestoreCreate, onFirestoreDelete, onFirestoreUpdate, onFirestoreWrite

• onDatabaseCreate, onDatabaseDelete, onDatabaseUpdate, onDatabaseWrite

• onSchedule

• onCall

• onAuthUserCreate, onAuthUserDelete