Firefuncs NPM | npm.io

firefuncs

Create Firebase cloud functions from Typescript 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 onHttpsRequest decorator.

functions/hello.functions.ts

import * as admin from 'firebase-admin';
import * as functions from 'firebase-functions';
import { func, onHttpsRequest } from 'firefuncs';

export class Hello {
    @func()
    @onHttpsRequest()
    public helloWorld(request, response) {
        response.send('Hello from Firebase!\n\n');
    }

    @func()
    @onHttpsRequest()
    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 TypeScript class methods 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}');

// 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

Multiple decorators

Decorators that start with on (like onFirestoreCreate, onStorageObjectArchive) are primary decorators. They are the ones that ultimately determine what type of cloud function is created from a decorated TypeScript class method.

You can apply multiple primary decorators on a single class method. You can even repeat a primary decorator multiple times on a single class method. This has the effect of creating multiple cloud functions from a single class method, one cloud function for each primary decorator.

Autogenerated cloud function names

Specifying name in func

You can specify a name for the produced cloud function by supplying a name argument to the @func decorator.

import { func, onHttpsRequest } from 'firefuncs';

export class Hello {
    @func('my_cloud_function')
    @onHttpsRequest()
    public helloWorld(request, response) {
        response.send('Hello from Firebase!\n\n');
    }
}

The produced cloud function will be named my_cloud_function.

Specifying no name in func

If you supply no name argument to the @func decorator, the produced cloud function will be named using the name of the TypeScript class and the name of the method, concatenated using an underscore (_).

import { func, onHttpsRequest } from 'firefuncs';

export class Hello {
    @func()
    @onHttpsRequest()
    public helloWorld(request, response) {
        response.send('Hello from Firebase!\n\n');
    }
}

The produced cloud function will be named Hello_helloWorld.

Applying multiple primary decorators on a method

If multiple primary decorators are applied to a method, the produced cloud functions will be named as described above, followed by a number (ranging from 1 to n, where n is the number of primary decorators applied to the method), followed by an underscore (_), and followed by the name of the decorator.

Example 1

import { func, onStorageObjectArchive, onStorageObjectDelete, onStorageObjectFinalize } from 'firefuncs';

export class Hello {
    @func('my_cloud_function')
    @onStorageObjectArchive()
    @onStorageObjectArchive()
    @onStorageObjectDelete()
    @onStorageObjectFinalize()
    public helloWorld(object) {
        response.send('Hello from Firebase!\n\n');
    }
}

This will produce 4 cloud functions named

my_cloud_function1_onStorageObjectFinalize
my_cloud_function2_onStorageObjectDelete
my_cloud_function3_onStorageObjectArchive
my_cloud_function4_onStorageObjectArchive

Example 2

import { func, onStorageObjectArchive, onStorageObjectDelete, onStorageObjectFinalize } from 'firefuncs';

export class Hello {
    @func()
    @onStorageObjectArchive()
    @onStorageObjectArchive()
    @onStorageObjectDelete()
    @onStorageObjectFinalize()
    public helloWorld(object) {
        response.send('Hello from Firebase!\n\n');
    }
}

This will produce 4 cloud functions named