dart_firebase_functions

⚠️ Please note that this project is still in its early stages, so it may contain bugs and undergo frequent breaking changes.

Motivation

This project aims to provide functionality similar to the Node.js firebase-functions package in Dart, using the functions_framework and dart_firebase_admin packages.

How to use

Install

Please add the following to your Flutter app's pubspec.yaml:

dependencies:
  dart_firebase_admin: latest
  dart_firebase_functions: latest
  functions_framework: latest
  shelf:

dev_dependencies:
  build_runner:
  dart_firebase_functions_builder: latest

Define adminApp

Before defining functions, it required to configure FirebaseAdminApp with your credentials.

import 'package:dart_firebase_admin/dart_firebase_admin.dart';
import 'package:dart_firebase_functions/dart_firebase_functions.dart';
import 'package:functions_framework/functions_framework.dart';

final adminApp = FirebaseAdminApp.initializeApp(
  'your-project-id',
  Credential.fromServiceAccountParams(
    clientId: 'your-client-id',
    privateKey: 'your-private-key',
    email: 'your-client-email',
  ),
);

final firestore = Firestore(adminApp);

final auth = Auth(adminApp);

final messaging = Messaging(adminApp);

Define HTTP function

Use @HTTPFunction() to define HTTP Function.

import 'package:dart_firebase_admin/dart_firebase_admin.dart';
import 'package:dart_firebase_functions/dart_firebase_functions.dart';
import 'package:shelf/shelf.dart';

FirebaseAdminApp initializeAdminApp() => adminApp;

@HTTPFunction()
Future<Response> hello(Request request) async => Response.ok('Hello, World!');

Then, run builder_runner to generate codes.

dart pub run build_runner build -d

You will get the code like the following:

// GENERATED CODE - DO NOT MODIFY BY HAND

import 'package:dart_firebase_functions/dart_firebase_functions.dart';
import 'package:functions_framework/serve.dart';
import 'package:server/functions.dart' as function_library;

Future<void> main(List<String> args) async {
  final app = function_library.initializeAdminApp();
  FirebaseFunctions.initialize(app);
  await serve(args, _nameToFunctionTarget);
}

FunctionTarget? _nameToFunctionTarget(String name) => switch (name) {
      'hello' => FunctionTarget.http(
          function_library.hello,
        ),
      _ => null
    };

Define Cloud Firestore triggered function

In order to define Cloud Firestore document creation triggered function, use @OnDocumentCreated with the parameters like the following example.

import 'package:dart_firebase_admin/dart_firebase_admin.dart';
import 'package:dart_firebase_functions/dart_firebase_functions.dart';
import 'package:functions_framework/functions_framework.dart';

FirebaseAdminApp initializeAdminApp() => adminApp;

@OnDocumentCreated('todos/{todoId}')
Future<void> oncreatetodo(
  ({String todoId}) params,
  QueryDocumentSnapshot snapshot,
  RequestContext context,
) async {
  context.logger.debug('todoId: ${params.todoId}');
  final data = snapshot.data();
  final title = data?['title'] as String?;
  await snapshot.ref.update({'title': '$title from server!'});
}

It is also possible to be triggered by nested document creation.

@OnDocumentCreated('todos/{todoId}/logs/{logId}')
Future<void> oncreatelog(
  ({String todoId, String logId}) params,
  QueryDocumentSnapshot snapshot,
  RequestContext context,
) async {
  final todoId = params.todoId;
  final logId = params.logId;
  final data = snapshot.data();
  context.logger.debug('todoId: $todoId');
  context.logger.debug('logId: $logId');
  context.logger.debug('data: $data');
}

Then, run builder_runner to generate codes.

dart pub run build_runner build -d

You will get the code like the following:

// GENERATED CODE - DO NOT MODIFY BY HAND

import 'package:dart_firebase_functions/dart_firebase_functions.dart';
import 'package:functions_framework/serve.dart';
import 'package:server/functions.dart' as function_library;

Future<void> main(List<String> args) async {
  final app = function_library.initializeAdminApp();
  FirebaseFunctions.initialize(app);
  await serve(args, _nameToFunctionTarget);
}

FunctionTarget? _nameToFunctionTarget(String name) => switch (name) {
      'oncreatetodo' => FunctionTarget.cloudEventWithContext((event, context) {
          const pathPattern = 'todos/{todoId}';
          final documentIds =
              FirestorePathParser(pathPattern).parse(event.subject!);
          final data = QueryDocumentSnapshotBuilder(event).fromCloudEvent();
          return function_library.oncreatetodo(
            (todoId: documentIds['todoId']!),
            data.snapshot,
            context,
          );
        }),
      'oncreatelog' => FunctionTarget.cloudEventWithContext((event, context) {
          const pathPattern = 'todos/{todoId}/logs/{logId}';
          final documentIds =
              FirestorePathParser(pathPattern).parse(event.subject!);
          final data = QueryDocumentSnapshotBuilder(event).fromCloudEvent();
          return function_library.oncreatelog(
            (todoId: documentIds['todoId']!, logId: documentIds['logId']!),
            data.snapshot,
            context,
          );
        }),
      _ => null
    };