Firebase Cloud Functions Skill

This skill defines how to correctly call Firebase Cloud Functions from Flutter applications.

When to Use

Use this skill when:

• Implementing callable Cloud Functions in a Flutter project.
• Passing structured data to server-side functions and processing results.
• Handling errors, timeouts, and retries for function calls.
• Configuring region-specific function deployments.
• Testing Cloud Functions locally with the Firebase Emulator Suite.

---

1. Setup and Configuration

flutter pub add cloud_functions

import 'package:cloud_functions/cloud_functions.dart';

// After Firebase.initializeApp():
final functions = FirebaseFunctions.instance;

• Initialize Firebase before using any Cloud Functions features.
• For region-specific deployments, specify the region:

final functions = FirebaseFunctions.instanceFor(region: 'europe-west1');

• Deploy callable functions to Firebase before attempting to call them from the Flutter app.
• Consider implementing App Check to prevent abuse of Cloud Functions.

---

2. Calling Functions

Use httpsCallable to reference a function, then call to invoke it:

final result = await FirebaseFunctions.instance
  .httpsCallable('functionName')
  .call(data);

• Pass data as a Map, it is automatically serialized to JSON:

final result = await FirebaseFunctions.instance
  .httpsCallable('addMessage')
  .call({
    "text": messageText,
    "push": true,
  });

• Access the result via the data property, it is automatically deserialized from JSON:

final responseData = result.data;
// Cast to expected type if needed:
final message = result.data as Map<String, dynamic>;
final status = message['status'] as String;

• Do not pass authentication tokens in function parameters, they are automatically included by the SDK.
• Keep function names consistent between client code and server-side implementations.

---