callable-functions

Firebase HTTPS Callable functions Quickstart (Python)

This quickstart shows how to write callable functions with the Firebase SDK for Cloud Functions in Python. Callable functions are HTTPS functions that your app calls with a Firebase client SDK, which handles the request format and passes along the user's authentication state.

Read more about callable functions

Functions code

See functions/main.py for the code. It defines two functions:

• addnumbers: Adds two numbers, firstNumber and secondNumber, passed in the request data and returns the result. It raises an HttpsError with the INVALID_ARGUMENT code if either number is missing.
• addmessage: Saves a message to the Realtime Database after removing swear words. The function requires the caller to be signed in and records the caller's user ID, name, picture, and email with the message.

Deploy

1. Create a Firebase project in the Firebase console and enable the Realtime Database.

2. Install the Firebase CLI and sign in with firebase login.

3. Clone this repo and open the Python/quickstarts/callable-functions directory.

4. Select your project with firebase use --add.

5. Create a virtual environment and install the dependencies:

   cd functions
   python3 -m venv venv
   source venv/bin/activate
   pip install -r requirements.txt
   cd ..

6. Deploy with firebase deploy --only functions.

Test

Callable functions use a specific request format: a POST request with a JSON body whose payload sits under a data key, plus a few headers the client SDKs set for you. The Testing tab in the Google Cloud console doesn't follow that format, so calls from there fail. Use one of the following instead.

Call the function from a client

Call the function from your app with a Firebase client SDK, for example with the Web SDK:

import { getFunctions, httpsCallable } from "firebase/functions";

const addNumbers = httpsCallable(getFunctions(), "addnumbers");
const result = await addNumbers({ firstNumber: 1, secondNumber: 2 });
console.log(result.data.operationResult); // 3

The addmessage function requires a signed-in user, so sign in with Firebase Authentication before you call it. The SDK attaches the user's ID token to the request.

Call the function with curl

For a quick check of addnumbers, which doesn't require authentication, send the callable request format yourself. Run the function in the Local Emulator Suite:

firebase emulators:start --only functions

Then call it:

curl -X POST http://127.0.0.1:5001/YOUR_PROJECT_ID/us-central1/addnumbers \
  -H "Content-Type: application/json" \
  -d '{"data": {"firstNumber": 1, "secondNumber": 2}}'

The response wraps the function's return value in a result key:

{"result": {"firstNumber": 1, "secondNumber": 2, "operator": "+", "operationResult": 3}}

The same request works against the deployed function at its https:// URL, which firebase deploy prints.

License

© Google, 2023. Licensed under an Apache-2 license.