utpd-oauth-client

Client library for the utpd-oauth service, with framework integrations for FastAPI and NiceGUI.

Installation

uv add utpd-oauth-client

The only dependency is httpx. Framework integrations assume you already have the relevant framework installed.

Usage

Core Client (Framework-Agnostic)

The core client works anywhere - scripts, CLI tools, any web framework:

from utpd_oauth_client import OAuthClient

client = OAuthClient("https://utpd-oauth.ward.au")

# Step 1: Get the URL to redirect users to
login_url = client.login_url("https://myapp.com/auth/callback")
# -> "https://utpd-oauth.ward.au/login?next_url=https%3A%2F%2Fmyapp.com%2Fauth%2Fcallback"

# Step 2: After OAuth completes, exchange the token_code for an access_token
access_token = await client.exchange(token_code)

FastAPI Integration

The FastAPI integration provides a router factory that handles the OAuth redirect flow:

from fastapi import FastAPI, Request
from fastapi.responses import RedirectResponse
from starlette.responses import Response

from utpd_oauth_client import OAuthClient
from utpd_oauth_client.fastapi import create_auth_router

app = FastAPI()
client = OAuthClient(settings.oauth_service_url)


async def handle_token(token: str, request: Request) -> Response:
    """Called after successful OAuth with the access_token."""
    # Store token, create session, look up user, etc.
    request.session["access_token"] = token
    return RedirectResponse("/")


router = create_auth_router(
    client=client,
    public_base_url=settings.public_base_url,  # e.g. "https://myapp.com"
    on_token=handle_token,
)
app.include_router(router)

This creates two endpoints:

• GET /auth/start - Redirects user to utpd-oauth to begin the flow
• GET /auth/callback - Receives the token_code, exchanges it, calls your handler

NiceGUI Integration

The NiceGUI integration adds OAuth routes to your NiceGUI app:

import os

from nicegui import app, ui
from starlette.requests import Request
from starlette.responses import RedirectResponse, Response

from utpd_oauth_client import OAuthClient
from utpd_oauth_client.nicegui import setup_oauth_routes

client = OAuthClient(os.getenv("OAUTH_SERVICE_URL"))


async def handle_token(token: str, request: Request) -> Response:
    """Called after successful OAuth with the access_token."""
    app.storage.user["access_token"] = token
    app.storage.user["authenticated"] = True
    return RedirectResponse("/")


setup_oauth_routes(
    app=app,
    client=client,
    public_base_url=os.getenv("PUBLIC_BASE_URL"),
    on_token=handle_token,
)


@ui.page("/")
def main_page() -> None:
    if not app.storage.user.get("authenticated"):
        ui.link("Login with Untappd", "/auth/start")
    else:
        ui.label(f"Welcome! Your token: {app.storage.user.get('access_token', '')[:10]}...")

Configuration

Both integrations accept these parameters:

Error Handling

The client raises TokenExchangeError when the exchange fails:

from utpd_oauth_client import OAuthClient, TokenExchangeError

client = OAuthClient("https://utpd-oauth.ward.au")

try:
    token = await client.exchange(token_code)
except TokenExchangeError as e:
    print(f"Exchange failed: {e}")
    print(f"Status code: {e.status_code}")
    print(f"Detail: {e.detail}")

For framework integrations, you can provide a custom error handler:

async def handle_error(exc: TokenExchangeError, request: Request) -> Response:
    # Log the error, show a friendly message, etc.
    return RedirectResponse("/login?error=oauth_failed")


router = create_auth_router(
    client=client,
    public_base_url=settings.public_base_url,
    on_token=handle_token,
    error_handler=handle_error,
)

Development

cd utpd-oauth-client
uv sync --all-groups
uv run pytest

Sequence Diagram

sequenceDiagram
    participant User
    participant YourApp
    participant utpd-oauth-client
    participant utpd-oauth
    participant Untappd

    User->>YourApp: GET /auth/start
    YourApp->>utpd-oauth-client: client.login_url(callback_url)
    utpd-oauth-client-->>YourApp: redirect URL
    YourApp->>utpd-oauth: Redirect to /login
    utpd-oauth->>Untappd: Redirect to OAuth
    Untappd->>utpd-oauth: Callback with code
    utpd-oauth->>YourApp: Redirect to /auth/callback?token_code=...
    YourApp->>utpd-oauth-client: client.exchange(token_code)
    utpd-oauth-client->>utpd-oauth: POST /get-token
    utpd-oauth-->>utpd-oauth-client: { access_token }
    utpd-oauth-client-->>YourApp: access_token
    YourApp->>YourApp: on_token(access_token, request)
    YourApp-->>User: Redirect to app