Router Group Error

[SAB13711]

Currently there is an error when you attempt to create a router group.
The error:

2026-05-26T16:12:56.817Z [ERROR  ] Failed to load C:\coding_projects\work\hertex\giftcard-service\src\routes\giftcard_routes.py: <lambda>() takes 0 positional arguments but 1 was given

The code that caused it:

from tina4_python.core.router import Router, get, post, put, delete

from src.app.services import giftcard_service

Router.group("/api/v1/giftcards", lambda: [
    Router.get("/user/{email}", giftcards_for_user),
    Router.get("/{giftcard_number}/balance", specific_giftcard_balance),
    Router.post("/create", create_giftcard),
    Router.put("/{giftcard_number}/update-image", update_giftcard_image),
    Router.post("/{giftcard_number}/redeem", redeem_giftcard),
    Router.post("/{giftcard_number}/top-up", top_up_giftcard),
])

async def giftcards_for_user(email: str, request, response):
    request_response = giftcard_service.get_giftcards_for_user(email)
    return response.json(request_response, request_response["code"])

async def specific_giftcard_balance(giftcard_number: str, request, response):
    request_response = giftcard_service.get_giftcard_balance(giftcard_number)
    return response.json(request_response, request_response["code"])

async def create_giftcard(request, response):
    email = request.body.get("email")
    request_response = giftcard_service.create_new_giftcard(email)
    return response.json(request_response, request_response["code"])

async def update_giftcard_image(request, response):
    giftcard_number = request.body.get("giftcard_number")
    image_name = request.body.get("image_name")
    request_response = giftcard_service.update_giftcard_image(giftcard_number, image_name)
    return response.json(request_response, request_response["code"])

async def redeem_giftcard(giftcard_number: str, request, response):
    user_email = request.body.get("user_email")
    amount = request.body.get("amount")
    request_response = giftcard_service.process_giftcard_transaction(giftcard_number, user_email, False, amount)
    return response.json(request_response, request_response["code"])

async def top_up_giftcard(giftcard_number: str, request, response):
    user_email = request.body.get("user_email")
    amount = request.body.get("amount")
    payment_id = request.body.get("payment_id")
    request_response = giftcard_service.process_giftcard_transaction(giftcard_number, user_email, False, amount, payment_id)
    return response.json(request_response, request_response["code"])

[andrevanzuydam]

The source contract is intentional — Router.group() passes a RouteGroup instance to the callback so the prefix and middleware propagate to nested groups. The chapter 2 §5 docs were wrong — they showed a zero-arg lambda: [...] which is unsupported and crashes with the TypeError you saw.

Updated the docs to the correct form on both sites:

from tina4_python.core.router import Router

Router.group("/api/v1/giftcards", lambda group: [
    group.get("/user/{email}", giftcards_for_user),
    group.get("/{giftcard_number}/balance", specific_giftcard_balance),
    group.post("/create", create_giftcard),
    group.put("/{giftcard_number}/update-image", update_giftcard_image),
    group.post("/{giftcard_number}/redeem", redeem_giftcard),
    group.post("/{giftcard_number}/top-up", top_up_giftcard),
])

The lambda must accept the group argument, and you should call group.get/post/put/... on it (not top-level Router.get/...) so the /api/v1/giftcards prefix propagates.

Doc commits: tina4stack/tina4-documentation@7903836, tina4stack/tina4-book@480e8af. Live at https://tina4.com/python/02-routing.html#_5-route-groups after the next deploy.