Provide more extensibility for header-routing defaults

CHANGELOG.md

@@ -5,6 +5,12 @@ Please follow [the Keep a Changelog standard](https://keepachangelog.com/en/1.0.
 
 ## [Unreleased]
 
+## [3.11.0]
+
+### Changed
+
+* Header router is no longer reliant on the API version header -- now it simply takes the API version from the `VersionBundle.api_version_var`, thus making it easy for someone to extend header routing and set their own rules for how the default version is chosen
+
 ## [3.10.1]
 
 ### Fixed

cadwyn/applications.py

@@ -127,6 +127,7 @@ def __init__(
             deprecated=deprecated,
             responses=responses,
             api_version_header_name=api_version_header_name,
+            api_version_var=self.versions.api_version_var,
             lifespan=lifespan,
         )
         self.docs_url = docs_url

cadwyn/routing.py

@@ -1,6 +1,7 @@
 import bisect
 from collections import OrderedDict
 from collections.abc import Sequence
+from contextvars import ContextVar
 from datetime import date
 from functools import cached_property
 from logging import getLogger
@@ -35,11 +36,18 @@ class _RootHeaderAPIRouter(APIRouter):
     matched to the higher versioned route
     """
 
-    def __init__(self, *args: Any, api_version_header_name: str, **kwargs: Any):
+    def __init__(
+        self,
+        *args: Any,
+        api_version_header_name: str,
+        api_version_var: ContextVar[date] | ContextVar[date | None],
+        **kwargs: Any,
+    ):
         super().__init__(*args, **kwargs)
         self.versioned_routes: dict[date, list[BaseRoute]] = {}
         self.unversioned_routes: list[BaseRoute] = []
         self.api_version_header_name = api_version_header_name.lower()
+        self.api_version_var = api_version_var
 
     @cached_property
     def sorted_versioned_routes(self):
@@ -90,10 +98,7 @@ async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
             await self.lifespan(scope, receive, send)
             return
 
-        request_headers = dict(scope["headers"])
-        header_value = request_headers.get(self.api_version_header_name.encode(), b"").decode()
-        if header_value:
-            header_value = date.fromisoformat(header_value)
+        header_value = self.api_version_var.get(None)
 
         # if header_value is None, then it's an unversioned request and we need to use the unversioned routes
         # if there will be a value, we search for the most suitable version

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "cadwyn"
-version = "3.10.1"
+version = "3.11.0"
 description = "Production-ready community-driven modern Stripe-like API versioning in FastAPI"
 authors = ["Stanislav Zmiev <zmievsa@gmail.com>"]
 license = "MIT"