cadwyn

import datetime from fastapi import FastAPI from pydantic import BaseModel, Field from cadwyn import Cadwyn, VersionBundle, VersionedAPIRouter from cadwyn.structure import VersionChange, schema # 1. Define your schemas in the 'latest' version class UserCreateRequest(BaseModel): name: str email: str class UserResource(BaseModel): id: int name: str email: str # 2. Define your API versions # Use ISO date strings for versions for future compatibility (v6.x+) VERSION_2024_01_01 = datetime.date(2024, 1, 1) VERSION_2023_01_01 = datetime.date(2023, 1, 1) # 3. Define version changes class ChangeEmailFieldToOptional(VersionChange): description = 'Make email field optional in UserCreateRequest' version = VERSION_2023_01_01 @schema(UserCreateRequest).alter def alter_user_create_request(cls): cls.email = Field(default=None, union_of=[cls.email, type(None)]) # 4. Create a VersionBundle version_bundle = VersionBundle( latest_version=VERSION_2024_01_01, old_versions=[VERSION_2023_01_01], version_changes=[ChangeEmailFieldToOptional], ) # 5. Initialize Cadwyn and the versioned router app = FastAPI() cadwyn_app = Cadwyn( versions=version_bundle, api_version_header_name='x-api-version', latest_schemas_package=__name__, old_versions_package=__name__ ) # Use a standard FastAPI router but include it via Cadwyn router = VersionedAPIRouter(version_bundle=version_bundle) @router.post('/users', response_model=UserResource) async def create_user(user: UserCreateRequest): # Business logic always works with the latest schema return {"id": 1, "name": user.name, "email": user.email} @router.get('/users/{user_id}', response_model=UserResource) async def get_user(user_id: int): return {"id": user_id, "name": "John Doe", "email": "john.doe@example.com"} # Cadwyn generates and includes versioned routes cadwyn_app.generate_and_include_versioned_routers(app, router) # To run: uvicorn your_module_name:app --reload # Test with curl -H 'x-api-version: 2024-01-01' -X POST -H 'Content-Type: application/json' -d '{"name": "Alice", "email": "alice@example.com"}' http://localhost:8000/users # Test with curl -H 'x-api-version: 2023-01-01' -X POST -H 'Content-Type: application/json' -d '{"name": "Bob"}' http://localhost:8000/users