Fix #42: multiple authentication backends (#47)

* Revamp authentication to allow multiple backends

* Make router generate a login route for each backend

* Apply black

* Remove unused imports

* Complete docstrings

* Update documentation

* WIP add cookie auth

* Complete cookie auth unit tests

* Add documentation for cookie auth

* Fix cookie backend default name

* Don't make cookie return a Response

fastapi_users/authentication/cookie.py

@@ -0,0 +1,53 @@
+from typing import Any, Optional
+
+from fastapi.security import APIKeyCookie
+from starlette.requests import Request
+from starlette.responses import Response
+
+from fastapi_users.authentication.jwt import JWTAuthentication
+from fastapi_users.models import BaseUserDB
+
+
+class CookieAuthentication(JWTAuthentication):
+    """
+    Authentication backend using a cookie.
+
+    Internally, uses a JWT token to store the data.
+
+    :param secret: Secret used to encode the cookie.
+    :param lifetime_seconds: Lifetime duration of the cookie in seconds.
+    :param cookie_name: Name of the cookie.
+    :param name: Name of the backend. It will be used to name the login route.
+    """
+
+    lifetime_seconds: int
+    cookie_name: str
+
+    def __init__(
+        self,
+        secret: str,
+        lifetime_seconds: int,
+        cookie_name: str = "fastapiusersauth",
+        name: str = "cookie",
+    ):
+        super().__init__(secret, lifetime_seconds, name=name)
+        self.lifetime_seconds = lifetime_seconds
+        self.cookie_name = cookie_name
+        self.api_key_cookie = APIKeyCookie(name=self.cookie_name, auto_error=False)
+
+    async def get_login_response(self, user: BaseUserDB, response: Response) -> Any:
+        token = await self._generate_token(user)
+        response.set_cookie(
+            self.cookie_name,
+            token,
+            max_age=self.lifetime_seconds,
+            secure=True,
+            httponly=True,
+        )
+
+        # We shouldn't return directly the response
+        # so that FastAPI can terminate it properly
+        return None
+
+    async def _retrieve_token(self, request: Request) -> Optional[str]:
+        return await self.api_key_cookie.__call__(request)