Update AuthenticationBackend signature

docs/authentication.md

@@ -13,8 +13,6 @@ The class `AuthenticationBackend` has three methods you need to override:
 * `logout`: Will be called only for the logout, usually clearin the session.
 
 ```python
-from typing import Optional
-
 from sqladmin import Admin
 from sqladmin.authentication import AuthenticationBackend
 from starlette.requests import Request
@@ -37,13 +35,14 @@ class AdminAuth(AuthenticationBackend):
         request.session.clear()
         return True
 
-    async def authenticate(self, request: Request) -> Optional[RedirectResponse]:
+    async def authenticate(self, request: Request) -> bool:
         token = request.session.get("token")
 
         if not token:
-            return RedirectResponse(request.url_for("admin:login"), status_code=302)
+            return False
 
         # Check the token in depth
+        return True
 
 
 authentication_backend = AdminAuth(secret_key="...")
@@ -56,8 +55,6 @@ admin = Admin(app=..., authentication_backend=authentication_backend، ...)
 ??? example "Full Example"
 
     ```python
-    from typing import Optional
-
     from sqladmin import Admin, ModelView
     from sqladmin.authentication import AuthenticationBackend
     from sqlalchemy import Column, Integer, String, create_engine
@@ -93,9 +90,14 @@ admin = Admin(app=..., authentication_backend=authentication_backend، ...)
             request.session.clear()
             return True
 
-        async def authenticate(self, request: Request) -> Optional[RedirectResponse]:
-            if not "token" in request.session:
-                return RedirectResponse(request.url_for("admin:login"), status_code=302)
+        async def authenticate(self, request: Request) -> bool:
+            token = request.session.get("token")
+
+            if not token:
+                return False
+
+            # Check the token in depth
+            return True
 
 
     app = Starlette()
@@ -120,7 +122,7 @@ You can also integrate OAuth into SQLAdmin, for this example we will integrate G
 If you have followed the previous example, there are only two changes required to the authentication flow:
 
 ```python
-from typing import Optional
+from typing import Union
 
 from authlib.integrations.starlette_client import OAuth
 from sqladmin.authentication import AuthenticationBackend
@@ -155,12 +157,14 @@ class AdminAuth(AuthenticationBackend):
         request.session.clear()
         return True
 
-    async def authenticate(self, request: Request) -> Optional[RedirectResponse]:
+    async def authenticate(self, request: Request) -> Union[bool, RedirectResponse]:
         user = request.session.get("user")
         if not user:
             redirect_uri = request.url_for('login_google')
             return await google.authorize_redirect(request, redirect_uri)
 
+        return True
+
 
 admin = Admin(app=app, engine=engine, authentication_backend=AdminAuth("test"))
 

sqladmin/authentication.py

@@ -1,11 +1,11 @@
 import functools
 import inspect
-from typing import Any, Callable, Optional
+from typing import Any, Callable, Union
 
 from starlette.middleware import Middleware
 from starlette.middleware.sessions import SessionMiddleware
 from starlette.requests import Request
-from starlette.responses import Response
+from starlette.responses import RedirectResponse, Response
 
 
 class AuthenticationBackend:
@@ -32,14 +32,14 @@ async def logout(self, request: Request) -> bool:
         """
         raise NotImplementedError()
 
-    async def authenticate(self, request: Request) -> Optional[Response]:
+    async def authenticate(self, request: Request) -> Union[Response, bool]:
         """Implement authenticate logic here.
         This method will be called for each incoming request
         to validate the authentication.
 
-        If the request is authenticated, this method should return `None` or do nothing.
-        Otherwise it should return a `Response` object,
-        like a redirect to the login page or SSO page.
+        If a 'Response' or `RedirectResponse` is returned,
+        that response is returned to the user,
+        otherwise a True/False is expected.
         """
         raise NotImplementedError()
 
@@ -56,8 +56,10 @@ async def wrapper_decorator(*args: Any, **kwargs: Any) -> Any:
         auth_backend = getattr(admin, "authentication_backend", None)
         if auth_backend is not None:
             response = await auth_backend.authenticate(request)
-            if response and isinstance(response, Response):
+            if isinstance(response, Response):
                 return response
+            if not bool(response):
+                return RedirectResponse(request.url_for("admin:login"), status_code=302)
 
         if inspect.iscoroutinefunction(func):
             return await func(*args, **kwargs)

tests/test_authentication.py

@@ -24,9 +24,10 @@ async def logout(self, request: Request) -> bool:
         request.session.clear()
         return True
 
-    async def authenticate(self, request: Request) -> RedirectResponse:
-        if "token" not in request.session:
+    async def authenticate(self, request: Request) -> bool:
+        if "token" in request.session:
             return RedirectResponse(request.url_for("admin:login"), status_code=302)
+        return False
 
 
 app = Starlette()