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Version: 0.3.1

AuthRouterComponent

AuthRouterComponent is SimpleRouterComponent plus a session-based access check. Routes marked login_required redirect unauthenticated visitors to the login route.

It uses flask.session for the auth state. Your login flow sets a key in the session, the router reads it before rendering each protected route.

The basic setup​

from dash import html
from dash_extensions.enrich import Output, Trigger
from flask import session
from weaverlet import (
    WeaverletComponent, WeaverletApp, Identifier,
    AuthRouterComponent, RedirectComponent,
)


class LoginPage(WeaverletComponent):
    login_btn = Identifier()

    def __init__(self):
        super().__init__()
        self.redirect = RedirectComponent()

    def get_layout(self, protected_route):
        self._target = protected_route       # capture which route they tried to reach
        return html.Div([
            self.redirect(),
            html.Button("Log in as Alice", id=self.login_btn),
        ])

    def register_callbacks(self, app):
        @app.callback(
            Output(self.redirect.href_id, self.redirect.href_attr),
            Trigger(self.login_btn, "n_clicks"),
        )
        def login():
            session["user"] = "Alice"
            return {"url": self._target, "target": "_self"}


class Dashboard(WeaverletComponent):
    def get_layout(self, user):
        return html.Div(f"Welcome, {user}!")


class NotFound(WeaverletComponent):
    def get_layout(self, pathname):
        return html.Div(f"Page {pathname} not found")


router = AuthRouterComponent(
    routes={
        "/":          {"component": Dashboard(),  "login_required": True},
        "/login":     {"component": LoginPage(),  "login_required": False},
    },
    not_found_page_component=NotFound(),
)

WeaverletApp(root_component=router).app.run()

Visit /: unauthenticated, router redirects to /login. Click "Log in as Alice": session gets user="Alice", then redirect to / succeeds, dashboard renders "Welcome, Alice!"

The routes schema​

Each route value is a dict with two keys:

{"component": <WeaverletComponent>, "login_required": <bool>}

login_required=True routes are protected; login_required=False (typically the login page itself) are public.

What the router does on each request​

  1. Match the URL against routes.
  2. If the matched route has login_required=True:
    • Look for session[user_session_key] (default: "user").
    • If absent → render the login route's component, passing protected_route=<the original URL>.
    • If present → render the matched component, passing user=<value>.
  3. If login_required=False → render normally.

Kwargs the router injects​

In addition to SimpleRouterComponent's pathname, hash, href, search, the auth router can inject:

KwargWhat it isAvailable to
userThe session value (or None if not logged in)Any routed component
protected_routeThe original URL the visitor was trying to reachThe login page

As always, declare only what you need in get_layout: the router introspects your signature.

Customizing the session key and login route​

AuthRouterComponent(
    routes=...,
    not_found_page_component=...,
    user_session_key="current_user",     # default: "user"
    login_route="/signin",                # default: "/login"
)

keep_mounted and user​

AuthRouterComponent supports keep_mounted=True with the same semantics as SimpleRouterComponent. There's one subtle gotcha worth flagging:

When keep_mounted=True, all routes are pre-rendered at app startup. At that point, no one is logged in. So protected routes get user=None baked into their get_layout call. This means:

Don't capture user from get_layout under keep_mounted=True

The captured value will be None forever (set once at startup, never updated). Read flask.session[user_session_key] from inside your callbacks instead:

class Dashboard(WeaverletComponent):
    out_id = Identifier()
    btn_id = Identifier()

    def get_layout(self):
        return html.Div([html.Button("Show me", id=self.btn_id), html.Div(id=self.out_id)])

    def register_callbacks(self, app):
        @app.callback(Output(self.out_id, "children"), Input(self.btn_id, "n_clicks"),
                      prevent_initial_call=True)
        def show(_):
            from flask import session
            return f"Welcome, {session.get('user')}!"

The login-redirect pattern continues to work. The login wrapper's children are re-rendered on each protected-route redirect, so the protected_route capture in LoginPage still receives the right value.

If you don't need keep_mounted=True, the default keep_mounted=False mode is simpler and lets you safely capture user from get_layout.

Logging out​

There's no built-in logout. Write it yourself:

class NavbarComponent(WeaverletComponent):
    logout_btn = Identifier()

    def __init__(self):
        super().__init__()
        self.redirect = RedirectComponent()

    def get_layout(self):
        return html.Nav([
            self.redirect(),
            html.Button("Log out", id=self.logout_btn),
        ])

    def register_callbacks(self, app):
        @app.callback(
            Output(self.redirect.href_id, self.redirect.href_attr),
            Trigger(self.logout_btn, "n_clicks"),
        )
        def logout():
            session.pop("user", None)
            return {"url": "/login", "target": "_self"}

Security caveats​

  • Configure Flask's secret_key before deploying. Without it, sessions are unsigned and trivially forged. 
    wapp = WeaverletApp(root_component=router)
    wapp.app.server.secret_key = os.environ["FLASK_SECRET_KEY"]
  • HTTPS in production. Session cookies leak otherwise.
  • Don't store sensitive data in the session: Flask sessions are client-side by default (a signed cookie, but readable). Use flask.session for IDs that reference server-side state, not for raw secrets.
  • Auth is your responsibility. AuthRouterComponent does not authenticate users. It only checks that some session key exists. Your login callback decides whether the credentials were valid before setting the session.