Exceptions ¶

Stario uses exceptions to handle HTTP errors and domain-specific failures.

HttpException ¶

Raise HttpException to stop execution and return an HTTP error.

from stario import HttpException

async def get_user(c: Context, w: Writer):
    user = await db.find(c.req.tail)
    if not user:
        raise HttpException(404, "User not found")
    w.json(user)

Global Error Handlers ¶

Register custom handlers to catch exceptions and return beautiful error pages or JSON.

def handle_404(c: Context, w: Writer, exc: HttpException):
    w.html(Div(H1("Oops!"), P(exc.detail)), status=404)

def handle_generic(c: Context, w: Writer, exc: Exception):
    # Log the real error to your tracer
    c["error"] = str(exc)
    w.json({"error": "Internal Server Error"}, status=500)

app.on_error(HttpException, handle_404)
app.on_error(Exception, handle_generic)

ClientDisconnected ¶

Raised automatically when a client closes the connection during an SSE stream. If you use w.alive(), this is handled for you and the loop simply exits.

async def stream(c: Context, w: Writer):
    async for msg in w.alive(relay.subscribe("chat")):
        w.patch(Div(msg))
    # Disconnect happens -> loop ends -> cleanup runs here

StarioError ¶

Internal framework errors (e.g., misconfiguration). These usually include help_text to guide you toward a fix.