Error Handling

🧯 Error Handling

Zuno gives you full control over how errors are handled—whether it’s a missing route, a failed validation, or an unexpected exception. You can send custom responses, set status codes, and define global error middleware.

❌ Sending Error Responses

You can send an error response from any route handler using res.status() and res.send():

app.get("/protected", [](auto& req, auto& res) {
if (!req.headers.contains("Authorization")) {
  res.status(401).send("Unauthorized");
  return;
}

res.send("Welcome!");
});

🔍 Handling Not Found (404)

Zuno automatically returns a 404 if no route matches the request. You can override this with a fallback handler:

app.use([](auto& req, auto& res, auto next) {
res.status(404).send("Route not found");
});

🧱 Global Error Middleware

You can define a middleware to catch and handle errors across your app. This is useful for logging, masking internal errors, or returning consistent error formats.

Middleware errorHandler = [](auto& req, auto& res, auto next) {
try {
  next(); // Run the next middleware or route
} catch (const std::exception& ex) {
  res.status(500).send("Internal Server Error");
  std::cerr << "Unhandled error: " << ex.what() << std::endl;
}
};

app.use(errorHandler);

🧪 Custom Error Pages

You can return HTML or JSON depending on the client:

app.use([](auto& req, auto& res, auto next) {
res.status(404).json({{"error","Not Found"}});
});

Or return structured JSON for APIs:

res.status(400).json({
{"error", "Invalid input"}
{"code", 400}
});

🧭 Best Practices

Always return meaningful status codes (e.g. 400, 401, 404, 500)
Avoid exposing internal error messages in production
Use global error middleware to centralize logging and response formatting
Provide consistent error structures for frontend or API clients

🧭 Next Steps

Now that you can handle errors gracefully, explore:

Zuno helps you fail gracefully—because great DX includes great error handling.