This example demonstrates how to use Group.SetNotFoundHandle to set custom 404 handlers for router groups.
- Group-level 404 handler: Set custom 404 response for specific route groups
- Priority: Group-level handler takes priority over app-level handler
- Flexible: Different groups can have different 404 handlers
# Run the example
go run main.go
# Test routes
curl http://localhost:8080/ # Welcome page
curl http://localhost:8080/api/users # API: Users list
curl http://localhost:8080/api/health # API: Health check
curl http://localhost:8080/api/unknown # API: 404 (group handler)
curl http://localhost:8080/web/index # Web: Index page
curl http://localhost:8080/web/unknown # Web: 404 (global handler)
curl http://localhost:8080/unknown # Global: 404 (global handler)$ curl http://localhost:8080/api/unknown
{"code": 404, "message": "API 404 - Resource not found", "hint": "Check API documentation for available endpoints"}$ curl http://localhost:8080/web/unknown
{"code": 404, "message": "Global 404 - Page not found"}$ curl http://localhost:8080/unknown
{"code": 404, "message": "Global 404 - Page not found"}// Set global 404 handler (fallback)
app.SetNotFoundHandle(func(ctx dotweb.Context) error {
return ctx.WriteString(`{"code": 404, "message": "Global 404"}`)
})
// Create API group with custom 404 handler
apiGroup := app.HttpServer.Group("/api")
apiGroup.SetNotFoundHandle(func(ctx dotweb.Context) error {
return ctx.WriteString(`{"code": 404, "message": "API 404"}`)
})
// Web group uses global 404 (no SetNotFoundHandle)
webGroup := app.HttpServer.Group("/web")- API vs Web: Return JSON for API 404s, HTML for Web 404s
- Versioned APIs: Different 404 messages for v1 vs v2 APIs
- Multi-tenant: Custom 404 per tenant group
- Internationalization: Different language 404 messages per group