Attribute Macro on 

#[on]

Defines Socket.IO handlers for its associated adapter. This macro should be used inside an impl block of a struct annotated with the #[socketio_adapter] macro.

Parameters

• path: The path for the Socket.IO endpoint, e.g., "/socket"

Usage

#[socketio_adapter("/socket")]
struct SocketController;

#[handlers]
impl SocketController {
    #[on_connection]
    async fn on_connect(&self, socket: SocketRef) {
        println!("Client connected");
    }

    #[on_message("message")]
    async fn on_message(&self, socket: SocketRef, Data(msg): Data<String>) {
        println!("Received: {}", msg);
    }

    #[on_disconnect]
    async fn on_disconnect(&self, socket: SocketRef) {
        println!("Client disconnected");
    }
}

Unified handler attribute for Socket.IO events.

Event Types

• #[on("connection")] - Called when a client connects
• #[on("disconnection")] - Called when a client disconnects
• #[on("fallback")] - Called for unhandled events
• #[on("custom_event")] - Called for custom event names

Parameters

All handlers receive &self and ctx: SocketContext which provides access to:

• Socket operations via ctx.socket
• Message data via ctx.try_data::<T>()
• Event name via ctx.event()
• Acknowledgments via ctx.ack()

Usage

#[socketio_adapter("/chat")]
pub struct ChatAdapter { ... }

impl ChatAdapter {
    #[on("connection")]
    async fn on_connect(&self, ctx: SocketContext) {
        println!("Client connected: {}", ctx.socket.id);
    }
     
    #[on("message")]
    async fn handle_message(&self, ctx: SocketContext) {
        let msg: String = ctx.try_data().unwrap();
        println!("Received: {}", msg);
    }
}