Messages

The Message type represents incoming WebSocket messages with helpers for common formats.

import "github.com/KARTIKrocks/wshub"

• Typed message representation (text and binary)
• Convenience helpers for text and JSON parsing
• Includes sender client ID and receive timestamp
• Pre-serialized JSON API for zero-alloc fan-out (~35 ns per send)

Exact signatures live on pkg.go.dev.

Message Type

Field / Method	Description
Type	MessageType (TextMessage or BinaryMessage)
Data	Raw message data as []byte
ClientID	Sender's client ID
Time	Receive timestamp
Text()	Data as a string
JSON(v)	Unmarshal data as JSON into v

type Message struct {
    Type     MessageType // TextMessage, BinaryMessage
    Data     []byte      // Raw message data
    ClientID string      // Sender's client ID
    Time     time.Time   // Receive timestamp
}

// Convenience helpers
text := msg.Text()         // Data as string

var payload ChatMessage
err := msg.JSON(&payload)  // Unmarshal as JSON

Changed in 1.8. JSON(v) and NewJSONMessage now use encoding/json/v2 semantics: JSON object member names are matched case-sensitively, duplicate object member names are rejected, and invalid UTF-8 in a JSON string is rejected. Previously, member matching was case-insensitive, a duplicate name silently kept the last value, and invalid UTF-8 was silently replaced with U+FFFD. Payloads whose field names already match your struct tags exactly are unaffected.

Message Handler

Set a message handler when creating the hub to process incoming messages:

hub := wshub.NewHub(
    wshub.WithMessageHandler(func(client *wshub.Client, msg *wshub.Message) error {
        // Parse the incoming message
        var chatMsg struct {
            Room string `json:"room"`
            Text string `json:"text"`
        }
        if err := msg.JSON(&chatMsg); err != nil {
            return err
        }

        // Broadcast to a room
        response, _ := json.Marshal(map[string]string{
            "from": client.ID,
            "text": chatMsg.Text,
        })
        hub.BroadcastToRoom(chatMsg.Room, response)
        return nil
    }),
)

Pre-serialized JSON

When you marshal JSON once and fan it out to many clients, use the raw JSON API to skip re-serialization entirely. This is ideal for high-throughput broadcast patterns where the same payload goes to hundreds or thousands of connections.

Function / Method	Description
NewRawJSONMessage(data)	Create a message from already-marshaled JSON bytes
Hub.BroadcastRawJSON(data)	Broadcast pre-serialized JSON to all clients
Client.SendRawJSON(data)	Send pre-serialized JSON to a single client

// Marshal once, broadcast to all — 0 allocs per send (~35 ns vs ~1,000 ns)
data, _ := json.Marshal(map[string]any{
    "type":    "position",
    "x":       player.X,
    "y":       player.Y,
    "playerID": player.ID,
})

// Fan out pre-serialized bytes (no per-client json.Marshal)
hub.BroadcastRawJSON(data)

// Or send to a single client
client.SendRawJSON(data)