snapshot of https://github.com/ThreeDotsLabs/watermill.git (master, 2026-09-15; blobs > 131072B omitted)

_examples/real-world-examples/consumer-groups/common/messaging.go

@@ -0,0 +1,46 @@
+package common
+
+import (
+	"encoding/json"
+	"strings"
+
+	"github.com/ThreeDotsLabs/watermill"
+	"github.com/ThreeDotsLabs/watermill/message"
+)
+
+const UpdatesTopic = "updates"
+
+func NotifyMiddleware(pub message.Publisher, serviceName string) func(message.HandlerFunc) message.HandlerFunc {
+	return func(next message.HandlerFunc) message.HandlerFunc {
+		return func(msg *message.Message) ([]*message.Message, error) {
+			topic := message.SubscribeTopicFromCtx(msg.Context())
+			handler := strings.Split(message.HandlerNameFromCtx(msg.Context()), "-")[0]
+
+			msgs, err := next(msg)
+			if err != nil {
+				return msgs, err
+			}
+
+			payload := MessageReceived{
+				ID:      msg.UUID,
+				Service: serviceName,
+				Handler: handler,
+				Topic:   topic,
+			}
+
+			jsonPayload, err := json.Marshal(payload)
+			if err != nil {
+				return nil, err
+			}
+
+			newMsg := message.NewMessage(watermill.NewUUID(), jsonPayload)
+
+			err = pub.Publish(UpdatesTopic, newMsg)
+			if err != nil {
+				return nil, err
+			}
+
+			return msgs, nil
+		}
+	}
+}