Misc fixes for events

v2/internal/messagedispatcher/message/event.go

@@ -13,6 +13,7 @@ type EventMessage struct {
 type OnEventMessage struct {
 	Name     string
 	Callback func(optionalData ...interface{})
+	Counter  int
 }
 
 // eventMessageParser does what it says on the tin!
@@ -28,8 +29,6 @@ func eventMessageParser(message string) (*parsedMessage, error) {
 
 	// Switch the event type (with or without data)
 	switch message[0] {
-	case 'e':
-		eventMessage.Name = message[2:]
 	case 'E':
 		m := message[2:]
 		err := json.Unmarshal([]byte(m), eventMessage)

v2/internal/runtime/goruntime/events.go

@@ -8,6 +8,7 @@ import (
 // Events defines all events related operations
 type Events interface {
 	On(eventName string, callback func(optionalData ...interface{}))
+	Once(eventName string, callback func(optionalData ...interface{}))
 	Emit(eventName string, optionalData ...interface{})
 }
 
@@ -28,6 +29,17 @@ func (r *event) On(eventName string, callback func(optionalData ...interface{}))
 	eventMessage := &message.OnEventMessage{
 		Name:     eventName,
 		Callback: callback,
+		Counter:  -1,
+	}
+	r.bus.Publish("event:on", eventMessage)
+}
+
+// On pass through
+func (r *event) Once(eventName string, callback func(optionalData ...interface{})) {
+	eventMessage := &message.OnEventMessage{
+		Name:     eventName,
+		Callback: callback,
+		Counter:  1,
 	}
 	r.bus.Publish("event:on", eventMessage)
 }

v2/internal/runtime/js/core/events.js

@@ -137,17 +137,11 @@ export function Notify(notifyMessage) {
  */
 export function Emit(eventName) {
 
-	// Calculate the data
+	const payload = {
-	if (arguments.length > 1) {
+		name: eventName,
-		// Notify backend
+		data: [].slice.apply(arguments).slice(1),
-		const payload = {
+	};
-			name: eventName,
+	SendMessage('Ej' + JSON.stringify(payload));
-			data: [].slice.apply(arguments).slice(1),
-		};
-		SendMessage('Ej' + JSON.stringify(payload));
-	} else {
-		SendMessage('ej' + eventName);
-	}
 
 }
 

v2/internal/subsystem/event.go

@@ -15,7 +15,7 @@ import (
 // means it does not expire (default).
 type eventListener struct {
 	callback func(...interface{}) // Function to call with emitted event data
-	counter  int64                // The number of times this callback may be called. -1 = infinite
+	counter  int                  // The number of times this callback may be called. -1 = infinite
 	delete   bool                 // Flag to indicate that this listener should be deleted
 }
 
@@ -60,12 +60,12 @@ func NewEvent(bus *servicebus.ServiceBus, logger *logger.Logger) (*Event, error)
 }
 
 // RegisterListener provides a means of subscribing to events of type "eventName"
-func (e *Event) RegisterListener(eventName string, callback func(...interface{})) {
+func (e *Event) RegisterListener(eventName string, callback func(...interface{}), counter int) {
 
 	// Create new eventListener
 	thisListener := &eventListener{
 		callback: callback,
-		counter:  0,
+		counter:  counter,
 		delete:   false,
 	}
 
@@ -120,7 +120,7 @@ func (e *Event) Start() error {
 					var message *message.OnEventMessage = eventMessage.Data().(*message.OnEventMessage)
 					eventName := message.Name
 					callback := message.Callback
-					e.RegisterListener(eventName, callback)
+					e.RegisterListener(eventName, callback, message.Counter)
 					e.logger.Trace("Registered listener for event '%s' with callback %p", eventName, callback)
 				default:
 					e.logger.Error("unknown event message: %+v", eventMessage)
@@ -179,13 +179,16 @@ func (e *Event) notifyListeners(eventName string, message *message.EventMessage)
 			}
 		}
 
-		// Save new listeners
+		// Save new listeners or remove entry
-		e.listeners[eventName] = newListeners
+		if len(newListeners) > 0 {
+			e.listeners[eventName] = newListeners
+		} else {
+			delete(e.listeners, eventName)
+		}
 	}
 
 	// Unlock
 	e.notifyLock.Unlock()
-
 }
 
 func (e *Event) shutdown() {

v2/test/runtime/runtime.go

@@ -23,6 +23,9 @@ func (r *RuntimeTest) WailsInit(runtime *wails.Runtime) error {
 	r.runtime.Events.On("testevent", func(optionalParams ...interface{}) {
 		println("Wooohoooo! I got called!")
 	})
+	r.runtime.Events.Once("testeventonce", func(optionalParams ...interface{}) {
+		println("I only get called once!")
+	})
 	return nil
 }