An IQ can only have a single payload

"An IQ stanza of type "get" or "set" MUST contain exactly one
 child element, which specifies the semantics of the particular
 request."

client_test.go

@@ -198,7 +198,7 @@ func bind(t *testing.T, c net.Conn, decoder *xml.Decoder) {
 	}
 
 	// TODO Check all elements
-	switch iq.Payload[0].(type) {
+	switch iq.Payload.(type) {
 	case *BindBind:
 		result := `<iq id='%s' type='result'>
   <bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>

component_test.go

@@ -78,18 +78,16 @@ func TestParsingDelegationIQ(t *testing.T) {
 
 	// Check that we have extracted the delegation info as IQPayload
 	var node string
-	for _, ext := range iq.Payload {
-		if delegation, ok := ext.(*Delegation); ok {
+	if iq.Payload != nil {
+		if delegation, ok := iq.Payload.(*Delegation); ok {
 			packet := delegation.Forwarded.Stanza
 			forwardedIQ, ok := packet.(IQ)
 			if !ok {
 				t.Errorf("Could not extract packet IQ")
 				return
 			}
-			payload := forwardedIQ.Payload
-			if len(payload) > 0 {
-				pl := payload[0]
-				if pubsub, ok := pl.(*PubSub); ok {
+			if forwardedIQ.Payload != nil {
+				if pubsub, ok := forwardedIQ.Payload.(*PubSub); ok {
 					node = pubsub.Publish.Node
 				}
 			}

iot_control_test.go

@@ -20,7 +20,7 @@ func TestControlSet(t *testing.T) {
 		t.Errorf("Unmarshal(%s) returned error", data)
 	}
 
-	if cs, ok := parsedIQ.Payload[0].(*ControlSet); !ok {
+	if cs, ok := parsedIQ.Payload.(*ControlSet); !ok {
 		t.Errorf("Paylod is not an iot control set: %v", cs)
 	}
 }

iq.go

@@ -123,13 +123,13 @@ func (x Err) MarshalXML(e *xml.Encoder, start xml.StartElement) (err error) {
 type IQ struct { // Info/Query
 	XMLName xml.Name `xml:"iq"`
 	PacketAttrs
-	// FIXME: We can only have one payload:
+	// We can only have one payload on IQ:
 	//   "An IQ stanza of type "get" or "set" MUST contain exactly one
 	//    child element, which specifies the semantics of the particular
 	//    request."
-	Payload []IQPayload `xml:",omitempty"`
-	RawXML  string      `xml:",innerxml"`
+	Payload IQPayload `xml:",omitempty"`
 	Error   Err       `xml:"error,omitempty"`
+	RawXML  string    `xml:",innerxml"`
 }
 
 func NewIQ(iqtype, from, to, id, lang string) IQ {
@@ -145,10 +145,6 @@ func NewIQ(iqtype, from, to, id, lang string) IQ {
 	}
 }
 
-func (iq *IQ) AddPayload(payload IQPayload) {
-	iq.Payload = append(iq.Payload, payload)
-}
-
 func (iq IQ) MakeError(xerror Err) IQ {
 	from := iq.From
 	to := iq.To
@@ -217,7 +213,7 @@ func (iq *IQ) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 					if err != nil {
 						return err
 					}
-					iq.Payload = append(iq.Payload, iqExt)
+					iq.Payload = iqExt
 				} else {
 					// TODO: Fix me. We do nothing of that element here.
 					// elt = new(Node)

iq_test.go

@@ -47,7 +47,7 @@ func TestGenerateIq(t *testing.T) {
 			{Var: xmpp.NSDiscoItems},
 		},
 	}
-	iq.AddPayload(&payload)
+	iq.Payload = &payload
 
 	data, err := xml.Marshal(iq)
 	if err != nil {
@@ -97,7 +97,7 @@ func TestDiscoItems(t *testing.T) {
 	payload := xmpp.DiscoItems{
 		Node: "music",
 	}
-	iq.AddPayload(&payload)
+	iq.Payload = &payload
 
 	data, err := xml.Marshal(iq)
 	if err != nil {
@@ -123,7 +123,7 @@ func TestUnmarshalPayload(t *testing.T) {
 		t.Errorf("Unmarshal(%s) returned error", query)
 	}
 
-	if len(parsedIQ.Payload) != 1 {
-		t.Errorf("Incorrect payload size: %d", len(parsedIQ.Payload))
+	if parsedIQ.Payload == nil {
+		t.Error("Missing payload")
 	}
 }

router.go

@@ -157,10 +157,10 @@ func (m nsIQMatcher) Match(p Packet, match *RouteMatch) bool {
 	if !ok {
 		return false
 	}
-	if len(iq.Payload) < 1 {
+	if iq.Payload == nil {
 		return false
 	}
-	return matchInArray(m, iq.Payload[0].Namespace())
+	return matchInArray(m, iq.Payload.Namespace())
 }
 
 // IQNamespaces adds an IQ matcher, expecting both an IQ and a

router_test.go

@@ -33,7 +33,7 @@ func TestNameMatcher(t *testing.T) {
 	// Check that an IQ packet is not matched
 	conn = NewSenderMock()
 	iq := xmpp.NewIQ("get", "", "localhost", "1", "")
-	iq.Payload = append(iq.Payload, &xmpp.DiscoInfo{})
+	iq.Payload = &xmpp.DiscoInfo{}
 	router.Route(conn, iq)
 	if conn.String() == successFlag {
 		t.Error("IQ should not have been matched and routed")
@@ -52,11 +52,11 @@ func TestIQNSMatcher(t *testing.T) {
 	conn := NewSenderMock()
 	iqDisco := xmpp.NewIQ("get", "", "localhost", "1", "")
 	// TODO: Add a function to generate payload with proper namespace initialisation
-	iqDisco.Payload = append(iqDisco.Payload, &xmpp.DiscoInfo{
+	iqDisco.Payload = &xmpp.DiscoInfo{
 		XMLName: xml.Name{
 			Space: xmpp.NSDiscoInfo,
 			Local: "query",
-		}})
+		}}
 	router.Route(conn, iqDisco)
 	if conn.String() != successFlag {
 		t.Errorf("IQ should have been matched and routed: %v", iqDisco)
@@ -66,11 +66,11 @@ func TestIQNSMatcher(t *testing.T) {
 	conn = NewSenderMock()
 	iqVersion := xmpp.NewIQ("get", "", "localhost", "1", "")
 	// TODO: Add a function to generate payload with proper namespace initialisation
-	iqVersion.Payload = append(iqVersion.Payload, &xmpp.DiscoInfo{
+	iqVersion.Payload = &xmpp.DiscoInfo{
 		XMLName: xml.Name{
 			Space: "jabber:iq:version",
 			Local: "query",
-		}})
+		}}
 	router.Route(conn, iqVersion)
 	if conn.String() == successFlag {
 		t.Errorf("IQ should not have been matched and routed: %v", iqVersion)

session.go

@@ -165,7 +165,7 @@ func (s *Session) bind(o Config) {
 	}
 
 	// TODO Check all elements
-	switch payload := iq.Payload[0].(type) {
+	switch payload := iq.Payload.(type) {
 	case *BindBind:
 		s.BindJid = payload.Jid // our local id (with possibly randomly generated resource
 	default: