Mqtt: fix forecast no longer published (#24483)

api/marshal.go

@@ -0,0 +1,11 @@
+package api
+
+// BytesMarshaler marshals into bytes/string representation
+type BytesMarshaler interface {
+	MarshalBytes() ([]byte, error)
+}
+
+// BytesMarshaler marshals into a struct representation
+type StructMarshaler interface {
+	MarshalStruct() (any, error)
+}

api/rates.go

@@ -47,7 +47,9 @@ func (rr Rates) At(ts time.Time) (Rate, error) {
 	return Rate{}, ErrNotAvailable
 }
 
-// MarshalMQTT implements server.MQTTMarshaler
-func (r Rates) MarshalMQTT() ([]byte, error) {
+var _ BytesMarshaler = Rates{}
+
+// MarshalBytes implements server.BytesMarshaler
+func (r Rates) MarshalBytes() ([]byte, error) {
 	return json.Marshal(r)
 }

server/mqtt.go

@@ -18,12 +18,6 @@ import (
 	"github.com/samber/lo"
 )
 
-// MQTTMarshaler is the interface implemented by types that
-// can marshal themselves into valid an MQTT string representation.
-type MQTTMarshaler interface {
-	MarshalMQTT() ([]byte, error)
-}
-
 // MQTT is the MQTT server. It uses the MQTT client for publishing.
 type MQTT struct {
 	log       *util.Logger
@@ -91,15 +85,25 @@ func (m *MQTT) publishComplex(topic string, retained bool, payload interface{})
 		return
 	}
 
-	if mm, ok := payload.(MQTTMarshaler); ok {
-		if b, err := mm.MarshalMQTT(); err == nil {
+	if mm, ok := payload.(api.BytesMarshaler); ok {
+		if b, err := mm.MarshalBytes(); err == nil {
 			m.publishSingleValue(topic, retained, string(b))
 		} else {
-			m.log.ERROR.Printf("marshal mqtt: %v", err)
+			m.log.ERROR.Printf("marshal bytes: %v", err)
 		}
 		return
 	}
 
+	if mm, ok := payload.(api.StructMarshaler); ok {
+		if d, err := mm.MarshalStruct(); err != nil {
+			m.log.ERROR.Printf("marshal struct: %v", err)
+			return
+		} else {
+			payload = d
+			// fallthrough
+		}
+	}
+
 	switch typ := reflect.TypeOf(payload); typ.Kind() {
 	case reflect.Slice:
 		// publish count

util/param_shard.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/evcc-io/evcc/api"
 	"github.com/fatih/structs"
 )
 
@@ -72,6 +73,12 @@ func (s *sharderImpl) Shards() []Shard {
 	return res
 }
 
+var _ api.StructMarshaler = (*sharderImpl)(nil)
+
+func (s *sharderImpl) MarshalStruct() (any, error) {
+	return s.struc, nil
+}
+
 var _ Sharder = (*sharderImpl)(nil)
 
 // NewSharder creates a Sharder that splits structs into sub-structs for space-efficient socket publishing