remove field name from HA discovery for single-field messages

ChangeLog.md

@@ -18,7 +18,7 @@
 * add option to discover device via mDNS
 * add dedicated log level for device messages
 * add option to extend MQTT variables from env/cmdline
-* add date+datetime mapping and better device update check to Home Assistant MQTT discovery integration
+* add date+datetime mapping, better device update check, and removed single-field-message field names to Home Assistant MQTT discovery integration
 
 ## Breaking Changes
 * change default config path to https://ebus.github.io/ serving files generated from new TypeSpec message definition sources

contrib/etc/ebusd/mqtt-hassio.cfg

@@ -52,6 +52,7 @@
 #   %field the field name and key for JSON objects (equals the field index if no name is defined or the names are not
 #     unique in the message).
 #   %fieldname the field name (and nothing else like in %field, might be empty though!)
+#   %fieldnamemult the field name unless there is a single field only (similar to %fieldname)
 #   %type the field type (one of "number", "list", "string", "date", "time", or "datetime").
 #   %basetype the base data type ID (e.g. "UCH").
 #   %comment the field comment (if any).
@@ -350,7 +351,7 @@ definition-topic ?= %haprefix/%type_topic/%{TOPIC}_%FIELD/config
 # HA integration: this is the config topic payload for HA's MQTT discovery.
 definition-payload = {
   "unique_id":"%{TOPIC}_%FIELD",
-  "name":"%name %fieldname",
+  "name":"%name %fieldnamemult",
   "device":%circuit_part,
   "value_template":"{{value_json[\"%field\"].value}}",
   "state_topic":"%topic"%field_payload

src/ebusd/mqtthandler.cpp

@@ -924,7 +924,9 @@ void MqttHandler::run() {
             StringReplacers values = msgValues;  // need a copy here as the contents are manipulated
             values.set("index", static_cast<signed>(index));
             values.set("field", fieldName);
-            values.set("fieldname", field->getName(-1));
+            string fieldNameNonUnique = field->getName(-1);
+            values.set("fieldname", fieldNameNonUnique);
+            values.set("fieldnamemult", fieldCount == 1 ? "" : fieldNameNonUnique);
             values.set("type", typeStr);
             values.set("type_map", str);
             values.set("basetype", dataType->getId());