Correctly allow mqtt topics to be none so ESPHome does not sub/pub to them (#5213)

esphome/components/mqtt/mqtt_component.cpp

@@ -2,9 +2,9 @@
 
 #ifdef USE_MQTT
 
-#include "esphome/core/log.h"
 #include "esphome/core/application.h"
 #include "esphome/core/helpers.h"
+#include "esphome/core/log.h"
 #include "esphome/core/version.h"
 
 #include "mqtt_const.h"
@@ -28,15 +28,15 @@ std::string MQTTComponent::get_default_topic_for_(const std::string &suffix) con
 }
 
 std::string MQTTComponent::get_state_topic_() const {
-  if (this->custom_state_topic_.empty())
-    return this->get_default_topic_for_("state");
+  if (this->has_custom_state_topic_)
     return this->custom_state_topic_;
+  return this->get_default_topic_for_("state");
 }
 
 std::string MQTTComponent::get_command_topic_() const {
-  if (this->custom_command_topic_.empty())
-    return this->get_default_topic_for_("command");
+  if (this->has_custom_command_topic_)
     return this->custom_command_topic_;
+  return this->get_default_topic_for_("command");
 }
 
 bool MQTTComponent::publish(const std::string &topic, const std::string &payload) {
@@ -171,9 +171,11 @@ float MQTTComponent::get_setup_priority() const { return setup_priority::AFTER_C
 void MQTTComponent::disable_discovery() { this->discovery_enabled_ = false; }
 void MQTTComponent::set_custom_state_topic(const std::string &custom_state_topic) {
   this->custom_state_topic_ = custom_state_topic;
+  this->has_custom_state_topic_ = true;
 }
 void MQTTComponent::set_custom_command_topic(const std::string &custom_command_topic) {
   this->custom_command_topic_ = custom_command_topic;
+  this->has_custom_command_topic_ = true;
 }
 void MQTTComponent::set_command_retain(bool command_retain) { this->command_retain_ = command_retain; }
 
@@ -240,7 +242,20 @@ bool MQTTComponent::is_connected_() const { return global_mqtt_client->is_connec
 std::string MQTTComponent::friendly_name() const { return this->get_entity()->get_name(); }
 std::string MQTTComponent::get_icon() const { return this->get_entity()->get_icon(); }
 bool MQTTComponent::is_disabled_by_default() const { return this->get_entity()->is_disabled_by_default(); }
-bool MQTTComponent::is_internal() { return this->get_entity()->is_internal(); }
+bool MQTTComponent::is_internal() {
+  if ((this->get_state_topic_().empty()) || (this->get_command_topic_().empty())) {
+    // If both state_topic and command_topic are empty, then the entity is internal to mqtt
+    return true;
+  }
+
+  if (this->has_custom_state_topic_ || this->has_custom_command_topic_) {
+    // If a custom state_topic or command_topic is set, then the entity is not internal to mqtt
+    return false;
+  }
+
+  // Use ESPHome's entity internal state
+  return this->get_entity()->is_internal();
+}
 
 }  // namespace mqtt
 }  // namespace esphome

esphome/components/mqtt/mqtt_component.h

@@ -190,6 +190,9 @@ class MQTTComponent : public Component {
 
   std::string custom_state_topic_{};
   std::string custom_command_topic_{};
+  bool has_custom_state_topic_{false};
+  bool has_custom_command_topic_{false};
+
   bool command_retain_{false};
   bool retain_{true};
   bool discovery_enabled_{true};

esphome/config_validation.py

@@ -1047,6 +1047,8 @@ def ipv4(value):
 
 def _valid_topic(value):
     """Validate that this is a valid topic name/filter."""
+    if value is None:  # Used to disable publishing and subscribing
+        return ""
     if isinstance(value, dict):
         raise Invalid("Can't use dictionary with topic")
     value = string(value)

tests/test5.yaml

@@ -64,6 +64,7 @@ mqtt:
   discovery: true
   discovery_prefix: homeassistant
   idf_send_async: false
+  log_topic:
   on_message:
     topic: testing/sensor/testing_sensor/state
     qos: 0
@@ -403,6 +404,7 @@ sensor:
     update_interval: 1s
   - platform: internal_temperature
     name: Internal Temperature
+    state_topic:
   - platform: selec_meter
     total_active_energy:
       name: SelecEM2M Total Active Energy