Command retain option for MQTT component (#3078)

esphome/components/mqtt/__init__.py

@@ -11,6 +11,7 @@ from esphome.const import (
     CONF_BROKER,
     CONF_CLIENT_ID,
     CONF_COMMAND_TOPIC,
+    CONF_COMMAND_RETAIN,
     CONF_DISCOVERY,
     CONF_DISCOVERY_PREFIX,
     CONF_DISCOVERY_RETAIN,
@@ -392,6 +393,8 @@ async def register_mqtt_component(var, config):
         cg.add(var.set_custom_state_topic(config[CONF_STATE_TOPIC]))
     if CONF_COMMAND_TOPIC in config:
         cg.add(var.set_custom_command_topic(config[CONF_COMMAND_TOPIC]))
+    if CONF_COMMAND_RETAIN in config:
+        cg.add(var.set_command_retain(config[CONF_COMMAND_RETAIN]))
     if CONF_AVAILABILITY in config:
         availability = config[CONF_AVAILABILITY]
         if not availability:

esphome/components/mqtt/mqtt_component.cpp

@@ -92,6 +92,8 @@ bool MQTTComponent::send_discovery_() {
           root[MQTT_STATE_TOPIC] = this->get_state_topic_();
         if (config.command_topic)
           root[MQTT_COMMAND_TOPIC] = this->get_command_topic_();
+        if (this->command_retain_)
+          root[MQTT_COMMAND_RETAIN] = true;
 
         if (this->availability_ == nullptr) {
           if (!global_mqtt_client->get_availability().topic.empty()) {
@@ -165,6 +167,7 @@ void MQTTComponent::set_custom_state_topic(const std::string &custom_state_topic
 void MQTTComponent::set_custom_command_topic(const std::string &custom_command_topic) {
   this->custom_command_topic_ = custom_command_topic;
 }
+void MQTTComponent::set_command_retain(bool command_retain) { this->command_retain_ = command_retain; }
 
 void MQTTComponent::set_availability(std::string topic, std::string payload_available,
                                      std::string payload_not_available) {

esphome/components/mqtt/mqtt_component.h

@@ -91,6 +91,8 @@ class MQTTComponent : public Component {
   void set_custom_state_topic(const std::string &custom_state_topic);
   /// Set a custom command topic. Set to "" for default behavior.
   void set_custom_command_topic(const std::string &custom_command_topic);
+  /// Set whether command message should be retained.
+  void set_command_retain(bool command_retain);
 
   /// MQTT_COMPONENT setup priority.
   float get_setup_priority() const override;
@@ -188,6 +190,7 @@ class MQTTComponent : public Component {
 
   std::string custom_state_topic_{};
   std::string custom_command_topic_{};
+  bool command_retain_{false};
   bool retain_{true};
   bool discovery_enabled_{true};
   std::unique_ptr<Availability> availability_;

esphome/components/mqtt/mqtt_const.h

@@ -45,6 +45,7 @@ constexpr const char *const MQTT_CLEANING_TEMPLATE = "cln_tpl";
 constexpr const char *const MQTT_COMMAND_OFF_TEMPLATE = "cmd_off_tpl";
 constexpr const char *const MQTT_COMMAND_ON_TEMPLATE = "cmd_on_tpl";
 constexpr const char *const MQTT_COMMAND_TOPIC = "cmd_t";
+constexpr const char *const MQTT_COMMAND_RETAIN = "ret";
 constexpr const char *const MQTT_COMMAND_TEMPLATE = "cmd_tpl";
 constexpr const char *const MQTT_CODE_ARM_REQUIRED = "cod_arm_req";
 constexpr const char *const MQTT_CODE_DISARM_REQUIRED = "cod_dis_req";
@@ -297,6 +298,7 @@ constexpr const char *const MQTT_CLEANING_TEMPLATE = "cleaning_template";
 constexpr const char *const MQTT_COMMAND_OFF_TEMPLATE = "command_off_template";
 constexpr const char *const MQTT_COMMAND_ON_TEMPLATE = "command_on_template";
 constexpr const char *const MQTT_COMMAND_TOPIC = "command_topic";
+constexpr const char *const MQTT_COMMAND_RETAIN = "retain";
 constexpr const char *const MQTT_COMMAND_TEMPLATE = "command_template";
 constexpr const char *const MQTT_CODE_ARM_REQUIRED = "code_arm_required";
 constexpr const char *const MQTT_CODE_DISARM_REQUIRED = "code_disarm_required";

esphome/config_validation.py

@@ -17,6 +17,7 @@ from esphome.const import (
     ALLOWED_NAME_CHARS,
     CONF_AVAILABILITY,
     CONF_COMMAND_TOPIC,
+    CONF_COMMAND_RETAIN,
     CONF_DISABLED_BY_DEFAULT,
     CONF_DISCOVERY,
     CONF_ENTITY_CATEGORY,
@@ -1591,6 +1592,7 @@ MQTT_COMPONENT_SCHEMA = Schema(
 MQTT_COMMAND_COMPONENT_SCHEMA = MQTT_COMPONENT_SCHEMA.extend(
     {
         Optional(CONF_COMMAND_TOPIC): All(requires_component("mqtt"), subscribe_topic),
+        Optional(CONF_COMMAND_RETAIN): All(requires_component("mqtt"), boolean),
     }
 )
 

esphome/const.py

@@ -106,6 +106,7 @@ CONF_COLOR_MODE = "color_mode"
 CONF_COLOR_TEMPERATURE = "color_temperature"
 CONF_COLORS = "colors"
 CONF_COMMAND = "command"
+CONF_COMMAND_RETAIN = "command_retain"
 CONF_COMMAND_TOPIC = "command_topic"
 CONF_COMMENT = "comment"
 CONF_COMMIT = "commit"