Document mqtt state updates with empty or None values (#32864)

source/_integrations/alarm_control_panel.mqtt.markdown

@@ -246,7 +246,7 @@ retain:
   type: boolean
   default: false
 state_topic:
-  description: The MQTT topic subscribed to receive state updates.
+  description: The MQTT topic subscribed to receive state updates. A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: true
   type: string
 supported_features:

source/_integrations/climate.mqtt.markdown

@@ -29,8 +29,8 @@ action_template:
   type: template
 action_topic:
   description: >-
-    The MQTT topic to subscribe for changes of the current action. If this is set, the climate graph uses the value received as data source.
-    Valid values: `off`, `heating`, `cooling`, `drying`, `idle`, `fan`.
+    The MQTT topic to subscribe for changes of the current action. If this is set, the climate graph uses the value received as data source. A "None" payload resets the current action state. An empty payload is ignored.
+    Valid action values: `off`, `heating`, `cooling`, `drying`, `idle`, `fan`.
   required: false
   type: string
 availability:
@@ -161,7 +161,7 @@ fan_mode_state_template:
   required: false
   type: template
 fan_mode_state_topic:
-  description: The MQTT topic to subscribe for changes of the HVAC fan mode. If this is not set, the fan mode works in optimistic mode (see below).
+  description: The MQTT topic to subscribe for changes of the HVAC fan mode. If this is not set, the fan mode works in optimistic mode (see below). A "None" payload resets the fan mode state. An empty payload is ignored.
   required: false
   type: string
 fan_modes:
@@ -216,7 +216,7 @@ mode_state_template:
   required: false
   type: template
 mode_state_topic:
-  description: The MQTT topic to subscribe for changes of the HVAC operation mode. If this is not set, the operation mode works in optimistic mode (see below).
+  description: The MQTT topic to subscribe for changes of the HVAC operation mode. If this is not set, the operation mode works in optimistic mode (see below). A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: false
   type: string
 modes:

source/_integrations/cover.mqtt.markdown

@@ -257,7 +257,7 @@ state_stopped:
   type: string
   default: stopped
 state_topic:
-  description: The MQTT topic subscribed to receive cover state messages. State topic can only read (`open`, `opening`, `closed`, `closing` or `stopped`) state.
+  description: The MQTT topic subscribed to receive cover state messages. State topic can only read (`open`, `opening`, `closed`, `closing` or `stopped`) state.  A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: false
   type: string
 tilt_closed_value:

source/_integrations/device_tracker.mqtt.markdown

@@ -170,7 +170,7 @@ source_type:
   required: false
   type: string
 state_topic:
-  description: The MQTT topic subscribed to receive device tracker state changes. The states defined in `state_topic` override the location states defined by the `json_attributes_topic`. This state override is turned inactive if the `state_topic` receives a message containing `payload_reset`. The `state_topic` can only be omitted if `json_attributes_topic` is used.
+  description: The MQTT topic subscribed to receive device tracker state changes. The states defined in `state_topic` override the location states defined by the `json_attributes_topic`. This state override is turned inactive if the `state_topic` receives a message containing `payload_reset`. The `state_topic` can only be omitted if `json_attributes_topic` is used. An empty payload is ignored.
   required: false
   type: string
 unique_id:

source/_integrations/fan.mqtt.markdown

@@ -291,7 +291,7 @@ speed_range_min:
   type: integer
   default: 1
 state_topic:
-  description: The MQTT topic subscribed to receive state updates.
+  description: The MQTT topic subscribed to receive state updates. A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: false
   type: string
 state_value_template:

source/_integrations/humidifier.mqtt.markdown

@@ -273,7 +273,7 @@ retain:
   type: boolean
   default: true
 state_topic:
-  description: The MQTT topic subscribed to receive state updates.
+  description: The MQTT topic subscribed to receive state updates. A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: false
   type: string
 state_value_template:

source/_integrations/light.mqtt.markdown

@@ -359,7 +359,7 @@ schema:
   type: string
   default: default
 state_topic:
-  description: The MQTT topic subscribed to receive state updates.
+  description: The MQTT topic subscribed to receive state updates. A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: false
   type: string
 state_value_template:
@@ -706,7 +706,7 @@ schema:
   type: string
   default: default
 state_topic:
-  description: The MQTT topic subscribed to receive state updates.
+  description: The MQTT topic subscribed to receive state updates. A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: false
   type: string
 supported_color_modes:
@@ -1069,7 +1069,7 @@ state_template:
   required: false
   type: template
 state_topic:
-  description: The MQTT topic subscribed to receive state updates.
+  description: The MQTT topic subscribed to receive state updates. A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: false
   type: string
 unique_id:

source/_integrations/lock.mqtt.markdown

@@ -223,7 +223,7 @@ state_locking:
   type: string
   default: LOCKING
 state_topic:
-  description: The MQTT topic subscribed to receive state updates. It accepts states configured with `state_jammed`, `state_locked`, `state_unlocked`, `state_locking` or `state_unlocking`.
+  description: The MQTT topic subscribed to receive state updates. It accepts states configured with `state_jammed`, `state_locked`, `state_unlocked`, `state_locking` or `state_unlocking`. A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: false
   type: string
 state_unlocked:

source/_integrations/number.mqtt.markdown

@@ -181,7 +181,7 @@ retain:
   type: boolean
   default: false
 state_topic:
-  description: The MQTT topic subscribed to receive number values.
+  description: The MQTT topic subscribed to receive number values. An empty payload is ignored.
   required: false
   type: string
 step:

source/_integrations/select.mqtt.markdown

@@ -173,7 +173,7 @@ retain:
   type: boolean
   default: false
 state_topic:
-  description: The MQTT topic subscribed to receive update of the selected option.
+  description: The MQTT topic subscribed to receive update of the selected option. A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: false
   type: string
 unique_id:

source/_integrations/siren.mqtt.markdown

@@ -211,7 +211,7 @@ state_on:
   type: string
   default: "`payload_on` if defined, else `'ON'`"
 state_topic:
-  description: "The MQTT topic subscribed to receive state updates. The state update may be either JSON or a simple string. When a JSON payload is detected, the `state` value of the JSON payload should supply the `payload_on` or `payload_off` defined payload to turn the siren on or off. Additionally, the state attributes `duration`, `tone` and `volume_level` can be updated. Use `value_template` to transform the received state udpate to a compliant JSON payload. Attributes will only be set if the function is supported by the device and a valid value is supplied. When a non JSON payload is detected, it should be either of the `payload_on` or `payload_off` defined payloads or `None` to reset the siren's state to `unknown`. The initial state will be `unknown`. The state will be reset to `unknown` if a `None` payload or `null` JSON value is received as a state update."
+  description: "The MQTT topic subscribed to receive state updates. The state update may be either JSON or a simple string. When a JSON payload is detected, the `state` value of the JSON payload should supply the `payload_on` or `payload_off` defined payload to turn the siren on or off. Additionally, the state attributes `duration`, `tone` and `volume_level` can be updated. Use `value_template` to transform the received state update to a compliant JSON payload. Attributes will only be set if the function is supported by the device and a valid value is supplied. When a non JSON payload is detected, it should be either of the `payload_on` or `payload_off` defined payloads or `None` to reset the siren's state to `unknown`. The initial state will be `unknown`. The state will be reset to `unknown` if a `None` payload or `null` JSON value is received as a state update."
   required: false
   type: string
 state_value_template:

source/_integrations/switch.mqtt.markdown

@@ -202,7 +202,7 @@ state_on:
   type: string
   default: "`payload_on` if defined, else ON"
 state_topic:
-  description: The MQTT topic subscribed to receive state updates.
+  description: The MQTT topic subscribed to receive state updates. A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: false
   type: string
 unique_id:

source/_integrations/valve.mqtt.markdown

@@ -264,7 +264,7 @@ state_opening:
   type: string
   default: opening
 state_topic:
-  description: The MQTT topic subscribed to receive valve state messages. State topic accepts a state payload (`open`, `opening`, `closed`, or `closing`) or, if `reports_position` is supported, a numeric value representing the position. In a JSON format with variables `state` and `position` both values can received together.
+  description: The MQTT topic subscribed to receive valve state messages. State topic accepts a state payload (`open`, `opening`, `closed`, or `closing`) or, if `reports_position` is supported, a numeric value representing the position. In a JSON format with variables `state` and `position` both values can received together. A "None" state value resets to an `unknown` state. An empty string is ignored.
   required: false
   type: string
 unique_id:

source/_integrations/water_heater.mqtt.markdown

@@ -167,7 +167,7 @@ mode_state_template:
   required: false
   type: template
 mode_state_topic:
-  description: The MQTT topic to subscribe for changes of the water heater operation mode. If this is not set, the operation mode works in optimistic mode (see below).
+  description: The MQTT topic to subscribe for changes of the water heater operation mode. If this is not set, the operation mode works in optimistic mode (see below). A "None" payload resets to an `unknown` state. An empty payload is ignored.
   required: false
   type: string
 modes: