Add value_template option to KNX expose (#117732)

* Add value_template option to KNX expose

* template exception handling

homeassistant/components/knx/expose.py

@@ -13,6 +13,7 @@ from xknx.remote_value import RemoteValueSensor
 
 from homeassistant.const import (
     CONF_ENTITY_ID,
+    CONF_VALUE_TEMPLATE,
     STATE_OFF,
     STATE_ON,
     STATE_UNAVAILABLE,
@@ -25,7 +26,9 @@ from homeassistant.core import (
     State,
     callback,
 )
+from homeassistant.exceptions import TemplateError
 from homeassistant.helpers.event import async_track_state_change_event
+from homeassistant.helpers.template import Template
 from homeassistant.helpers.typing import ConfigType, StateType
 
 from .const import CONF_RESPOND_TO_READ, KNX_ADDRESS
@@ -79,6 +82,9 @@ class KNXExposeSensor:
         )
         self.expose_default = config.get(ExposeSchema.CONF_KNX_EXPOSE_DEFAULT)
         self.expose_type: int | str = config[ExposeSchema.CONF_KNX_EXPOSE_TYPE]
+        self.value_template: Template | None = config.get(CONF_VALUE_TEMPLATE)
+        if self.value_template is not None:
+            self.value_template.hass = hass
 
         self._remove_listener: Callable[[], None] | None = None
         self.device: ExposeSensor = self.async_register(config)
@@ -87,13 +93,10 @@ class KNXExposeSensor:
     @callback
     def async_register(self, config: ConfigType) -> ExposeSensor:
         """Register listener."""
-        if self.expose_attribute is not None:
+        name = f"{self.entity_id}__{self.expose_attribute or "state"}"
-            _name = self.entity_id + "__" + self.expose_attribute
-        else:
-            _name = self.entity_id
         device = ExposeSensor(
             xknx=self.xknx,
-            name=_name,
+            name=name,
             group_address=config[KNX_ADDRESS],
             respond_to_read=config[CONF_RESPOND_TO_READ],
             value_type=self.expose_type,
@@ -132,24 +135,33 @@ class KNXExposeSensor:
         else:
             value = state.state
 
+        if self.value_template is not None:
+            try:
+                value = self.value_template.async_render_with_possible_json_value(
+                    value, error_value=None
+                )
+            except (TemplateError, TypeError, ValueError) as err:
+                _LOGGER.warning(
+                    "Error rendering value template for KNX expose %s %s: %s",
+                    self.device.name,
+                    self.value_template.template,
+                    err,
+                )
+                return None
+
         if self.expose_type == "binary":
             if value in (1, STATE_ON, "True"):
                 return True
             if value in (0, STATE_OFF, "False"):
                 return False
-        if (
+        if value is not None and (
-            value is not None
+            isinstance(self.device.sensor_value, RemoteValueSensor)
-            and isinstance(self.device.sensor_value, RemoteValueSensor)
-            and issubclass(self.device.sensor_value.dpt_class, DPTNumeric)
         ):
-            return float(value)
+            if issubclass(self.device.sensor_value.dpt_class, DPTNumeric):
-        if (
+                return float(value)
-            value is not None
+            if issubclass(self.device.sensor_value.dpt_class, DPTString):
-            and isinstance(self.device.sensor_value, RemoteValueSensor)
+                # DPT 16.000 only allows up to 14 Bytes
-            and issubclass(self.device.sensor_value.dpt_class, DPTString)
+                return str(value)[:14]
-        ):
-            # DPT 16.000 only allows up to 14 Bytes
-            return str(value)[:14]
         return value
 
     async def _async_entity_changed(self, event: Event[EventStateChangedData]) -> None:

homeassistant/components/knx/schema.py

@@ -37,6 +37,7 @@ from homeassistant.const import (
     CONF_NAME,
     CONF_PAYLOAD,
     CONF_TYPE,
+    CONF_VALUE_TEMPLATE,
     Platform,
 )
 import homeassistant.helpers.config_validation as cv
@@ -559,6 +560,7 @@ class ExposeSchema(KNXPlatformSchema):
             vol.Required(CONF_ENTITY_ID): cv.entity_id,
             vol.Optional(CONF_KNX_EXPOSE_ATTRIBUTE): cv.string,
             vol.Optional(CONF_KNX_EXPOSE_DEFAULT): cv.match_all,
+            vol.Optional(CONF_VALUE_TEMPLATE): cv.template,
         }
     )
     ENTITY_SCHEMA = vol.Any(EXPOSE_SENSOR_SCHEMA, EXPOSE_TIME_SCHEMA)

tests/components/knx/test_expose.py

@@ -8,7 +8,12 @@ import pytest
 
 from homeassistant.components.knx import CONF_KNX_EXPOSE, DOMAIN, KNX_ADDRESS
 from homeassistant.components.knx.schema import ExposeSchema
-from homeassistant.const import CONF_ATTRIBUTE, CONF_ENTITY_ID, CONF_TYPE
+from homeassistant.const import (
+    CONF_ATTRIBUTE,
+    CONF_ENTITY_ID,
+    CONF_TYPE,
+    CONF_VALUE_TEMPLATE,
+)
 from homeassistant.core import HomeAssistant
 from homeassistant.util import dt as dt_util
 
@@ -237,6 +242,54 @@ async def test_expose_cooldown(hass: HomeAssistant, knx: KNXTestKit) -> None:
     await knx.assert_write("1/1/8", (3,))
 
 
+async def test_expose_value_template(
+    hass: HomeAssistant, knx: KNXTestKit, caplog: pytest.LogCaptureFixture
+) -> None:
+    """Test an expose with value_template."""
+    entity_id = "fake.entity"
+    attribute = "brightness"
+    binary_address = "1/1/1"
+    percent_address = "2/2/2"
+    await knx.setup_integration(
+        {
+            CONF_KNX_EXPOSE: [
+                {
+                    CONF_TYPE: "binary",
+                    KNX_ADDRESS: binary_address,
+                    CONF_ENTITY_ID: entity_id,
+                    CONF_VALUE_TEMPLATE: "{{ not value == 'on' }}",
+                },
+                {
+                    CONF_TYPE: "percentU8",
+                    KNX_ADDRESS: percent_address,
+                    CONF_ENTITY_ID: entity_id,
+                    CONF_ATTRIBUTE: attribute,
+                    CONF_VALUE_TEMPLATE: "{{ 255 - value }}",
+                },
+            ]
+        },
+    )
+
+    # Change attribute to 0
+    hass.states.async_set(entity_id, "on", {attribute: 0})
+    await hass.async_block_till_done()
+    await knx.assert_write(binary_address, False)
+    await knx.assert_write(percent_address, (255,))
+
+    # Change attribute to 255
+    hass.states.async_set(entity_id, "off", {attribute: 255})
+    await hass.async_block_till_done()
+    await knx.assert_write(binary_address, True)
+    await knx.assert_write(percent_address, (0,))
+
+    # Change attribute to null (eg. light brightness)
+    hass.states.async_set(entity_id, "off", {attribute: None})
+    await hass.async_block_till_done()
+    # without explicit `None`-handling or default value this fails with
+    # TypeError: unsupported operand type(s) for -: 'int' and 'NoneType'
+    assert "Error rendering value template for KNX expose" in caplog.text
+
+
 async def test_expose_conversion_exception(
     hass: HomeAssistant, caplog: pytest.LogCaptureFixture, knx: KNXTestKit
 ) -> None: