Fix KNX Expose for strings longer than 14 bytes (#63026)

* Fix KNX Expose for too long strings

* Fix tests

* Catch exception and avoid error during config entry setup for exposures

* Properly catch exceptions in knx expose

* Fix pylint

* Fix CI

* Add test for conversion error

homeassistant/components/knx/expose.py

@@ -2,10 +2,12 @@
 from __future__ import annotations
 
 from collections.abc import Callable
+import logging
 
 from xknx import XKNX
 from xknx.devices import DateTime, ExposeSensor
-from xknx.dpt import DPTNumeric
+from xknx.dpt import DPTNumeric, DPTString
+from xknx.exceptions import ConversionError
 from xknx.remote_value import RemoteValueSensor
 
 from homeassistant.const import (
@@ -22,6 +24,8 @@
 from .const import KNX_ADDRESS
 from .schema import ExposeSchema
 
+_LOGGER = logging.getLogger(__name__)
+
 
 @callback
 def create_knx_exposure(
@@ -101,7 +105,10 @@ def _init_expose_state(self) -> None:
         """Initialize state of the exposure."""
         init_state = self.hass.states.get(self.entity_id)
         state_value = self._get_expose_value(init_state)
-        self.device.sensor_value.value = state_value
+        try:
+            self.device.sensor_value.value = state_value
+        except ConversionError:
+            _LOGGER.exception("Error during sending of expose sensor value")
 
     @callback
     def shutdown(self) -> None:
@@ -132,6 +139,13 @@ def _get_expose_value(self, state: State | None) -> StateType:
             and issubclass(self.device.sensor_value.dpt_class, DPTNumeric)
         ):
             return float(value)
+        if (
+            value is not None
+            and isinstance(self.device.sensor_value, RemoteValueSensor)
+            and issubclass(self.device.sensor_value.dpt_class, DPTString)
+        ):
+            # DPT 16.000 only allows up to 14 Bytes
+            return str(value)[:14]
         return value
 
     async def _async_entity_changed(self, event: Event) -> None:
@@ -148,7 +162,10 @@ async def _async_entity_changed(self, event: Event) -> None:
 
     async def _async_set_knx_value(self, value: StateType) -> None:
         """Set new value on xknx ExposeSensor."""
-        await self.device.set(value)
+        try:
+            await self.device.set(value)
+        except ConversionError:
+            _LOGGER.exception("Error during sending of expose sensor value")
 
 
 class KNXExposeTime:

tests/components/knx/test_expose.py

@@ -128,6 +128,73 @@ async def test_expose_attribute_with_default(hass: HomeAssistant, knx: KNXTestKi
     await knx.assert_write("1/1/8", (0,))
 
 
+async def test_expose_string(hass: HomeAssistant, knx: KNXTestKit):
+    """Test an expose to send string values of up to 14 bytes only."""
+
+    entity_id = "fake.entity"
+    attribute = "fake_attribute"
+    await knx.setup_integration(
+        {
+            CONF_KNX_EXPOSE: {
+                CONF_TYPE: "string",
+                KNX_ADDRESS: "1/1/8",
+                CONF_ENTITY_ID: entity_id,
+                CONF_ATTRIBUTE: attribute,
+                ExposeSchema.CONF_KNX_EXPOSE_DEFAULT: "Test",
+            }
+        },
+    )
+    assert not hass.states.async_all()
+
+    # Before init default value shall be sent as response
+    await knx.receive_read("1/1/8")
+    await knx.assert_response(
+        "1/1/8", (84, 101, 115, 116, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
+    )
+
+    # Change attribute; keep state
+    hass.states.async_set(
+        entity_id,
+        "on",
+        {attribute: "This is a very long string that is larger than 14 bytes"},
+    )
+    await knx.assert_write(
+        "1/1/8", (84, 104, 105, 115, 32, 105, 115, 32, 97, 32, 118, 101, 114, 121)
+    )
+
+
+async def test_expose_conversion_exception(hass: HomeAssistant, knx: KNXTestKit):
+    """Test expose throws exception."""
+
+    entity_id = "fake.entity"
+    attribute = "fake_attribute"
+    await knx.setup_integration(
+        {
+            CONF_KNX_EXPOSE: {
+                CONF_TYPE: "percent",
+                KNX_ADDRESS: "1/1/8",
+                CONF_ENTITY_ID: entity_id,
+                CONF_ATTRIBUTE: attribute,
+                ExposeSchema.CONF_KNX_EXPOSE_DEFAULT: 1,
+            }
+        },
+    )
+    assert not hass.states.async_all()
+
+    # Before init default value shall be sent as response
+    await knx.receive_read("1/1/8")
+    await knx.assert_response("1/1/8", (3,))
+
+    # Change attribute: Expect no exception
+    hass.states.async_set(
+        entity_id,
+        "on",
+        {attribute: 101},
+    )
+
+    await knx.assert_no_telegram()
+
+
 @patch("time.localtime")
 async def test_expose_with_date(localtime, hass: HomeAssistant, knx: KNXTestKit):
     """Test an expose with a date."""
@@ -138,7 +205,7 @@ async def test_expose_with_date(localtime, hass: HomeAssistant, knx: KNXTestKit)
                 CONF_TYPE: "datetime",
                 KNX_ADDRESS: "1/1/8",
             }
-        },
+        }
     )
     assert not hass.states.async_all()