Correct how unit used for statistics is determined (#79725)

homeassistant/components/sensor/recorder.py

@@ -149,13 +149,20 @@ def _normalize_states(
 
     state_unit = fstates[0][1].attributes.get(ATTR_UNIT_OF_MEASUREMENT)
 
-    if state_unit not in statistics.STATISTIC_UNIT_TO_UNIT_CONVERTER or (
+    statistics_unit: str | None
-        old_metadata
+    if not old_metadata:
-        and old_metadata["unit_of_measurement"]
+        # We've not seen this sensor before, the first valid state determines the unit
-        not in statistics.STATISTIC_UNIT_TO_UNIT_CONVERTER
+        # used for statistics
+        statistics_unit = state_unit
+    else:
+        # We have seen this sensor before, use the unit from metadata
+        statistics_unit = old_metadata["unit_of_measurement"]
+
+    if (
+        not statistics_unit
+        or statistics_unit not in statistics.STATISTIC_UNIT_TO_UNIT_CONVERTER
     ):
-        # We're either not normalizing this device class or this entity is not stored
+        # The unit used by this sensor doesn't support unit conversion
-        # in a unit which can be converted, return the states as they are
 
         all_units = _get_units(fstates)
         if len(all_units) > 1:
@@ -182,13 +189,9 @@ def _normalize_states(
         state_unit = fstates[0][1].attributes.get(ATTR_UNIT_OF_MEASUREMENT)
         return state_unit, state_unit, fstates
 
-    converter = statistics.STATISTIC_UNIT_TO_UNIT_CONVERTER[state_unit]
+    converter = statistics.STATISTIC_UNIT_TO_UNIT_CONVERTER[statistics_unit]
     valid_fstates: list[tuple[float, State]] = []
 
-    statistics_unit: str | None = None
-    if old_metadata:
-        statistics_unit = old_metadata["unit_of_measurement"]
-
     for fstate, state in fstates:
         state_unit = state.attributes.get(ATTR_UNIT_OF_MEASUREMENT)
         # Exclude states with unsupported unit from statistics
@@ -198,14 +201,18 @@ def _normalize_states(
             if entity_id not in hass.data[WARN_UNSUPPORTED_UNIT]:
                 hass.data[WARN_UNSUPPORTED_UNIT].add(entity_id)
                 _LOGGER.warning(
-                    "%s has unit %s which can't be converted to %s",
+                    "The unit of %s (%s) can not be converted to the unit of previously "
+                    "compiled statistics (%s). Generation of long term statistics "
+                    "will be suppressed unless the unit changes back to %s or a "
+                    "compatible unit. "
+                    "Go to %s to fix this",
                     entity_id,
                     state_unit,
                     statistics_unit,
+                    statistics_unit,
+                    LINK_DEV_STATISTICS,
                 )
             continue
-        if statistics_unit is None:
-            statistics_unit = state_unit
 
         valid_fstates.append(
             (

tests/components/sensor/test_recorder.py

@@ -1900,12 +1900,13 @@ def test_list_statistic_ids_unsupported(hass_recorder, caplog, _attributes):
 
 
 @pytest.mark.parametrize(
-    "device_class, state_unit, display_unit, statistics_unit, unit_class, mean, min, max",
+    "device_class, state_unit, state_unit2, unit_class, mean, min, max",
     [
-        (None, None, None, None, None, 13.050847, -10, 30),
+        (None, None, "cats", None, 13.050847, -10, 30),
-        (None, "%", "%", "%", None, 13.050847, -10, 30),
+        (None, "%", "cats", None, 13.050847, -10, 30),
-        ("battery", "%", "%", "%", None, 13.050847, -10, 30),
+        ("battery", "%", "cats", None, 13.050847, -10, 30),
-        ("battery", None, None, None, None, 13.050847, -10, 30),
+        ("battery", None, "cats", None, 13.050847, -10, 30),
+        (None, "kW", "Wh", "power", 13.050847, -10, 30),
     ],
 )
 def test_compile_hourly_statistics_changing_units_1(
@@ -1913,8 +1914,7 @@ def test_compile_hourly_statistics_changing_units_1(
     caplog,
     device_class,
     state_unit,
-    display_unit,
+    state_unit2,
-    statistics_unit,
     unit_class,
     mean,
     min,
@@ -1931,7 +1931,7 @@ def test_compile_hourly_statistics_changing_units_1(
         "unit_of_measurement": state_unit,
     }
     four, states = record_states(hass, zero, "sensor.test1", attributes)
-    attributes["unit_of_measurement"] = "cats"
+    attributes["unit_of_measurement"] = state_unit2
     four, _states = record_states(
         hass, zero + timedelta(minutes=5), "sensor.test1", attributes
     )
@@ -1954,7 +1954,7 @@ def test_compile_hourly_statistics_changing_units_1(
             "has_sum": False,
             "name": None,
             "source": "recorder",
-            "statistics_unit_of_measurement": statistics_unit,
+            "statistics_unit_of_measurement": state_unit,
             "unit_class": unit_class,
         },
     ]
@@ -1978,8 +1978,8 @@ def test_compile_hourly_statistics_changing_units_1(
     do_adhoc_statistics(hass, start=zero + timedelta(minutes=10))
     wait_recording_done(hass)
     assert (
-        "The unit of sensor.test1 (cats) can not be converted to the unit of "
+        f"The unit of sensor.test1 ({state_unit2}) can not be converted to the unit of "
-        f"previously compiled statistics ({display_unit})" in caplog.text
+        f"previously compiled statistics ({state_unit})" in caplog.text
     )
     statistic_ids = list_statistic_ids(hass)
     assert statistic_ids == [
@@ -1989,7 +1989,7 @@ def test_compile_hourly_statistics_changing_units_1(
             "has_sum": False,
             "name": None,
             "source": "recorder",
-            "statistics_unit_of_measurement": statistics_unit,
+            "statistics_unit_of_measurement": state_unit,
             "unit_class": unit_class,
         },
     ]