Fix aggregated values for None samples

If the samples in the protobuf of the aggregated response has the value
not set (e.g. when the service sends None values), the generated python
code falls back to zeroes when the field is accessed. This case needs to
be handled explicitly by the client, which now sets these values to NaN.

Signed-off-by: cwasicki <[email protected]>

Author: cwasicki

src/frequenz/client/reporting/_types.py

@@ -3,6 +3,7 @@
 
 """Types for the Reporting API client."""
 
+import math
 from collections.abc import Iterable, Iterator
 from dataclasses import dataclass
 from datetime import datetime
@@ -180,10 +181,25 @@ class AggregatedMetric:
 
     def sample(self) -> MetricSample:
         """Return the aggregated metric sample."""
-        return MetricSample(
-            timestamp=datetime_from_proto(self._data_pb.sample.sample_time),
-            microgrid_id=self._data_pb.aggregation_config.microgrid_id,
-            component_id=self._data_pb.aggregation_config.aggregation_formula,
-            metric=Metric(self._data_pb.aggregation_config.metric).name,
-            value=self._data_pb.sample.sample.value,
+        config = self._data_pb.aggregation_config
+        sample = self._data_pb.sample
+
+        timestamp = datetime_from_proto(sample.sample_time)
+        microgrid_id = config.microgrid_id
+        component_id = config.aggregation_formula
+        metric = Metric(config.metric).name
+        # Ignoring this verification results in
+        # values of zero if the field is not set.
+        if sample.HasField("sample") and sample.sample.HasField("value"):
+            value = sample.sample.value
+        else:
+            value = math.nan
+
+        ret = MetricSample(
+            timestamp=timestamp,
+            microgrid_id=microgrid_id,
+            component_id=component_id,
+            metric=metric,
+            value=value,
         )
+        return ret