Do not resample data of sensors recording instantaneous values

documentation/changelog.rst

@@ -23,7 +23,7 @@ v0.11.1 | September XX, 2022
 
 Bugfixes
 -----------
-
+* Do not fail asset page if one of the shown sensors records instantaneous values [see `PR #491 <http://www.github.com/FlexMeasures/flexmeasures/pull/491>`_]
 
 
 v0.11.0 | August 28, 2022

flexmeasures/data/models/charts/belief_charts.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from datetime import datetime
+from datetime import datetime, timedelta
 
 from flexmeasures.data.models.charts.defaults import FIELD_DEFINITIONS
 from flexmeasures.utils.flexmeasures_inflection import capitalize
@@ -72,8 +72,13 @@ def chart_for_multiple_sensors(
     **override_chart_specs: dict,
 ):
     sensors_specs = []
-    min_resolution_in_ms = (
-        min(sensor.event_resolution for sensor in sensors).total_seconds() * 1000
+    minimum_non_zero_resolution_in_ms = (
+        min(
+            sensor.event_resolution
+            for sensor in sensors
+            if sensor.event_resolution > timedelta(0)
+        ).total_seconds()
+        * 1000
     )
     for sensor in sensors:
         unit = sensor.unit if sensor.unit else "a.u."
@@ -112,7 +117,9 @@ def chart_for_multiple_sensors(
                 {
                     "mark": {
                         "type": "line",
-                        "interpolate": "step-after",
+                        "interpolate": "step-after"
+                        if sensor.event_resolution != timedelta(0)
+                        else "linear",
                         "clip": True,
                     },
                     "encoding": {
@@ -143,7 +150,7 @@ def chart_for_multiple_sensors(
                     },
                     "transform": [
                         {
-                            "calculate": f"datum.event_start + {min_resolution_in_ms}",
+                            "calculate": f"datum.event_start + {minimum_non_zero_resolution_in_ms}",
                             "as": "event_end",
                         },
                     ],

flexmeasures/data/models/generic_assets.py

@@ -381,10 +381,15 @@ def search_beliefs(
             from flexmeasures.data.services.time_series import simplify_index
 
             if sensors:
-                min_resolution = min(bdf.event_resolution for bdf in bdf_dict.values())
+                minimum_non_zero_resolution = min(
+                    bdf.event_resolution
+                    for bdf in bdf_dict.values()
+                    if bdf.event_resolution > timedelta(0)
+                )
                 df_dict = {}
                 for sensor, bdf in bdf_dict.items():
-                    bdf = bdf.resample_events(min_resolution)
+                    if bdf.event_resolution > timedelta(0):
+                        bdf = bdf.resample_events(minimum_non_zero_resolution)
                     df = simplify_index(
                         bdf, index_levels_to_columns=["source"]
                     ).set_index(["source"], append=True)