Merge bb7bdd4 into 726cd32

flexmeasures/data/models/time_series.py

@@ -10,6 +10,7 @@
 from sqlalchemy.ext.mutable import MutableDict
 from sqlalchemy.orm import Query, Session
 from sqlalchemy.schema import UniqueConstraint
+from sqlalchemy import inspect
 import timely_beliefs as tb
 from timely_beliefs.beliefs.probabilistic_utils import get_median_belief
 import timely_beliefs.utils as tb_utils
@@ -584,6 +585,14 @@ def __init__(
         source: tb.DBBeliefSource,
         **kwargs,
     ):
+        # get a Sensor instance attached to the database session (input sensor is detached)
+        # check out Issue #683 for more details
+        inspection_obj = inspect(sensor, raiseerr=False)
+        if inspection_obj:
+            # fetch Sensor only when it is detached
+            if inspection_obj.detached:
+                sensor = Sensor.query.get(sensor.id)
+
         tb.TimedBeliefDBMixin.__init__(self, sensor, source, **kwargs)
         tb_utils.remove_class_init_kwargs(tb.TimedBeliefDBMixin, kwargs)
         db.Model.__init__(self, **kwargs)