Backport PR #1792: Fix/support compatible units in time series specs (#1792)

* feat: add doctest to VariableQuantityField._get_unit

Signed-off-by: F.N. Claessen <felix@seita.nl>

* fix: allow convertible units in time series specs

Signed-off-by: F.N. Claessen <felix@seita.nl>

* docs: touch up some previous changelog entries under v0.29.1

Signed-off-by: F.N. Claessen <felix@seita.nl>

* docs: changelog entry

Signed-off-by: F.N. Claessen <felix@seita.nl>

* docs: update month for v0.29.1

Signed-off-by: F.N. Claessen <felix@seita.nl>

* fix: do not allow mixing kW and kWh units within a single time series specification

Signed-off-by: F.N. Claessen <felix@seita.nl>

---------

Signed-off-by: F.N. Claessen <felix@seita.nl>

(cherry picked from commit 8ce07b4)
Signed-off-by: F.N. Claessen <felix@seita.nl>

Author: Flix6x

documentation/changelog.rst

@@ -4,11 +4,12 @@ FlexMeasures Changelog
 **********************
 
 
-v0.29.1 | October XX, 2025
+v0.29.1 | November 5, 2025
 ============================
 
 Bugfixes
 -----------
+* Support different but still compatible units in time series segments of variable quantities [see `PR #1792 <https://www.github.com/FlexMeasures/flexmeasures/pull/1792>`_]
 * Fix account and `/assets/owned_by` pages rendering, giving them asset icons [see `PR #1772 <https://github.com/FlexMeasures/flexmeasures/pull/1772>`_]
 * Allow consultants to view client users [see `PR #1755 <https://www.github.com/FlexMeasures/flexmeasures/pull/1755>`_]
 * Fix bug where removed flex-model fields don't show up under the dropdown for new fields, except after a page refresh [see `PR #1775 <https://www.github.com/FlexMeasures/flexmeasures/pull/1775>`_]

flexmeasures/data/schemas/sensors.py

@@ -431,13 +431,23 @@ def _get_original_unit(
         return unit
 
     def _get_unit(self, variable_quantity: ur.Quantity | list[dict] | Sensor) -> str:
-        """Obtain the unit from the (deserialized) variable quantity."""
+        """Obtain the unit from the (deserialized) variable quantity.
+
+        >>> VariableQuantityField("MW")._get_unit(ur.Quantity("3 kWh"))
+        'kWh'
+        >>> VariableQuantityField("/MW")._get_unit([{'value': ur.Quantity("3 kEUR/MWh")}, {'value': ur.Quantity("0 EUR/kWh")}])
+        'kEUR/MWh'
+        """
         if isinstance(variable_quantity, ur.Quantity):
             unit = str(variable_quantity.units)
         elif isinstance(variable_quantity, list):
             unit = str(variable_quantity[0]["value"].units)
             if not all(
-                str(variable_quantity[j]["value"].units) == unit
+                units_are_convertible(
+                    from_unit=str(variable_quantity[j]["value"].units),
+                    to_unit=unit,
+                    duration_known=False,  # prevent mistakes by not allowing to mix kW and kWh units within a single time series specification
+                )
                 for j in range(len(variable_quantity))
             ):
                 raise ValidationError(