fixed unit handling for the metadata provisioning

README.md

 [![Build](https://git-ce.rwth-aachen.de/wzl-mq-ms/forschung-lehre/lava/unified-device-interface/python/badges/master/pipeline.svg)](https://git-ce.rwth-aachen.de/wzl-mq-ms/forschung-lehre/lava/unified-device-interface/python/commits/master)
 
 # Python Unified Device Interface
-Current stable version: 10.0.6
+Current stable version: 10.0.7
 
 ## Installation
 1. Install the WZL-UDI package via pip
@@ -69,6 +69,9 @@ Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)
 
 ## Recent changes
 
+**10.0.7** - 2024-03-22
+  - fixed unit handling for the metadata provisioning
+
 **10.0.6** - 2024-03-22
   - fixed validation of rfc3339 datetime strings
 

setup.py

@@ -4,7 +4,7 @@ with open("README.md", "r", encoding="utf-8") as fh:
     long_description = fh.read()
 
 setup(name='wzl-udi',
-      version='10.0.6',
+      version='10.0.7',
       url='https://git-ce.rwth-aachen.de/wzl-mq-public/soil/python',
       project_urls={
           "Bug Tracker": "https://git-ce.rwth-aachen.de/wzl-mq-public/soil/python/-/issues",

src/soil/measurement.py

@@ -238,10 +238,11 @@ class Measurement(Variable):
 
             # create result node
             unit_triples = list(self._metadata.triples((None, Namespaces.qudt.applicableUnit, None)))
-            assert len(unit_triples) == 1
+            assert self.datatype in [Datatype.STRING, Datatype.ENUM, Datatype.BOOLEAN, Datatype.TIME] or len(unit_triples) == 1
 
             data_graph.add((result_subject, Namespaces.rdf.type, rdflib.URIRef(Namespaces.sosa.Result)))
             data_graph.add((result_subject, Namespaces.sosa.isResultOf, measurement_subject))
+            if len(unit_triples) == 1:
                 data_graph.add((result_subject, Namespaces.qudt.unit, unit_triples[0][2]))
             data_graph.add((result_subject, Namespaces.schema.license, Semantics.data_license))