#755 FIX unit component duplication BUG

src/csvcubed/writers/helpers/qbwriter/dsdtordfmodelshelper.py

@@ -301,17 +301,29 @@ def _get_qb_component_specs_for_col(
                 self._get_qb_attribute_specification(column_name_uri_safe, component)
             ]
         elif isinstance(component, QbMultiUnits):
-            return [self._get_qb_units_column_specification(column_name_uri_safe)]
+            return self._get_qb_units_column_specification(column_name_uri_safe)
         elif isinstance(component, QbMultiMeasureDimension):
             return self._get_qb_measure_dimension_specifications(component)
         elif isinstance(component, QbObservationValue):
             return self._get_qb_obs_val_specifications(component)
         else:
             raise TypeError(f"Unhandled component type {type(component)}")
 
+    _units_component_already_defined: bool = False
+    """
+    Records whether or not a units component has already been defined in this cube.
+    If it has, don't define it again.
+    """
+
     def _get_qb_units_column_specification(
         self, column_name_uri_safe: str
-    ) -> rdf.qb.AttributeComponentSpecification:
+    ) -> List[rdf.qb.AttributeComponentSpecification]:
+        if self._units_component_already_defined:
+            # Don't define a second units component, the first one will work just fine.
+            return []
+
+        self._units_component_already_defined = True
+
         component = rdf.qb.AttributeComponentSpecification(
             self._uris.get_component_uri(column_name_uri_safe)
         )
@@ -326,7 +338,7 @@ def _get_qb_units_column_specification(
             component.uri,
         )
 
-        return component
+        return [component]
 
     def _get_qb_obs_val_specifications(
         self, observation_value: QbObservationValue
@@ -339,7 +351,7 @@ def _get_qb_obs_val_specifications(
 
         unit = observation_value.unit
         if unit is not None:
-            specs.append(self._get_qb_units_column_specification("unit"))
+            specs += self._get_qb_units_column_specification("unit")
 
         if observation_value.is_pivoted_shape_observation:
             assert observation_value.measure is not None

tests/unit/writers/qbwriter/test_dsdtordfmodelshelper.py

@@ -1,6 +1,7 @@
 import pandas as pd
 import pytest
 from csvcubedmodels import rdf
+from csvcubedmodels.rdf import qb
 from rdflib import RDFS, Graph, Literal, URIRef
 
 from csvcubed.models.cube.cube import Cube
@@ -577,5 +578,69 @@ def test_qb_order_of_components():
     ) in graph
 
 
+def test_units_component_duplication():
+    """This test checks if there are multiple observation value columns with units, only one unit component will be generated.
+    link to the issue: https://github.com/GSS-Cogs/csvcubed/issues/755
+    """
+
+    data = pd.DataFrame(
+        {
+            "Existing Dimension": ["A", "B", "C"],
+            "Value": [1, 2, 3],
+            "Existing Attribute": ["Provisional", "Final", "Provisional"],
+        }
+    )
+
+    cube = Cube(
+        CatalogMetadata("Some Dataset"),
+        data,
+        [
+            QbColumn(
+                "Existing Dimension",
+                ExistingQbDimension(
+                    "https://example.org/dimensions/existing_dimension",
+                    arbitrary_rdf=[
+                        TripleFragment(RDFS.label, "Existing Dimension Component")
+                    ],
+                ),
+            ),
+            QbColumn(
+                "Value",
+                QbObservationValue(
+                    NewQbMeasure("Some Measure"), NewQbUnit("Some Unit")
+                ),
+            ),
+            QbColumn(
+                "Other Value",
+                QbObservationValue(
+                    NewQbMeasure("Some Other Measure"), NewQbUnit("Some Other Unit")
+                ),
+            ),
+        ],
+    )
+
+    dsd_helper = DsdToRdfModelsHelper(cube, UriHelper(cube))
+    dataset = dsd_helper._generate_qb_dataset_dsd_definitions()
+    graph = dataset.to_graph(Graph())
+
+    assert (
+        URIRef("some-dataset.csv#component/unit"),
+        rdf.QB.order,
+        Literal(3),
+    ) in graph
+
+    list_of_units = [
+        component
+        for component in dataset.structure.components
+        if (
+            isinstance(component, qb.AttributeComponentSpecification)
+            and str(component.attribute.uri)
+            == "http://purl.org/linked-data/sdmx/2009/attribute#unitMeasure"
+        )
+    ]
+
+    assert len(list_of_units) == 1
+
+
 if __name__ == "__main__":
     pytest.main()