Fix Measurement.to_xml() writing invalid LuminousIntensity on FilterM…

CHANGELOG.md

@@ -164,7 +164,6 @@ having to use the .utils package. See more details below.
 
 ```python
 modes_info = gdtf_fixture.dmx_modes.as_dict()
-
 ```
 
 ##### .utils.get\_geometry\_by\_name
@@ -176,7 +175,7 @@ gdtf_fixture.geometries.get_geometry_by_name("geometry name")
 ##### .utils.get\_geometry\_by\_type
 
 ```python
-#this is a static method and requires a root_geometry
+# this is a static method and requires a root_geometry
 gdtf_fixture.geometries.get_geometry_by_type(geometry_root, geometry_type)
 ```
 

pygdtf/__init__.py

@@ -1003,7 +1003,9 @@ def to_xml(self):
         attrs = {}
         if self.physical is not None:
             attrs["Physical"] = f"{self.physical:.6f}"
-        if self.luminous_intensity is not None:
+        if self.luminous_intensity is not None and (
+            "LuminousIntensity" in self._attr_keys or self.luminous_intensity != 0
+        ):
             attrs["LuminousIntensity"] = f"{self.luminous_intensity:.6f}"
         if self.transmission is not None and (
             "Transmission" in self._attr_keys or self.transmission != 0

tests/test_filter_measurement.py

@@ -0,0 +1,114 @@
+# MIT License
+#
+# Copyright (C) 2026 Marvin
+#
+# This file is part of pygdtf.
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+from pathlib import Path
+from xml.etree import ElementTree
+
+import pygdtf
+
+# A FilterMeasurement never carries LuminousIntensity in valid GDTF (gdtf.xsd:
+# FilterMeasurement declares Physical, Transmission and InterpolationTo only -
+# LuminousIntensity is not a permitted attribute there, unlike on
+# EmitterMeasurement where it is required). Round-tripping a fixture whose
+# Filter/Measurement never had LuminousIntensity must not invent one.
+_DSC_XML = """<?xml version="1.0" encoding="UTF-8"?>
+<GDTF DataVersion="1.2">
+  <FixtureType Name="Test" ShortName="Test" LongName="Test" Manufacturer="Test"
+    Description="Test" FixtureTypeID="00000000-0000-0000-0000-000000000000"
+    Thumbnail="" ThumbnailOffsetX="0" ThumbnailOffsetY="0" RefFT="" CanHaveChildren="No">
+    <AttributeDefinitions>
+      <ActivationGroups/>
+      <FeatureGroups>
+        <FeatureGroup Name="Dimmer" Pretty="Dimmer">
+          <Feature Name="Dimmer"/>
+        </FeatureGroup>
+      </FeatureGroups>
+      <Attributes>
+        <Attribute Name="Dimmer" Pretty="Dim" Feature="Dimmer.Dimmer" PhysicalUnit="None"/>
+      </Attributes>
+    </AttributeDefinitions>
+    <Wheels/>
+    <PhysicalDescriptions>
+      <ColorSpace Mode="sRGB"/>
+      <AdditionalColorSpaces/>
+      <Gamuts/>
+      <Filters>
+        <Filter Name="ND Filter">
+          <Measurement Physical="0.000000" Transmission="80.000000"/>
+        </Filter>
+      </Filters>
+      <Emitters>
+        <Emitter Name="LED White">
+          <Measurement Physical="0.000000" LuminousIntensity="50.000000"/>
+        </Emitter>
+      </Emitters>
+      <DMXProfiles/>
+      <CRIs/>
+      <Connectors/>
+      <Properties/>
+    </PhysicalDescriptions>
+    <Models>
+      <Model Name="Base" PrimitiveType="Cube"/>
+    </Models>
+    <Geometries>
+      <Geometry Name="Base" Model="Base"/>
+    </Geometries>
+    <DMXModes>
+      <DMXMode Name="Default" Geometry="Base">
+        <DMXChannels>
+          <DMXChannel Offset="1" Geometry="Base">
+            <LogicalChannel Attribute="Dimmer">
+              <ChannelFunction Name="Dimmer" Attribute="Dimmer" Default="0/1"/>
+            </LogicalChannel>
+          </DMXChannel>
+        </DMXChannels>
+      </DMXMode>
+    </DMXModes>
+  </FixtureType>
+</GDTF>
+"""
+
+
+def test_filter_measurement_roundtrip_omits_luminous_intensity(tmp_path: Path):
+    dsc_file = tmp_path / "description.xml"
+    dsc_file.write_text(_DSC_XML, encoding="utf-8")
+
+    with pygdtf.FixtureType(dsc_file=str(dsc_file)) as fixture:
+        writer = pygdtf.FixtureTypeWriter(fixture)
+        output = tmp_path / "roundtrip.xml"
+        writer.write_gdtf(output)
+
+    root = ElementTree.fromstring(output.read_bytes())
+
+    filter_measurement = root.find(
+        "./FixtureType/PhysicalDescriptions/Filters/Filter/Measurement"
+    )
+    assert filter_measurement is not None
+    assert "LuminousIntensity" not in filter_measurement.attrib
+
+    emitter_measurement = root.find(
+        "./FixtureType/PhysicalDescriptions/Emitters/Emitter/Measurement"
+    )
+    assert emitter_measurement is not None
+    assert emitter_measurement.attrib.get("LuminousIntensity") == "50.000000"