Fallback for metadata of conda packages

src/scippneutron/metadata/_model.py

@@ -255,11 +255,9 @@ def from_package_metadata(cls, package_name: str) -> Software:
         :
             A Software instance.
         """
-        from importlib.metadata import version
-
         return cls(
             name=package_name,
-            version=version(package_name),
+            version=_deduce_package_version(package_name),
             url=_deduce_package_source_url(package_name),
             doi=None,
         )
@@ -277,10 +275,39 @@ def compact_repr(self) -> str:
         return self.name_version
 
 
+def _deduce_package_version(package_name: str) -> str | None:
+    from importlib.metadata import PackageNotFoundError, version
+
+    try:
+        return version(package_name)
+    except PackageNotFoundError:
+        # Either the package is not installed or has no metadata.
+        from importlib import import_module
+
+        try:
+            package = import_module(package_name)
+        except ModuleNotFoundError as e:
+            raise e from None
+
+        try:
+            return package.__version__
+        except AttributeError:
+            raise RuntimeError(
+                f"Package '{package_name}' has no metadata and no "
+                f"__version__ attribute. Specify the version manually."
+            ) from None
+
+
 def _deduce_package_source_url(package_name: str) -> str | None:
-    from importlib.metadata import metadata
+    from importlib.metadata import PackageNotFoundError, metadata
+
+    try:
+        meta = metadata(package_name)
+    except PackageNotFoundError:
+        # Either the package is not installed or has no metadata.
+        return None
 
-    if not (urls := metadata(package_name).get_all("project-url")):
+    if not (urls := meta.get_all("project-url")):
         return None
 
     try:

tests/metadata/metadata_model_test.py

@@ -2,6 +2,7 @@
 # Copyright (c) 2025 Scipp contributors (https://github.com/scipp)
 
 
+import pytest
 import scipp as sc
 import scippnexus as snx
 from dateutil.parser import parse as parse_datetime
@@ -44,10 +45,15 @@ def test_software_from_from_package_metadata_first_party() -> None:
 
 def test_software_from_from_package_metadata_third_party() -> None:
     software = metadata.Software.from_package_metadata('scipp')
-    expected = metadata.Software(
-        name='scipp',
-        version=sc.__version__,
-        url='https://github.com/scipp/scipp',
-        doi=None,  # Cannot be deduced
+    assert software.name == 'scipp'
+    assert software.version == sc.__version__
+    assert software.url in (
+        'https://github.com/scipp/scipp',  # properly deduced
+        None,  # fallback for our conda packages
     )
-    assert software == expected
+    assert software.doi is None
+
+
+def test_software_from_from_package_metadata_fails_when_package_not_installed() -> None:
+    with pytest.raises(ModuleNotFoundError):
+        metadata.Software.from_package_metadata('not-a-package')