Miscellaneous fixes for 2025-W44

doc/whatsnew.rst

@@ -9,6 +9,11 @@ Next release
 - Python 3.14 (`released 2025-10-07 <https://www.python.org/downloads/release/python-3140/>`_) is fully supported (:pull:`249`).
 - Python 3.9 support is dropped, as `it has reached end-of-life <https://peps.python.org/pep-0569/#lifespan>`__ (:pull:`249`).
   :mod:`sdmx` requires Python 3.10 or later.
+- :class:`.URN` parses letters in the version part of a URN (:issue:`230`, :pull:`252`).
+  This fixes a bug in v2.16.0–v2.23.1 where creating :class:`.VersionableArtefact`
+  with both :py:`version=...` and :py:`urn=...` would raise :class:`ValueError`
+  even if the two were in agreement.
+- Fix two regressions in :func:`.to_pandas` introduced in v2.23.0 (:issue:`251`, :pull:`252`).
 
 v2.23.1 (2025-10-01)
 ====================

sdmx/convert/pandas.py

@@ -503,6 +503,15 @@ def to_pandas(obj, **kwargs):
 
     `kwargs` can include any of the attributes of :class:`.PandasConverter`.
 
+    .. versionchanged:: 1.0
+
+       :func:`.to_pandas` handles all types of objects,
+       replacing the earlier, separate ``data2pandas`` and ``structure2pd`` writers.
+
+    .. versionchanged:: 2.23.0
+
+       :func:`.to_pandas` is a thin wrapper for :class:`.PandasConverter`.
+
     Other parameters
     ----------------
     format_options :
@@ -513,15 +522,6 @@ def to_pandas(obj, **kwargs):
     time_format :
         if given, the :attr:`.CSVFormatOptions.time_format` attribute of the
         `format_options` keyword argument is replaced.
-
-    .. versionchanged:: 1.0
-
-       :func:`.to_pandas` handles all types of objects,
-       replacing the earlier, separate ``data2pandas`` and ``structure2pd`` writers.
-
-    .. versionchanged:: 2.23.0
-
-       :func:`.to_pandas` is a thin wrapper for :class:`.PandasConverter`.
     """
     csv.common.kwargs_to_format_options(kwargs, csv.common.CSVFormatOptions)
     return PandasConverter(**kwargs).convert(obj)
@@ -685,6 +685,7 @@ def convert_dataset(c: "PandasConverter", obj: common.BaseDataSet):
         Otherwise.
     """
     c._context[common.BaseDataSet] = obj
+    c._context.setdefault(common.BaseDataStructureDefinition, obj.structured_by)
     c._columns = ColumnSpec(pc=c, ds=obj)
 
     # - Apply convert_obs() to every obs → iterable of list.
@@ -697,7 +698,11 @@ def convert_dataset(c: "PandasConverter", obj: common.BaseDataSet):
     # - (Possibly) convert certain columns to datetime.
     # - (Possibly) reshape.
     result = (
-        pd.DataFrame(map(c._columns.convert_obs, obj.obs))
+        pd.DataFrame(
+            map(c._columns.convert_obs, obj.obs)
+            if obj.obs
+            else [[None] * len(c._columns.obs)]
+        )
         .dropna(how="all")
         .set_axis(c._columns.obs, axis=1)  # NB This must come after DataFrame(map(…))
         .assign(**c._columns.assign)

sdmx/model/common.py

@@ -184,7 +184,7 @@ def value(self) -> str | None:
         return None
 
 
-@dataclass
+@dataclass(slots=True)
 class AnnotableArtefact(Comparable):
     #: :class:`Annotations <.Annotation>` of the object.
     #:
@@ -244,7 +244,7 @@ def eval_annotation(self, id: str, globals=None):
             return value
 
 
-@dataclass
+@dataclass(slots=True)
 class IdentifiableArtefact(AnnotableArtefact):
     #: Unique identifier of the object.
     id: str = MissingID
@@ -349,8 +349,8 @@ def __post_init__(self):
         super().__post_init__()
 
         if not self.version:
-            self.version = self._urn.version
-        elif isinstance(self.version, str) and self.version == "None":
+            self.version = self._urn.version or None
+        elif isinstance(self.version, str) and self.version in ("", "None"):
             self.version = None
         elif self.urn and self.version != self._urn.version:
             raise ValueError(
@@ -1756,7 +1756,7 @@ def __add__(self, other):
         if not isinstance(other, Key) and other is not None:
             raise NotImplementedError
         else:
-            result.values.update_fast(other.values)
+            result.values.update_fast(getattr(other, "values", []))
         return result
 
     def __radd__(self, other):

sdmx/model/v21.py

@@ -300,6 +300,8 @@ class Observation(common.BaseObservation):
 class DataSet(common.BaseDataSet):
     """SDMX 2.1 DataSet."""
 
+    structured_by: DataStructureDefinition | None = None
+
     #: Named ``attachedAttribute`` in the IM.
     attrib: DictLikeDescriptor[str, common.AttributeValue] = DictLikeDescriptor()
 

sdmx/model/v30.py

@@ -394,6 +394,8 @@ class Observation(common.BaseObservation):
 class DataSet(common.BaseDataSet):
     """SDMX 3.0 Data Set."""
 
+    structured_by: DataStructureDefinition | None = None
+
 
 class StructureSpecificDataSet(DataSet):
     """SDMX 3.0 StructureSpecificDataSet.

sdmx/reader/xml/common.py

@@ -5,21 +5,28 @@
 from collections.abc import Callable, Iterable, Iterator, Mapping, Sequence
 from importlib import import_module
 from itertools import chain, count
-from typing import TYPE_CHECKING, Any, ClassVar, cast
+from typing import TYPE_CHECKING, Any, ClassVar, TypeVar, cast
 
 from lxml import etree
 from lxml.etree import QName
 
 import sdmx.urn
 from sdmx import message
 from sdmx.exceptions import XMLParseError  # noqa: F401
-from sdmx.format import Version, list_media_types
+from sdmx.format import Version as FormatVersion
+from sdmx.format import list_media_types
 from sdmx.model import common
+from sdmx.model.version import Version
 from sdmx.reader.base import BaseReader
 
 if TYPE_CHECKING:
     import types
 
+    AA = TypeVar("AA", bound=common.AnnotableArtefact)
+    IA = TypeVar("IA", bound=common.IdentifiableArtefact)
+    NA = TypeVar("NA", bound=common.NameableArtefact)
+    MA = TypeVar("MA", bound=common.MaintainableArtefact)
+
 # Sentinel value for a missing Agency
 _NO_AGENCY = common.Agency()
 
@@ -50,7 +57,9 @@ class BaseReference:
         "version",
     )
 
-    def __init__(self, reader, elem, cls_hint=None):
+    def __init__(
+        self, reader: "XMLEventReader", elem, cls_hint: type | None = None
+    ) -> None:
         parent_tag = elem.tag
 
         info = self.info_from_element(elem)
@@ -93,7 +102,7 @@ def __init__(self, reader, elem, cls_hint=None):
     @abstractmethod
     def info_from_element(cls, elem) -> dict[str, Any]: ...
 
-    def __str__(self):
+    def __str__(self) -> str:
         # NB for debugging only
         return (  # pragma: no cover
             f"{self.cls.__name__}={self.agency.id}:{self.id}({self.version}) → "
@@ -108,7 +117,7 @@ class XMLEventReader(BaseReader):
     suffixes = [".xml"]
 
     #: SDMX-ML version handled by this reader.
-    xml_version: ClassVar[Version]
+    xml_version: ClassVar[FormatVersion]
 
     #: Reference to the module defining the format read.
     format: ClassVar["types.ModuleType"]
@@ -129,7 +138,9 @@ def __init_subclass__(cls: type["XMLEventReader"]):
         # Empty dictionary
         cls.parser = {}
 
-        name = {Version["2.1"]: "v21", Version["3.0.0"]: "v30"}[cls.xml_version]
+        name = {FormatVersion["2.1"]: "v21", FormatVersion["3.0.0"]: "v30"}[
+            cls.xml_version
+        ]
         cls.format = import_module(f"sdmx.format.xml.{name}")
         cls.model = import_module(f"sdmx.model.{name}")
         cls.media_types = list_media_types(base="xml", version=cls.xml_version)
@@ -306,7 +317,7 @@ def _dump(self):  # pragma: no cover
                 )
         print("\nIgnore:\n", self.ignore)
 
-    def push(self, stack_or_obj, obj=None):
+    def push(self, stack_or_obj, obj=None) -> None:
         """Push an object onto a stack."""
         if stack_or_obj is None:
             return
@@ -335,11 +346,11 @@ def push(self, stack_or_obj, obj=None):
 
         self.stack[s][id] = obj
 
-    def stash(self, *stacks, name: str = "_stash"):
+    def stash(self, *stacks, name: str = "_stash") -> None:
         """Temporarily hide all objects in the given `stacks`."""
         self.push(name, {s: self.stack.pop(s, dict()) for s in stacks})
 
-    def unstash(self, name: str = "_stash"):
+    def unstash(self, name: str = "_stash") -> None:
         """Restore the objects hidden by the last :meth:`stash` call to their stacks.
 
         Calls to :meth:`.stash` and :meth:`.unstash` should be matched 1-to-1; if the
@@ -361,7 +372,7 @@ def get_single(
         self,
         cls_or_name: type | str,
         id: str | None = None,
-        version: str | None = None,
+        version: str | Version | None = None,
         subclass: bool = False,
     ) -> Any | None:
         """Return a reference to an object while leaving it in its stack.
@@ -475,7 +486,9 @@ def resolve(self, ref):
                     return parent.get_hierarchical(ref.target_id)
                 raise  # pragma: no cover
 
-    def annotable(self, cls, elem, **kwargs):
+    AA = TypeVar("AA", bound=common.AnnotableArtefact)
+
+    def annotable(self, cls: type["AA"], elem, **kwargs) -> "AA":
         """Create a AnnotableArtefact of `cls` from `elem` and `kwargs`.
 
         Collects all parsed <com:Annotation>.
@@ -485,12 +498,12 @@ def annotable(self, cls, elem, **kwargs):
             kwargs["annotations"].extend(self.pop_all(self.model.Annotation))
         return cls(**kwargs)
 
-    def identifiable(self, cls, elem, **kwargs):
+    def identifiable(self, cls: type["IA"], elem, **kwargs) -> "IA":
         """Create a IdentifiableArtefact of `cls` from `elem` and `kwargs`."""
         setdefault_attrib(kwargs, elem, "id", "urn", "uri")
         return self.annotable(cls, elem, **kwargs)
 
-    def nameable(self, cls, elem, **kwargs):
+    def nameable(self, cls: type["NA"], elem, **kwargs) -> "NA":
         """Create a NameableArtefact of `cls` from `elem` and `kwargs`.
 
         Collects all parsed :class:`.InternationalString` localizations of <com:Name>
@@ -502,7 +515,7 @@ def nameable(self, cls, elem, **kwargs):
             add_localizations(obj.description, self.pop_all("Description"))
         return obj
 
-    def maintainable(self, cls, elem, **kwargs):
+    def maintainable(self, cls: type["MA"], elem, **kwargs) -> "MA":
         """Create or retrieve a MaintainableArtefact of `cls` from `elem` and `kwargs`.
 
         Following the SDMX-IM class hierarchy, :meth:`maintainable` calls
@@ -578,7 +591,7 @@ def maintainable(self, cls, elem, **kwargs):
         return obj
 
 
-def add_localizations(target: common.InternationalString, values: list) -> None:
+def add_localizations(target: common.InternationalString, values: Sequence) -> None:
     """Add localized strings from *values* to *target*."""
     target.localizations.update({locale: label for locale, label in values})
 

sdmx/reader/xml/v21.py

@@ -499,7 +499,7 @@ def _item_start(reader, elem):
 @possible_reference(unstash=True)
 def _item_end(reader: Reader, elem):
     cls = reader.class_for_tag(elem.tag)
-    item = reader.nameable(cls, elem)
+    item: "common.Item" = reader.nameable(cls, elem)
 
     # Hierarchy is stored in two ways
 
@@ -718,7 +718,7 @@ def _cl(reader: Reader, elem):
     assert dsd is not None
 
     # Determine the class
-    cls = reader.class_for_tag(elem.tag)
+    cls: type[common.ComponentList] = reader.class_for_tag(elem.tag)
 
     args = dict(
         # Retrieve the components
@@ -746,11 +746,8 @@ def _cl(reader: Reader, elem):
 
     cl = reader.identifiable(cls, elem, **args)
 
-    try:
-        # DimensionDescriptor only
+    if isinstance(cl, common.DimensionDescriptor):
         cl.assign_order()
-    except AttributeError:
-        pass
 
     # Assign to the DSD eagerly (instead of in _dsd_end()) for reference by next
     # ComponentList e.g. so that AttributeRelationship can reference the
@@ -1040,7 +1037,7 @@ def _ar(reader, elem):
 def _structure_start(reader: Reader, elem):
     # Get any external reference created earlier, or instantiate a new object
     cls = reader.class_for_tag(elem.tag)
-    obj = reader.maintainable(cls, elem)
+    obj: "common.Structure" = reader.maintainable(cls, elem)
 
     if obj not in reader.stack[cls]:
         # A new object was created
@@ -1541,9 +1538,7 @@ def _hc_end(reader: Reader, elem):
             level = common.Level(id=level_ref.id)
 
     # Create the HierarchicalCode
-    obj = reader.identifiable(
-        reader.class_for_tag(elem.tag), elem, code=code, level=level
-    )
+    obj = reader.identifiable(common.HierarchicalCode, elem, code=code, level=level)
 
     # Count children represented as XML sub-elements of the parent
     n_child = sum(e.tag == elem.tag for e in elem)
@@ -1573,7 +1568,7 @@ def _h_start(reader: Reader, elem):
 
 @end("str:Hierarchy", only=False)
 def _h_end(reader: Reader, elem):
-    result = reader.nameable(
+    result: "v21.Hierarchy" = reader.nameable(
         reader.class_for_tag(elem.tag),
         elem,
         has_formal_levels=eval(elem.attrib.get("leveled", "false").title()),

sdmx/tests/convert/test_pandas.py

@@ -505,6 +505,18 @@ def expected(df, axis=0, cls=pd.DatetimeIndex):
         sdmx.to_pandas(ds, datetime=43)
 
 
+def test_dataset_empty() -> None:
+    """Dataset with 0 observations can be converted.
+
+    https://github.com/khaeru/sdmx/issues/251.
+    """
+    dsd = v21.DataStructureDefinition()
+    dsd.dimensions.getdefault(id="DIM_0")
+    ds = v21.DataSet(structured_by=dsd)
+
+    sdmx.to_pandas(ds)
+
+
 def test_list_of_obs(specimen) -> None:
     """Bare list of observations can be written."""
     with specimen("ng-ts.xml") as f: