More robust name validation

CHANGELOG.md

@@ -10,6 +10,10 @@ and this project adheres to [Semantic Versioning][].
 
 ## [0.x.x] - 2024-xx-xx
 
+### Changed
+
+-   Validation of element and column names allowing `_-.` and alphanumeric characters #624
+
 ### Minor
 
 -   Added `clip: bool = False` parameter to `polygon_query()` #670

docs/design_doc.md

@@ -130,6 +130,21 @@ _SpatialData_ follows the OME-NGFF specifications whenever possible and therefor
 -   Any `Element` MAY be annotated by `Tables`; also `Shapes` and `Points` MAY contain annotations within themselves as additional dataframe columns (e.g. intensity of point spread function of a each point, or gene id).
 -   `Tables` CAN NOT be annotated by other `Tables`.
 
+#### Naming
+
+Names of SpatialData elements must fulfill certain restrictions to ensure robust storage and compatibility:
+
+- MUST NOT be the empty string ``.
+- MUST only contain alphanumeric characters or hyphens `-`, dots `.`, underscores `_`. Alphanumeric includes letters from different alphabets and number-like symbols, but excludes whitespace, slashes and other symbols.
+- MUST NOT be the full strings `.` or `..`, which would have special meanings as file paths.
+- MUST NOT start with double underscores `__`.
+- MUST NOT only differ in character case, to avoid name collisions on case-insensitive systems.
+
+In tables, the above restrictions apply to the column names of `obs` and `var`, and to the key names of the `obsm`,
+`obsp`, `varm`, `varp`, `uns`, `layers` slots (for example `adata.obs['has space']` and `adata.layers['.']` are not
+allowed).
+Additionally, dataframes in tables MUST NOT have a column named `_index`, which is reserved.
+
 #### Images
 
 Images of a sample. Should conform to the [OME-NGFF concept of an image](https://ngff.openmicroscopy.org/latest/#image-layout).

src/spatialdata/_core/_elements.py

@@ -11,6 +11,7 @@
 from dask.dataframe import DataFrame as DaskDataFrame
 from geopandas import GeoDataFrame
 
+from spatialdata._core.validation import check_key_is_case_insensitively_unique, check_valid_name
 from spatialdata._types import Raster_T
 from spatialdata.models import (
     Image2DModel,
@@ -30,30 +31,30 @@ def __init__(self, shared_keys: set[str | None]) -> None:
         self._shared_keys = shared_keys
         super().__init__()
 
-    @staticmethod
-    def _check_valid_name(name: str) -> None:
-        if not isinstance(name, str):
-            raise TypeError(f"Name must be a string, not {type(name).__name__}.")
-        if len(name) == 0:
-            raise ValueError("Name cannot be an empty string.")
-        if not all(c.isalnum() or c in "_-" for c in name):
-            raise ValueError("Name must contain only alphanumeric characters, underscores, and hyphens.")
+    def _add_shared_key(self, key: str) -> None:
+        self._shared_keys.add(key)
+
+    def _remove_shared_key(self, key: str) -> None:
+        self._shared_keys.remove(key)
 
     @staticmethod
     def _check_key(key: str, element_keys: Iterable[str], shared_keys: set[str | None]) -> None:
-        Elements._check_valid_name(key)
+        check_valid_name(key)
         if key in element_keys:
             warn(f"Key `{key}` already exists. Overwriting it in-memory.", UserWarning, stacklevel=2)
         else:
-            if key in shared_keys:
-                raise KeyError(f"Key `{key}` already exists.")
+            try:
+                check_key_is_case_insensitively_unique(key, shared_keys)
+            except ValueError as e:
+                # Validation raises ValueError, but inappropriate mapping key must raise KeyError.
+                raise KeyError(*e.args) from e
 
     def __setitem__(self, key: str, value: Any) -> None:
-        self._shared_keys.add(key)
+        self._add_shared_key(key)
         super().__setitem__(key, value)
 
     def __delitem__(self, key: str) -> None:
-        self._shared_keys.remove(key)
+        self._remove_shared_key(key)
         super().__delitem__(key)
 
 

src/spatialdata/_core/spatialdata.py

@@ -22,6 +22,12 @@
 from xarray import DataArray
 
 from spatialdata._core._elements import Images, Labels, Points, Shapes, Tables
+from spatialdata._core.validation import (
+    check_all_keys_case_insensitively_unique,
+    check_target_region_column_symmetry,
+    check_valid_name,
+    validate_table_attr_keys,
+)
 from spatialdata._logging import logger
 from spatialdata._types import ArrayLike, Raster_T
 from spatialdata._utils import _deprecation_alias, _error_message_add_element
@@ -33,7 +39,6 @@
     PointsModel,
     ShapesModel,
     TableModel,
-    check_target_region_column_symmetry,
     get_model,
     get_table_keys,
 )
@@ -1115,6 +1120,12 @@ def _validate_can_safely_write_to_path(
                     " the current Zarr store." + WORKAROUND
                 )
 
+    def _validate_all_elements(self) -> None:
+        for element_type, element_name, element in self.gen_elements():
+            check_valid_name(element_name)
+            if element_type == "tables":
+                validate_table_attr_keys(element)
+
     def write(
         self,
         file_path: str | Path,
@@ -1150,6 +1161,7 @@ def write(
         if isinstance(file_path, str):
             file_path = Path(file_path)
         self._validate_can_safely_write_to_path(file_path, overwrite=overwrite)
+        self._validate_all_elements()
 
         store = parse_url(file_path, mode="w").store
         _ = zarr.group(store=store, overwrite=overwrite)
@@ -1244,9 +1256,7 @@ def write_element(
                 self.write_element(name, overwrite=overwrite)
             return
 
-        from spatialdata._core._elements import Elements
-
-        Elements._check_valid_name(element_name)
+        check_valid_name(element_name)
         self._validate_element_names_are_unique()
         element = self.get(element_name)
         if element is None:
@@ -1265,6 +1275,8 @@ def write_element(
                 break
         if element_type is None:
             raise ValueError(f"Element with name {element_name} not found in SpatialData object.")
+        if element_type == "tables":
+            validate_table_attr_keys(element)
 
         self._check_element_not_on_disk_with_different_type(element_type=element_type, element_name=element_name)
 
@@ -1316,10 +1328,9 @@ def delete_element_from_disk(self, element_name: str | list[str]) -> None:
                 self.delete_element_from_disk(name)
             return
 
-        from spatialdata._core._elements import Elements
         from spatialdata._io._utils import _backed_elements_contained_in_path
 
-        Elements._check_valid_name(element_name)
+        check_valid_name(element_name)
 
         if self.path is None:
             raise ValueError("The SpatialData object is not backed by a Zarr store.")
@@ -1451,10 +1462,8 @@ def write_transformations(self, element_name: str | None = None) -> None:
         element_name
             The name of the element to write. If None, write the transformations of all elements.
         """
-        from spatialdata._core._elements import Elements
-
         if element_name is not None:
-            Elements._check_valid_name(element_name)
+            check_valid_name(element_name)
 
         # recursively write the transformation for all the SpatialElement
         if element_name is None:
@@ -1541,10 +1550,8 @@ def write_metadata(self, element_name: str | None = None, consolidate_metadata:
         -----
         When using the methods `write()` and `write_element()`, the metadata is written automatically.
         """
-        from spatialdata._core._elements import Elements
-
         if element_name is not None:
-            Elements._check_valid_name(element_name)
+            check_valid_name(element_name)
 
         self.write_transformations(element_name)
         # TODO: write .uns['spatialdata_attrs'] metadata for AnnData.
@@ -1994,11 +2001,7 @@ def _validate_element_names_are_unique(self) -> None:
         ValueError
             If the element names are not unique.
         """
-        element_names = set()
-        for _, element_name, _ in self.gen_elements():
-            if element_name in element_names:
-                raise ValueError(f"Element name {element_name!r} is not unique.")
-            element_names.add(element_name)
+        check_all_keys_case_insensitively_unique([name for _, name, _ in self.gen_elements()])
 
     def _find_element(self, element_name: str) -> tuple[str, str, SpatialElement | AnnData]:
         """