relax layer name constraints (#1402)

* relax layer name constraints

* revert attachment check

* revert attachment eq

* diag

* better num_channel detection

* changelog

Author: normanrz

webknossos/Changelog.md

@@ -17,6 +17,8 @@ For upgrade instructions, please check the respective _Breaking Changes_ section
 ### Added
 
 ### Changed
+- Relaxed layer name validation to match WEBKNOSSOS behavior. [#1402](https://github.com/scalableminds/webknossos-libs/pull/1402)
+- Better heuristic for detecting number of channels, when `numChannels` is missing. [#1402](https://github.com/scalableminds/webknossos-libs/pull/1402)
 
 ### Fixed
 - Fix mag and attachment paths in Zarr annotation volume layer export. [#1401](https://github.com/scalableminds/webknossos-libs/pull/1401)

webknossos/webknossos/dataset/dataset.py

@@ -146,6 +146,15 @@ def _find_array_info(layer_path: UPath) -> ArrayInfo | None:
     return None
 
 
+def _validate_layer_name(layer_name: str) -> None:
+    from webknossos.dataset.layer.abstract_layer import _ALLOWED_LAYER_NAME_REGEX
+
+    if _ALLOWED_LAYER_NAME_REGEX.match(layer_name) is None:
+        raise ValueError(
+            f"The layer name '{layer_name}' is invalid. It must only contain letters, numbers, underscores, hyphens and dots."
+        )
+
+
 class Dataset(AbstractDataset[Layer, SegmentationLayer]):
     """A dataset is the entry point of the Dataset API.
 
@@ -419,9 +428,12 @@ def _SegmentationLayerType(self) -> type[SegmentationLayer]:
     def _initialize_layer_from_properties(
         self, properties: LayerProperties, read_only: bool
     ) -> Layer:
-        # If the numChannels key is not present in the dataset properties, assume it is 1.
+        # If the numChannels key is not present in the dataset properties, assume it is 1 unless we have uint24.
         if properties.num_channels is None:
-            properties.num_channels = 1
+            if properties.element_class == "uint24":
+                properties.num_channels = 3
+            else:
+                properties.num_channels = 1
         return super()._initialize_layer_from_properties(properties, read_only)
 
     @classmethod
@@ -1052,6 +1064,8 @@ def add_layer(
 
         self._ensure_writable()
 
+        _validate_layer_name(layer_name)
+
         if num_channels is None:
             num_channels = 1
 
@@ -1243,6 +1257,8 @@ def add_layer_like(
     ) -> Layer:
         self._ensure_writable()
 
+        _validate_layer_name(layer_name)
+
         if layer_name in self.layers.keys():
             raise IndexError(
                 f"Adding layer {layer_name} failed. There is already a layer with this name"
@@ -1339,6 +1355,8 @@ def add_layer_for_existing_files(
             Magnifications are discovered automatically.
         """
         self._ensure_writable()
+
+        _validate_layer_name(layer_name)
         assert layer_name not in self.layers, f"Layer {layer_name} already exists!"
 
         array_info = _find_array_info(self.path / layer_name)
@@ -1445,6 +1463,8 @@ def add_layer_from_images(
         * `truncate_rgba_to_rgb`: only applies if `allow_multiple_layers=True`, set to `False` to write four channels into layers instead of an RGB channel
         * `executor`: pass a `ClusterExecutor` instance to parallelize the conversion jobs across the batches
         """
+
+        _validate_layer_name(layer_name)
         if category is None:
             image_path_for_category_guess: UPath
             if (
@@ -1965,6 +1985,8 @@ def add_layer_as_copy(
 
         if new_layer_name is None:
             new_layer_name = foreign_layer.name
+        else:
+            _validate_layer_name(new_layer_name)
 
         if exists_ok:
             layer = self.get_or_add_layer(
@@ -2192,6 +2214,8 @@ def add_layer_as_ref(
 
         if new_layer_name is None:
             new_layer_name = foreign_layer.name
+        else:
+            _validate_layer_name(new_layer_name)
 
         if new_layer_name in self.layers.keys():
             raise IndexError(

webknossos/webknossos/dataset/layer/abstract_layer.py

@@ -70,7 +70,7 @@ def _dtype_per_layer_to_dtype_per_channel(
         )
     except TypeError as e:
         raise TypeError(
-            "Converting dtype_per_layer to dtype_per_channel failed. Double check if the dtype_per_layer value is correct."
+            f"Converting dtype_per_layer to dtype_per_channel failed. Double check if the dtype_per_layer value is correct. Got {dtype_per_layer} and {num_channels} channels."
         ) from e
 
 
@@ -111,8 +111,8 @@ def __init__(
         # It is possible that the properties on disk do not contain the number of channels.
         # Therefore, the parameter is optional. However at this point, 'num_channels' was already inferred.
         assert properties.num_channels is not None
-        assert _ALLOWED_LAYER_NAME_REGEX.match(properties.name), (
-            f"The layer name '{properties.name}' is invalid. It must only contain letters, numbers, underscores, hyphens and dots."
+        assert "/" not in properties.name and not properties.name.startswith("."), (
+            f"The layer name '{properties.name}' is invalid."
         )
         self._dataset = dataset
         self._name: str = properties.name  # The name is also stored in the properties, but the name is required to get the properties.

webknossos/webknossos/dataset/layer/layer.py

@@ -224,7 +224,7 @@ def name(self, layer_name: str) -> None:
         Renames the layer to `layer_name`. This changes the name of the directory on disk and updates the properties.
         Only layers on local file systems can be renamed.
         """
-        from webknossos.dataset.layer.abstract_layer import _ALLOWED_LAYER_NAME_REGEX
+        from webknossos.dataset.dataset import _validate_layer_name
 
         if layer_name == self.name:
             return
@@ -235,10 +235,8 @@ def name(self, layer_name: str) -> None:
             raise ValueError(
                 f"Failed to rename layer {self.name} to {layer_name}: The new name already exists."
             )
-        if _ALLOWED_LAYER_NAME_REGEX.match(layer_name) is None:
-            raise ValueError(
-                f"The layer name '{layer_name}' is invalid. It must only contain letters, numbers, underscores, hyphens and dots."
-            )
+
+        _validate_layer_name(layer_name)
 
         if self.path.exists():
             assert is_fs_path(self.dataset.path), (