fix: validate v3 dtypes when loading/creating v3 metadata

pyproject.toml

@@ -274,6 +274,7 @@ filterwarnings = [
     "ignore:PY_SSIZE_T_CLEAN will be required.*:DeprecationWarning",
     "ignore:The loop argument is deprecated since Python 3.8.*:DeprecationWarning",
     "ignore:Creating a zarr.buffer.gpu.*:UserWarning",
+    "ignore:Duplicate name:UserWarning",  # from ZipFile
 ]
 markers = [
     "gpu: mark a test as requiring CuPy and GPU"

src/zarr/core/array_spec.py

@@ -3,7 +3,7 @@
 from dataclasses import dataclass
 from typing import TYPE_CHECKING, Any, Literal
 
-from zarr.core.common import parse_dtype, parse_fill_value, parse_order, parse_shapelike
+from zarr.core.common import parse_fill_value, parse_order, parse_shapelike
 
 if TYPE_CHECKING:
     import numpy as np
@@ -29,12 +29,11 @@ def __init__(
         prototype: BufferPrototype,
     ) -> None:
         shape_parsed = parse_shapelike(shape)
-        dtype_parsed = parse_dtype(dtype)
         fill_value_parsed = parse_fill_value(fill_value)
         order_parsed = parse_order(order)
 
         object.__setattr__(self, "shape", shape_parsed)
-        object.__setattr__(self, "dtype", dtype_parsed)
+        object.__setattr__(self, "dtype", dtype)
         object.__setattr__(self, "fill_value", fill_value_parsed)
         object.__setattr__(self, "order", order_parsed)
         object.__setattr__(self, "prototype", prototype)

src/zarr/core/common.py

@@ -19,8 +19,6 @@
 if TYPE_CHECKING:
     from collections.abc import Awaitable, Callable, Iterator
 
-import numpy as np
-import numpy.typing as npt
 
 ZARR_JSON = "zarr.json"
 ZARRAY_JSON = ".zarray"
@@ -155,11 +153,6 @@ def parse_shapelike(data: int | Iterable[int]) -> tuple[int, ...]:
     return data_tuple
 
 
-def parse_dtype(data: npt.DTypeLike) -> np.dtype[Any]:
-    # todo: real validation
-    return np.dtype(data)
-
-
 def parse_fill_value(data: Any) -> Any:
     # todo: real validation
     return data

src/zarr/core/metadata/v2.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from collections.abc import Iterable
+from enum import Enum
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
@@ -21,7 +22,7 @@
 from zarr.core.array_spec import ArraySpec
 from zarr.core.chunk_grids import RegularChunkGrid
 from zarr.core.chunk_key_encodings import parse_separator
-from zarr.core.common import ZARRAY_JSON, ZATTRS_JSON, parse_dtype, parse_shapelike
+from zarr.core.common import ZARRAY_JSON, ZATTRS_JSON, parse_shapelike
 from zarr.core.config import config, parse_indexing_order
 from zarr.core.metadata.common import ArrayMetadata, parse_attributes
 
@@ -100,9 +101,24 @@ def _json_convert(
                 else:
                     return o.descr
             if np.isscalar(o):
-                # convert numpy scalar to python type, and pass
-                # python types through
-                return getattr(o, "item", lambda: o)()
+                out: Any
+                if hasattr(o, "dtype") and o.dtype.kind == "M" and hasattr(o, "view"):
+                    # https://github.com/zarr-developers/zarr-python/issues/2119
+                    # `.item()` on a datetime type might or might not return an
+                    # integer, depending on the value.
+                    # Explicitly cast to an int first, and then grab .item()
+                    out = o.view("i8").item()
+                else:
+                    # convert numpy scalar to python type, and pass
+                    # python types through
+                    out = getattr(o, "item", lambda: o)()
+                    if isinstance(out, complex):
+                        # python complex types are not JSON serializable, so we use the
+                        # serialization defined in the zarr v3 spec
+                        return [out.real, out.imag]
+                return out
+            if isinstance(o, Enum):
+                return o.name
             raise TypeError
 
         zarray_dict = self.to_dict()
@@ -157,6 +173,11 @@ def update_attributes(self, attributes: dict[str, JSON]) -> Self:
         return replace(self, attributes=attributes)
 
 
+def parse_dtype(data: npt.DTypeLike) -> np.dtype[Any]:
+    # todo: real validation
+    return np.dtype(data)
+
+
 def parse_zarr_format(data: object) -> Literal[2]:
     if data == 2:
         return 2