Make () the default value for AxisQuery.coords. (#136)

Since `coords` values are no longer `Optional` (and the `(slice(None),)`
workaround is no longer needed), this updates the declared API for
AxisQuery to also not be `Optional` (i.e., to request everything,
the `()` should be used).

python-spec/src/somacore/options.py

@@ -120,7 +120,9 @@ class ResultOrder(enum.Enum):
 DenseNDCoords = Sequence[DenseCoord]
 """A sequence of ranges to read dense data."""
 
-# TODO: Add support for types other than int/string
+# TODO: Add support for non-integer types.
+# NOTE: Keep this in sync with the types accepted in `_canonicalize_coord`
+# in ./query/axis.py.
 # https://github.com/single-cell-data/TileDB-SOMA/issues/960
 SparseDFCoord = Union[
     DenseCoord,

python-spec/src/somacore/query/axis.py

@@ -9,30 +9,31 @@
 
 
 def _canonicalize_coords(
-    in_coords: Optional[options.SparseDFCoords],
+    in_coords: options.SparseDFCoords,
 ) -> Tuple[options.SparseDFCoord, ...]:
     """Validates coordinates and freezes sequences as tuples.
 
     This is not strictly necessary; DataFrame will report these errors
     eventually but doing it now makes for better UX.
     """
-    if in_coords is None:
-        return (slice(None),)
-    if not isinstance(in_coords, Sequence):
+    if types.is_nonstringy_sequence(in_coords):
+        return tuple(_canonicalize_coord(c) for c in in_coords)
+    if isinstance(in_coords, (str, bytes)):
         raise TypeError(
-            f"query coordinates must be a sequence, not a single {type(in_coords)}"
+            "Query coordinates must be a normal sequence, not `str` or `bytes`."
+            f" Did you mean {(in_coords,)}?"
         )
-    if not types.is_nonstringy_sequence(in_coords):
-        raise TypeError(
-            "query coordinates must be a normal sequence, not `str` or `bytes`."
-        )
-    return tuple(_canonicalize_coord(c) for c in in_coords)
+    raise TypeError(
+        f"Query coordinates must be a sequence, not a single {type(in_coords)}"
+    )
 
 
 def _canonicalize_coord(coord: options.SparseDFCoord) -> options.SparseDFCoord:
     """Validates a single coordinate, freezing mutable sequences."""
+    # NOTE: Keep this in sync with the `SparseDFCoord` type.
     if coord is None or isinstance(
-        coord, (bytes, int, slice, str, pa.Array, pa.ChunkedArray, np.ndarray)
+        coord,
+        (bytes, int, slice, str, pa.Array, pa.ChunkedArray, np.ndarray),
     ):
         return coord
     if isinstance(coord, Sequence):
@@ -59,13 +60,12 @@ class AxisQuery:
     Examples::
 
         AxisQuery()  # all data
-        AxisQuery(coords=None)  # also all data
+        AxisQuery(coords=())  # also all data
         AxisQuery(coords=(slice(1,10),))  # 1D, slice
         AxisQuery(coords=([0,1,2]))  # 1D, point indexing using array-like
         AxisQuery(coords=(slice(None), numpy.array([0,88,1001])))  # 2D
         AxisQuery(value_filter="tissue == 'lung'")
         AxisQuery(coords=(slice(1,None),), value_filter="tissue == 'lung'")
-    ```
     """
 
     value_filter: Optional[str] = attrs.field(
@@ -74,7 +74,7 @@ class AxisQuery:
     )
     """A string specifying a SOMA ``value_filter``."""
     coords: Tuple[options.SparseDFCoord, ...] = attrs.field(
-        default=(slice(None),),
+        default=(),
         converter=_canonicalize_coords,
     )
     """Query (slice) by dimension.

python-spec/testing/test_query_axis.py

@@ -11,6 +11,7 @@
 @mark.parametrize(
     ["coords", "want"],
     [
+        ((), ()),
         ((slice(1, 10),), (slice(1, 10),)),
         ([0, 1, 2], (0, 1, 2)),
         ((slice(None), [0, 88, 1001]), (slice(None), (0, 88, 1001))),