Permit true-ASCII attributes in non-from-pandas dataframes (#1337)

* When creating an attribute of dtype "ascii", `var` should be defaulted to `True`

Author: johnkerl

HISTORY.md

@@ -1,6 +1,7 @@
 # In Progress
 
 ## API Changes
+* Permit true-ASCII attributes in non-from-pandas dataframes [#1337](https://github.com/TileDB-Inc/TileDB-Py/pull/1337)
 * Addition of `Array.upgrade_version` to upgrade array to latest version [#1334](https://github.com/TileDB-Inc/TileDB-Py/pull/1334)
 * Attributes in query conditions no longer need to be passed to `Array.query`'s `attr` arg [#1333](https://github.com/TileDB-Inc/TileDB-Py/pull/1333)
 * `ArraySchemaEvolution` checks context's last error for error message [#1335](https://github.com/TileDB-Inc/TileDB-Py/pull/1335)

tiledb/libtiledb.pyx

@@ -1534,6 +1534,8 @@ cdef class Attr(object):
         if isinstance(dtype, str) and dtype == "ascii":
             tiledb_dtype = TILEDB_STRING_ASCII
             ncells = TILEDB_VAR_NUM
+            if var is None:
+                var = True
         else:
             _dtype = np.dtype(dtype)
             tiledb_dtype, ncells = array_type_ncells(_dtype)

tiledb/tests/test_libtiledb.py

@@ -526,7 +526,15 @@ def test_ascii_attribute(self, sparse, capfd):
         dom = tiledb.Domain(
             tiledb.Dim(name="d", domain=(1, 4), tile=1, dtype=np.uint32)
         )
-        attrs = [tiledb.Attr(name="A", dtype="ascii", var=True)]
+
+        with pytest.raises(TypeError) as exc_info:
+            tiledb.Attr(name="A", dtype="ascii", var=False)
+        assert (
+            str(exc_info.value) == "dtype is not compatible with var-length attribute"
+        )
+
+        attrs = [tiledb.Attr(name="A", dtype="ascii")]
+
         schema = tiledb.ArraySchema(domain=dom, attrs=attrs, sparse=sparse)
         tiledb.Array.create(path, schema)
 
@@ -547,6 +555,7 @@ def test_ascii_attribute(self, sparse, capfd):
             assert A.schema.nattr == 1
             A.schema.dump()
             assert_captured(capfd, "Type: STRING_ASCII")
+            assert A.schema.attr("A").isvar
             assert A.schema.attr("A").dtype == np.bytes_
             assert A.schema.attr("A").isascii
             assert_array_equal(A[:]["A"], np.asarray(ascii_data, dtype=np.bytes_))