Fix saving of AwkwardArrayView (#1736)

* Add testcase

* Make copy of view before saving

* Add release notes

* (chore): use `obsm_types`

---------

Co-authored-by: ilan-gold <[email protected]>

docs/release-notes/1736.bugfix.md

@@ -0,0 +1,2 @@
+Ensure that views of AwkwardArrays have their "view" attributes removed on saving an {class}`~anndata.AnnData` object
+to disk. {user}`grst`

src/anndata/_io/specs/methods.py

@@ -2,6 +2,7 @@
 
 import warnings
 from collections.abc import Mapping
+from copy import copy
 from functools import partial
 from itertools import product
 from types import MappingProxyType
@@ -792,6 +793,9 @@ def write_awkward(
     from anndata.compat import awkward as ak
 
     group = f.require_group(k)
+    if isinstance(v, views.AwkwardArrayView):
+        # copy to remove the view attributes
+        v = copy(v)
     form, length, container = ak.to_buffers(ak.to_packed(v))
     group.attrs["length"] = length
     group.attrs["form"] = form.to_json()

tests/test_awkward.py

@@ -15,6 +15,7 @@
     ImplicitModificationWarning,
     read_h5ad,
 )
+from anndata.compat import AwkArray
 from anndata.compat import awkward as ak
 from anndata.tests.helpers import assert_equal, gen_adata, gen_awkward
 from anndata.utils import axis_len
@@ -249,6 +250,22 @@ def test_awkward_io(tmp_path, array):
     assert_equal(adata.uns["awk"], adata2.uns["awk"], exact=True)
 
 
+def test_awkward_io_view(tmp_path):
+    """Check that views are converted to actual arrays on save, i.e. the _view_args and __list__ parameters are removed"""
+    adata = gen_adata((3, 3), varm_types=(), obsm_types=(AwkArray,), layers_types=())
+
+    v = adata[1:]
+    adata_path = tmp_path / "adata.h5ad"
+    v.write_h5ad(adata_path)
+
+    adata2 = read_h5ad(adata_path)
+    # parameters are not fully removed, but set to None
+    assert ak.parameters(adata2.obsm["awk_2d_ragged"]) == {
+        "__list__": None,
+        "_view_args": None,
+    }
+
+
 # @pytest.mark.parametrize("join", ["outer", "inner"])
 @pytest.mark.parametrize(
     ("arrays", "join", "expected"),