Incorporated @stephprince suggestions on #1149.

CHANGELOG.md

@@ -11,9 +11,7 @@
 
 ### Bug fixes
 - Fixed issue where scalar datasets with a compound data type were being written as non-scalar datasets @stephprince [#1176](https://github.com/hdmf-dev/hdmf/pull/1176)
-
-### Bug fixes
-- Fix H5DataIO not exposing `maxshape` on non-dci dsets. @cboulay [#1149](https://github.com/hdmf-dev/hdmf/pull/1149)
+- Fixed H5DataIO not exposing `maxshape` on non-dci dsets. @cboulay [#1149](https://github.com/hdmf-dev/hdmf/pull/1149)
 
 ## HDMF 3.14.3 (July 29, 2024)
 

src/hdmf/backends/hdf5/h5_utils.py

@@ -21,7 +21,7 @@
 from ...query import HDMFDataset, ReferenceResolver, ContainerResolver, BuilderResolver
 from ...region import RegionSlicer
 from ...spec import SpecWriter, SpecReader
-from ...utils import docval, getargs, popargs, get_docval
+from ...utils import docval, getargs, popargs, get_docval, get_data_shape
 
 
 class HDF5IODataChunkIteratorQueue(deque):
@@ -681,6 +681,5 @@ def maxshape(self):
             return self.data.maxshape
         elif hasattr(self, "shape"):
             return self.shape
-        elif 'shape' in self.io_settings:
-            return self.io_settings['shape']
-        return None
+        else:
+            return get_data_shape(self.data)

tests/unit/test_io_hdf5_h5tools.py

@@ -604,15 +604,15 @@ def test_pass_through_of_chunk_shape_generic_data_chunk_iterator(self):
         dset = self.f["test_dataset"]
         self.assertEqual(dset.chunks, chunk_shape)
 
+    #############################################
+    #  H5DataIO general
+    #############################################
     def test_pass_through_of_maxshape_on_h5dataset(self):
         k = 10
         self.io.write_dataset(self.f, DatasetBuilder('test_dataset', np.arange(k), attributes={}))
         dset = H5DataIO(self.f['test_dataset'])
         self.assertEqual(dset.maxshape, (k,))
 
-    #############################################
-    #  H5DataIO general
-    #############################################
     def test_warning_on_non_gzip_compression(self):
         # Make sure no warning is issued when using gzip
         with warnings.catch_warnings(record=True) as w:
@@ -3769,6 +3769,14 @@ def test_dataio_shape_then_data(self):
         with self.assertRaisesRegex(ValueError, "Setting data when dtype and shape are not None is not supported"):
             dataio.data = list()
 
+    def test_dataio_maxshape(self):
+        dataio = H5DataIO(data=np.arange(10), maxshape=(None,))
+        self.assertEqual(dataio.maxshape, (None,))
+
+    def test_dataio_maxshape_from_data(self):
+        dataio = H5DataIO(data=[1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+        self.assertEqual(dataio.maxshape, (10,))
+
 
 def test_hdf5io_can_read():
     assert not HDF5IO.can_read("not_a_file")