Support get_class and roundtrip on datetime datasets by rly · Pull Request #1313 · hdmf-dev/hdmf

rly · 2025-09-19T21:04:02Z

Motivation

Fixes #429. Related to (now-merged) #1312.

Previously, neurodata types with isodatetime/datetime datasets could not be roundtripped through get_class-generated classes without manually wiring up an @ObjectMapper.constructor_arg converter to parse the stored ISO string back into a datetime. This PR makes that work end to end.

What changed

Write path. New _isoformat dtype helper converts datetime/date values to ASCII-encoded ISO bytes on write so they land as fixed-length text in HDF5.
Read path. New _parse_isoformat parses stored values back to datetime (or date for date-only strings) for any dataset/attribute whose spec declares dtype='isodatetime' or dtype='datetime', including arrays.
Inc-site dtype overrides. construct() now accepts an optional spec_ext so a parent group that declares dtype='isodatetime' on a data_type_inc-extending dataset whose own def has no dtype is honored on read. spec_ext is plumbed through classgenerator, manager, and objectmapper.
Scalar datetime in generated classes. The scalar_data docval macro now includes datetime/date, so get_class-generated dtype-less classes accept scalar datetime values without per-class shims.
Test scaffolding. _assert_data_equal skips the length comparison for scalar Data (a 0-d datetime has no len), preventing false negatives in roundtrip assertions.

How to test

The new tests cover the main paths:

tests/unit/build_tests/mapper_tests/test_build_datetime.py — datetime/date build round-trips for both regular specs and extension specs (ported from [WIP] Fix building datetime datasets with data_type_inc #1314).
tests/unit/test_hdf5_roundtrip_extensions.py — full HDF5 roundtrip including the inc-site dtype override case.
tests/unit/build_tests/test_classgenerator.py — get_class with datetime fields, including scalar datetime acceptance via the widened scalar_data macro.

pytest tests/unit/build_tests/mapper_tests/test_build_datetime.py \
       tests/unit/test_hdf5_roundtrip_extensions.py \
       tests/unit/build_tests/test_classgenerator.py

Checklist

Did you update CHANGELOG.md with your changes?
Does the PR clearly describe the problem and the solution?
Have you reviewed our Contributing Guide?
Does the PR use "Fix #XXX" notation to tell GitHub to close the relevant issue numbered XXX when the PR is merged?

codecov · 2025-09-19T21:05:36Z

Codecov Report

❌ Patch coverage is 69.51220% with 25 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.97%. Comparing base (f82893b) to head (349602f).

Files with missing lines	Patch %	Lines
src/hdmf/build/objectmapper.py	65.95%	9 Missing and 7 partials ⚠️
src/hdmf/build/classgenerator.py	67.85%	6 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1313      +/-   ##
==========================================
- Coverage   93.17%   92.97%   -0.21%     
==========================================
  Files          41       41              
  Lines       10099    10158      +59     
  Branches     2079     2099      +20     
==========================================
+ Hits         9410     9444      +34     
- Misses        413      428      +15     
- Partials      276      286      +10

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_isoformat was returning a Python str while convert_dtype labeled the result as the 'ascii' dtype. Encode to bytes (matching _ascii's contract) so the scalar branch produces the expected b'YYYY-MM-DDTHH:MM:SS' values. Also handle str and bytes passthrough for idempotence when __convert_string has already pre-converted the value. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Add Column (Data) and BarWithColumnData (Container) helper classes and two tests exercising build of datetime/date values through a dataset spec with data_type_inc set. test_date_array_ext_spec specifically mirrors the traceback in #1311. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Add _parse_isoformat helper (reverse of _isoformat) and wire it into __get_subspec_values so attributes and dataset data with isodatetime/datetime dtype are converted from stored ISO str/bytes back into datetime/date before being passed to the container constructor. Also applied to Data containers' direct const_args['data'] assignment in construct(). Scoped to scalar values; inc-site dtype override and array datasets are not yet handled. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

- Pass ignore_name/ignore_hdmf_attrs to assertContainerEqual so the top-level 'root' vs 'my_group' name mismatch and read-time object_id reassignment don't fail the equality check. - my_data3 has no data_type_inc, so it is stored as a named scalar dataset field on the group and read back as a plain datetime value. Assert against the value directly rather than .data. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

construct() now accepts an optional spec_ext (parallel to build()) that carries per-site overrides from the parent's subspec. Threaded through BuildManager.construct, TypeMap.construct, and ObjectMapper.construct. The Data-container construct path uses spec_ext for dtype resolution when the base def has no dtype, so a parent group spec like DatasetSpec(data_type_inc='X', dtype='datetime', ...) correctly drives datetime parsing on read even when X's def declares no dtype. __get_sub_builders passes the inc-site subspec as spec_ext at the construct call site. spec_ext defaults to None to preserve backward compatibility with all existing call sites. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Data containers can wrap scalar values (e.g., a single datetime) for which len() is not defined. Gate the length comparison on _is_collection so the helper works for both scalar and collection-valued Data instances. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scalar_data now includes datetime.datetime and datetime.date so generated classes for dtype-less DatasetSpecs accept scalar datetime values on construct (read path) and on user-side construction (write path). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

- classgenerator: update inherited `data` docval arg in place so subclasses preserve parent-set keys like `default` (e.g., VectorData -> []) - objectmapper: extend __parse_datetime_on_read to handle lists, tuples, numpy arrays, and h5py.Dataset by eager materialization - test_hdf5_roundtrip_extensions: clean imports/dead setup and add an array roundtrip test - test_classgenerator: regression test that subclasses preserve a parent's `data` default Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Adds a write-once `resolved_spec` property on the base `Builder` class so the build and read paths can record which subspec each builder was matched to. Defaults to None, matches the existing `parent` and `source` setter discipline (raises on overwrite). No callers wired up yet; follow-up phases migrate the matchers and consumers. Includes resolved_specs_epic.md as the planning doc for the full multi-phase refactor that supersedes the spec_ext plumbing in #1313. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Introduces the first read-time consumer of `builder.resolved_spec`: attributes and datasets whose spec declares `dtype='isodatetime'` or `dtype='datetime'` are parsed back into Python `datetime` / `date` objects on construct. * Adds `_parse_isoformat` module helper. * Adds `ObjectMapper.__parse_datetime_on_read` static method handling scalars, lists/tuples, numpy arrays, h5py datasets, and zarr arrays via the numpy array protocol. * Wires the consumer into three sites: - attribute reads in `__get_subspec_values` (attribute specs are already position-resolved). - the inline DatasetSpec branch in `__get_subspec_values`, using `builder.resolved_spec or spec`. - `ObjectMapper.construct` for `Data` containers, using `builder.resolved_spec or self.spec`. This subsumes the read-side functionality of #1313 without the `spec_ext` plumbing on `BuildManager.construct` / `TypeMap.construct` / `ObjectMapper.construct`. The DynamicTable column case (a VectorData column whose parent's inc-site declares `dtype='isodatetime'`) reads back as datetime values via Phase 2's matcher writing to `resolved_spec`. Stacked on #1449. Part of #1448. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Introduces the first read-time consumer of `builder.matched_spec`: attributes and datasets whose spec declares `dtype='isodatetime'` or `dtype='datetime'` are parsed back into Python `datetime` / `date` objects on construct. * Adds `_parse_isoformat` module helper. * Adds `ObjectMapper.__parse_datetime_on_read` static method handling scalars, lists/tuples, numpy arrays, h5py datasets, and zarr arrays via the numpy array protocol. * Wires the consumer into three sites: - attribute reads in `__get_subspec_values` (attribute specs are already position-resolved). - the inline DatasetSpec branch in `__get_subspec_values`, using `builder.matched_spec or spec`. - `ObjectMapper.construct` for `Data` containers, using `builder.matched_spec or self.spec`. This subsumes the read-side functionality of #1313 without the `spec_ext` plumbing on `BuildManager.construct` / `TypeMap.construct` / `ObjectMapper.construct`. The DynamicTable column case (a VectorData column whose parent's inc-site declares `dtype='isodatetime'`) reads back as datetime values via Phase 2's matcher writing to `matched_spec`. Stacked on #1449. Part of #1448. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

rly added 3 commits April 7, 2025 16:55

Stash progress

07984bb

Merge branch 'dev' into get_class_datetime

991c5a2

Add roundtrip test file (WIP)

2e58aa2

rly mentioned this pull request Sep 19, 2025

[WIP] Fix building datetime datasets with data_type_inc #1314

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4 tasks

rly and others added 12 commits February 11, 2026 22:14

Merge branch 'dev' into get_class_datetime

7a73659

Merge branch 'dev' into get_class_datetime

2f075fa

Add changelog entry for datetime dataset fixes

b4ee5e2

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Expand changelog entry to cover read and inc-site dtype override

f8a0e07

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

rly changed the title ~~[WIP] Support get_class and roundtrip on datetime datasets~~ Support get_class and roundtrip on datetime datasets Apr 26, 2026

rly marked this pull request as ready for review April 26, 2026 05:44

rly mentioned this pull request Apr 26, 2026

Refactor spec_ext phase 1: add matched_spec slot to Builder #1447

Open

3 tasks

This was referenced Apr 26, 2026

Refactor: matched specs on builders (replace spec_ext plumbing) #1448

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Refactor spec_ext phase 3: parse isodatetime/datetime values on read via matched_spec #1450

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Support get_class and roundtrip on datetime datasets#1313

Support get_class and roundtrip on datetime datasets#1313
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rly commented Sep 19, 2025 •

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rly commented Sep 19, 2025 •

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