IMASPython gets the list of IDSs from the latest DD tag

[imbeauf]

It seems that IMASPython reads the latest available DD tag (4.1.0 currently) to obtain the list of IDSs. This creates issues with the conversion of the dataset_description IDS, which has been removed in 4.1.0, even when trying to convert datasets between 3.x versions in which the IDS is existing. So the conversion would be legal and should preserve the dataset_description IDS instead of creating a bug.

Example on SDCC:
module load IMASPy
imas convert imas:hdf5?path=/work/imas/shared/imasdb/ITER/3/123332/1 3.42.0 imas:hdf5?path=/home/ITER/imbeauf/public/imasdb/task2e/ITER_SDB_SOLPS_converted
[01/20/26 15:30:13] INFO Parsing data dictionary version 4.1.0 dd_zip.py:89
INFO Parsing data dictionary version 3.42.0 dd_zip.py:89
0:00:00 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 0% Reading dataset_description/0 .
╭─────────────────────────────── Traceback (most recent call last) ────────────────────────────────╮
│ /home/ITER/imbeauf/.local/lib/python3.11/site-packages/imas/db_entry.py:565 in _get │
│ │
│ ❱ 565 │ │ │ raise IDSNameError(ids_name, self._ids_factory) │
╰──────────────────────────────────────────────────────────────────────────────────────────────────╯
IDSNameError: IDS 'dataset_description' does not exist.

[olivhoenen]

Interesting issue. And @maarten-ic has solved it already in #95, even if this PR was not targeting this problem in the first place (yes, he is that good 👏 ): loading the DD version if now deferred at the last moment when reading an IDS, while before it was loaded directly when opening the DBEntry (with latest available unless specified by the user).

So please use develop to allow reading/converting your data-entry without errors (a new release 2.2.0 will be prepared in the coming few days). Or if you're stuck with a previous release for somewhat reason, note that you can still circumvent the issue by forcing a compatible default version of the DD by setting IMAS_VERSION to it in your environment, e.g.

IMAS_VERSION=3.42.0 imas convert imas:hdf5?path=/work/imas/shared/imasdb/ITER/3/123332/1 3.42.0 imas:hdf5?path=/home/ITER/imbeauf/public/imasdb/task2e/ITER_SDB_SOLPS_converted