[BUG] iso8601 is a required field

[Erikpostt]

I don't quite remember why we made the iso_8601 fields obligatory when storing metadata, but perhaps we want to reconsider this as it is not always relevant (perhaps only for longitudinal studies).

Describe the Bug
For the publication of the first paper on arm swing, we are using a different dataset which does not have any dates/times attached to it. I would like to store it as tsdf though.

To Reproduce
Steps to reproduce the behavior:

1. Create a metadata variable without the start_iso8601 and end_iso8601 fields
2. Append the metadata to the list of metafiles: l_metafiles.append(tsdf.write_binary_file(path_output, f"values.bin", data_sensors, metadata_sensor))

Expected Behavior
The metadata is stored without an iso8601 field.

Actual Behavior
TSDFMetadataFieldError: Value for the obligatory TSDF field 'start_iso8601' is missing in the provided TSDF metadata file.

tsdf Version

• 0.5.2

Environment Details

• OS: Windows
• Python Version: 3.11.5

[kretep]

The _iso8601 fields are obligatory as specified in the TSDF format specification (see https://arxiv.org/abs/2211.11294). So in order to keep the library in-line with the format, I don't think we'll change this. You could perhaps consider using a dummy date.