🐛 Date(time) formats as dictated by Open Zaak EIGENSCHAP (SPECIFICATIE) with formaat: Datum or Datumtijd are not supported by zgw_consumers

[damm89]

General information
Zgw_consumers version: 0.16.1 (but also relevant in latest version)

Describe the bug
Open Zaak dictates that a date value of an EIGENSCHAP with EIGENSCHAP SPECIFICATIE formaat: Datum should have as its length 8. Zgw_consumers uses default python packages that don't support the format DICTATED by Open Zaak. Both of which use/support python 3.9. (3.11 does support YYYYMMDD)
The lines to blame:

zgw-consumers/zgw_consumers/api_models/catalogi.py

Line 112 in 229c5f7

EIGENSCHAP_FORMATEN = {

To Reproduce
Steps to reproduce the behavior:
In Open Zaak:

1. Create ZAAKTYPE
2. Create EIGENSCHAP for ZAAKTYPE (1) with a EIGENSCHAP SPECIFICATIE that has formaat: Datum (i.e. length must be 8).
3. Create ZAAK of ZAAKTYPE (1)
4. Create ZAAKEIGENSCHAP in ZAAK (3) with waarde: 20231004.

In consumer API:

Fetch zaakeigenschap en eigenschap.
Use factory from api_models and create a ZaakEigenschap instance with the Eigenschap instance as its eigenschap value.
Try zaakeigenschap.get_waarde().

Expected behavior
zgw_consumers to be aligned with Open Zaak within its respective supported python versions.

[sergei-maertens]

in my opinion this is a stupid construct in the standard for ZGW API's - the eigenschappen API design was rushed and not critically reviewed before accepting it. All other date/datetime formats in the API make use of the ISO-8601 international standard so I really fail to see why this format is allowed to be special.

That being said - I understand the challenges this creates. Feel free to submit a PR to fix this - in Maykin we are moving away to different API client organization and at some point we will re-evaluate how do deal with these domain data models.

On your end, you could monkeypatch this too by importing EIGENSCHAP_FORMATEN and setting a different cast function:

def weird_date_format(input: str):
    ...

EIGENSCHAP_FORMATEN ["datum"] = weird_date_format