Deserialization of RangeFields not interpreting the range bounds into Python types

[Sebastian Albert]

I ran into an issue using Django REST Framework on a simple model with a field of type DateRangeField:
When POSTing a new instance to DRFs list view via a JSON body with the field's key mapped to the value ["2025-04-14", "2025-05-15"]
the new instance is saved, but the immediately returned page is an error, indicating that .isoformat() has been called on an object of type str [1], which is "2025-04-14" in my example. Apparently, the RangeField deserialization [2] did not deserialize the range bounds into the type of the Range's base_field [3]. psycopg seems to handle this without issue, but as the deserialized object is used in the view to be serialized again, this doesn't work out.

I am entirely new to Django, but from what I understand, I *think* the instance of DateRangeField should have bounds of type date and not str.

Retrieving the successfully saved entity via a subsequent GET works fine, which is in line with that reasoning, as psycopg returns Postgres' daterange bounds as date instances.

[1] ​https://github.com/django/django/blob/5.2/django/contrib/postgres/fields/ranges.py#L128
[2] ​https://github.com/django/django/blob/5.2/django/contrib/postgres/fields/ranges.py#L98-L108
[2] ​https://github.com/django/django/blob/5.2/django/contrib/postgres/fields/ranges.py#L204

[Natalia Bidart]

Hello Sebastian, thank you for taking the time to create this report. In order to continue this ticket triage, we would need a way to reproduce the issue using Django without requiring any other dependency. Ideally, could you provide a test case for the Django codebase showcasing the issue and the expected outcome? Or, a minimal Django test project and detailed instructions to reproduce would also help.

Please feel free to reopen when a reproducer is provided for us to continue the triaging process. Cheers!