Option to disable Zulu (Z) formatted date time representations

[aleehedl]

Django Rest Framework's DateTimeField component substitutes +00:00 with Z in to_representation method. While it's certainly valid ISO 8601, I find that format inconvenient since there is no built-in way in python to produce that. I usually encounter this while creating tests, and usually resort to rolling my own isoformat function.

assert serialized['created'] == obj.created.isoformat()  # Fails, Z vs +00:00
assert serialized['created'] == my_custom_isoformat(obj.created)  # Fine, but cumbersome.

The code responsible for the substitution can be found here:

django-rest-framework/rest_framework/fields.py

Line 1240 in fdb4931

value = value[:-6] + 'Z'

Do you think it would be worth it to have a setting which would bypass this substition?
Or should I always subclass the DateTimeField (with it's to_representation to my liking) and use it everywhere? Custom format string for the DateTimeField cannot be used to produce the +00:00 either.