Make Django Rest Framework correctly handle Django ValidationError raised in the save method of a model

drf_utils.py

"""
Sometimes in your Django model you want to raise a ``ValidationError`` in the ``save`` method, for
some reason.
This exception is not managed by Django Rest Framework because it occurs after its validation 
process. So at the end, you'll have a 500.
Correcting this is as simple as overriding the exception handler, by converting the Django
``ValidationError`` to a DRF one.
"""

from django.core.exceptions import ValidationError as DjangoValidationError

from rest_framework.exceptions import ValidationError as DRFValidationError
from rest_framework.views import exception_handler as drf_exception_handler


def exception_handler(exc, context):
    """Handle Django ValidationError as an accepted exception

    Must be set in settings:

    >>> REST_FRAMEWORK = {
    ...     # ...
    ...     'EXCEPTION_HANDLER': 'mtp.apps.common.drf.exception_handler',
    ...     # ...
    ... }

    For the parameters, see ``exception_handler``

    """

    if isinstance(exc, DjangoValidationError):
        exc = DRFValidationError(detail=exc.message_dict)

    return drf_exception_handler(exc, context)

Where could I be going wrong?

Hard to say without seeing your adaption.

Very helpful snippet. Thanks!

If you think about it... this must have been done already.
As DRF has this ModelSerializer, which magically handles Django's validation just fine (like the ones raised by Model.clean method as well as the validators you specified for your fields)

Here's where the magic happens:

https://github.com/encode/django-rest-framework/blob/master/rest_framework/fields.py
rest_framework.fields.get_error_detail

and here is where it's used, very nicely implemented.

rest_framework.fields.Field.run_validators
https://github.com/encode/django-rest-framework/blob/master/rest_framework/fields.py

and rest_framework.serializers.Serializer.as_serializer_error
https://github.com/encode/django-rest-framework/blob/master/rest_framework/serializers.py

You should be able to handle it like this:

from django.core.exceptions import ValidationError as DjangoValidationError
from rest_framework.exceptions import ValidationError as DRFValidationError
from rest_framework.views import exception_handler as drf_exception_handler
from rest_framework.fields import get_error_detail


def exception_handler(exc, context):
    if isinstance(exc, DjangoValidationError):
        exc = DRFValidationError(detail=get_error_detail(exc))

    return drf_exception_handler(exc, context)

Please what is the context and how do I pass that to the django view?