Why does FileField.to_representation return null for non-null values?

[Lucianod28]

Django's FileField(null=False, blank=True), stores "" in the DB when there's no file. DRF currently serializes this to null due to a falsy check in to_representation:

if not value:
    return None

This is wrong because the field has null/allow_null=False. Is this intentional or would a PR fixing this be welcome?

[browniebroke]

My guess: from a REST API perspective or by being framework/language agnostic (ignoring Django's choice), the null value represent better the absence of a thing than an empty string. As consumers of your DRF endpoints are unlikely to be a Django backend, I would argue that null is better in this case.

[Lucianod28]

Here's a clearer example that I think shows it's not related to Django:

>>> from rest_framework import serializers
>>> class TestSerializer(serializers.Serializer):
...     file = serializers.FileField(allow_null=False)
>>> TestSerializer({"file": ""}).data
{'file': None}

The serializer converts an empty string to null. Not only is this undocumented, but if you generate a schema with drf-spectacular, the schema does not allow null, so your consumers will receive an unexpected null value.