Design pattern for DRY approach to dynamic serializer fields - django-rest-framework

Question

Basically, what I want to achieve is to make the list of fields in a serializer be optionally dynamic depending on whether the user has provided the list of fields they are interested in.
Here's my serializer for DRF serializer:
class DynamicFieldsModelSerializer(serializers.ModelSerializer):
def __init__(self, *args, **kwargs):
super(DynamicFieldsModelSerializer, self).__init__(*args, **kwargs)
fields = self.context['request'].query_params.get('fields')
if fields:
fields = fields.split(',')
allowed = set(fields)
existing = set(self.fields.keys())
for field_name in existing - allowed:
self.fields.pop(field_name)
And my serializer:
class MySerializer(serializer_mixins.DynamicFieldsModelSerializer, serializers.ModelSerializer):
# fields...
This achieves the goal of not including the fields that the user has not mentioned in fields param of the queryset. But! We end up with actual query to the database that fetches the entire set of fields. This issue, in turn, could be solved by just adding the following code to the view:
class Rfs(ListAPIView):
serializer_class = MySerializer
def get_queryset(self):
qs = ...
fields = request.query_params.get('fields')
if fields:
qs = qs.only(*fields.split(','))
return qs
However, fills like two issues issues here:
non-DRY pattern since we have to repeat ourselves both in the view and the serializer
Sometimes it might be the case that the field name inside the queryset does not correspond exactly to the field name of the model.
So maybe there's some more elegant and Django-native solution for this usecase ?

Answer 1

I am using drf_queryfields
In dependence of your query_params your view will be modified
GET http://127.0.0.1:8000/snippets/
[
{
"id": 1,
"title": "",
"code": "foo = \"bar\"\n",
"linenos": false,
"language": "python",
"style": "friendly"
},
{
"id": 2,
"title": "",
"code": "print \"hello, world\"\n",
"linenos": false,
"language": "python",
"style": "friendly"
}
]
GET http://127.0.0.1:8000/snippets/?fields=id,code
[
{
"id": 1,
"code": "foo = \"bar\"\n",
},
{
"id": 2,
"code": "print \"hello, world\"\n",
}
]
I hope that´s it what you would like to achieve.