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Django Rest Framework - Dynamic Fields
# How to display only interesting fields for a Django Rest Framework API
# /?fields=field1,field2,field3
from rest_framework import serializers, pagination
class DynamicFieldsModelSerializer(serializers.ModelSerializer):
"""
A ModelSerializer that takes an additional `fields` argument that
controls which fields should be displayed.
See:
http://tomchristie.github.io/rest-framework-2-docs/api-guide/serializers
"""
def __init__(self, *args, **kwargs):
# Don't pass the 'fields' arg up to the superclass
fields = kwargs.pop('fields', None)
# Instantiate the superclass normally
super(DynamicFieldsModelSerializer, self).__init__(*args, **kwargs)
if fields:
# Drop any fields that are not specified in the `fields` argument.
allowed = set(fields)
existing = set(self.fields.keys())
for field_name in existing - allowed:
self.fields.pop(field_name)
class DynamicFieldsPaginationSerializer(pagination.BasePaginationSerializer):
"""
A dynamic fields implementation of a pagination serializer.
"""
count = serializers.Field(source='paginator.count')
next = pagination.NextPageField(source='*')
previous = pagination.PreviousPageField(source='*')
def __init__(self, *args, **kwargs):
"""
Override init to add in the object serializer field on-the-fly.
"""
fields = kwargs.pop('fields', None)
super(pagination.BasePaginationSerializer, self).__init__(*args, **kwargs)
results_field = self.results_field
object_serializer = self.opts.object_serializer_class
if 'context' in kwargs:
context_kwarg = {'context': kwargs['context']}
else:
context_kwarg = {}
if fields:
context_kwarg.update({'fields': fields})
self.fields[results_field] = object_serializer(source='object_list',
many=True,
**context_kwarg)
class DynamicFields(object):
"""A mixins that allows the query builder to display certain fields"""
def get_fields_to_display(self):
fields = self.request.GET.get('fields', None)
return fields.split(',') if fields else None
def get_serializer(self, instance=None, data=None, files=None, many=False,
partial=False, allow_add_remove=False):
"""
Return the serializer instance that should be used for validating and
deserializing input, and for serializing output.
"""
serializer_class = self.get_serializer_class()
context = self.get_serializer_context()
fields = self.get_fields_to_display()
return serializer_class(instance, data=data, files=files,
many=many, partial=partial,
allow_add_remove=allow_add_remove,
context=context, fields=fields)
def get_pagination_serializer(self, page):
"""
Return a serializer instance to use with paginated data.
"""
class SerializerClass(self.pagination_serializer_class):
class Meta:
object_serializer_class = self.get_serializer_class()
pagination_serializer_class = SerializerClass
context = self.get_serializer_context()
fields = self.get_fields_to_display()
return pagination_serializer_class(instance=page, context=context, fields=fields)
# Howto
# Set the pagination serializer setting
REST_FRAMEWORK = {
# [...]
'DEFAULT_PAGINATION_SERIALIZER_CLASS': 'DynamicFieldsPaginationSerializer',
}
# Inherit your serializers with DynamicFieldsModelSerializer
class MyPonySerializer(DynamicFieldsModelSerializer):
# [...]
# Make your API Views with mixin
class MyPonyList(DynamicFields, generics.ListAPIView):
# [...]
# Enjoy !
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