Meta fields are not filtered out dynamically

[SafaAlfulaij]

Description of the Bug Report

DRF supports dynamically changing the fields returned per request. This works well (despite the performance issues, etc)

Meta fields though does not get filtered based on this properly. If the field is excluded, it will be rendered with a null value (since the actual value is not provided by DRF).

My expectation is that it does not render at all.

Culprits:

django-rest-framework-json-api/rest_framework_json_api/serializers.py

Lines 305 to 318 in e9ca8d9

	def get_field_names(self, declared_fields, info):
	"""
	We override the parent to omit explicity defined meta fields (such
	as SerializerMethodFields) from the list of declared fields
	"""
	meta_fields = getattr(self.Meta, "meta_fields", [])
	declared = OrderedDict()
	for field_name in set(declared_fields.keys()):
	field = declared_fields[field_name]
	if field_name not in meta_fields:
	declared[field_name] = field
	fields = super().get_field_names(declared, info)
	return list(fields) + list(getattr(self.Meta, "meta_fields", list()))

django-rest-framework-json-api/rest_framework_json_api/renderers.py

Lines 411 to 425 in e9ca8d9

	@classmethod
	def extract_meta(cls, serializer, resource):
	"""
	Gathers the data from serializer fields specified in meta_fields and adds it to
	the meta object.
	"""
	if hasattr(serializer, "child"):
	meta = getattr(serializer.child, "Meta", None)
	else:
	meta = getattr(serializer, "Meta", None)
	meta_fields = getattr(meta, "meta_fields", [])
	data = OrderedDict()
	for field_name in meta_fields:
	data.update({field_name: resource.get(field_name)})
	return data

Checklist

• Certain that this is a bug (if unsure or you have a question use discussions instead)
• Code snippet or unit test added to reproduce bug

[sliverc]

As I see it is this basically the same bug as described in #332 as the sparse fields mixin uses this feature to dynamically change the fields.

[SafaAlfulaij]

Indeed. Closing this then.