Dynamically include or exclude Serializer class fields - django

Question

In my User profile model I've included a show_email field explicitly. So, to add this feature to my API, the UserSerializer class looks like this:
class UserSerializer(serializers.ModelSerializer):
email = serializers.SerializerMethodField('show_email')
def show_email(self, user):
return user.email if user.show_email else None
class Meta:
model = django.contrib.auth.get_user_model()
fields = ("username", "first_name", "last_name", "email")
But I don't really like it. I think it would be a lot cleaner if the field email would be completely excluded from the serializer output it show_email is False, instead showing that ugly "email": null thing.
How could I do that?

Answer 1

You could do this in your API view by overriding the method returning the response, i.e. the "verb" of the API view. For example, in a ListAPIView you would override get():
class UserList(generics.ListAPIView):
model = django.contrib.auth.get_user_model()
serializer_class = UserSerializer
def get(self, request, *args, **kwargs):
response = super(UserList, self).get(request, *args, **kwargs)
for result in response.data['results']:
if result['email'] is None:
result.pop('email')
return response
You would probably want to add some more checking for attributes, but that's the gist of how it could be done. Also, I would add that removing fields from some results may cause issues for the consuming application if it expects them to be present for all records.

Answer 2

This answer comes late but for future google searches: there is an example in the documentation about Dynamically modifying fields.
So, by passing an argument to the serializer, you control whether or not a field is processed:
serializer = MyPostSerializer(posts, show_email=permissions)
and then in the init function in the serializer you can do something like:
class MyPostSerializer(serializers.ModelSerializer):
def __init__(self, *args, **kwargs):
show_email = kwargs.pop('show_email', None)
# Instantiate the superclass normally
super(DeviceSerializer, self).__init__(*args, **kwargs)
if not show_email:
self.fields.pop("show_email")
Now the show_email field will be ignored by the serializer.

Answer 3

You could override restore_fields method on serializer. Here in restore_fields method you can modify list of fields - serializer.fields - pop, push or modify any of the fields.
eg: Field workspace is read_only when action is not 'create'
class MyPostSerializer(ModelSerializer):
def restore_fields(self, data, files):
if (self.context.get('view').action != 'create'):
self.fields.get('workspace').read_only=True
return super(MyPostSerializer, self).restore_fields(data, files)
class Meta:
model = MyPost
fields = ('id', 'name', 'workspace')

Answer 4

This might be of help...
To dynamically include or exclude a field in an API request, the modification of
#stackedUser's response below should do:
class AirtimePurchaseSerializer(serializers.Serializer):
def __init__(self, *args, **kwargs):
try:
phone = kwargs['data']['res_phone_number']
except KeyError:
phone = None
# Instantiate the superclass normally
super(AirtimePurchaseSerializer, self).__init__(*args, **kwargs)
if not phone:
self.fields.pop("res_phone_number")
res_phone_number = serializers.CharField(max_length=16, allow_null=False)