Current User inside nested serializer - django

Question

I'm using Django Rest Framework 3.3.2 with Django 1.9.1
I have 2 serializers and I use one of them inside the other one.
class VideoSerializer(serializers.ModelSerializer):
current_username = serializers.SerializerMethodField()
is_deletable = serializers.SerializerMethodField()
tagged_users = EachUserSerializer(many=True, read_only=True)
print current_username
comments = CommentSerializer(many=True, read_only=True, context={'current_username': current_username})
place_taken = PlaceLimitedSerializer()
owner_user = EachUserSerializer()
class Meta:
model = Video
fields = ('tagged_users', 'comments', 'place_taken', 'video_id', 'video_url', 'like_count', 'caption', 'date',
'category', 'owner_user', 'current_username', 'is_deletable', )
def get_current_username(self, obj):
self.current_username = self.context['request'].user.username
return self.context['request'].user.username
def get_is_deletable(self, obj):
return obj.is_deletable_by(self.current_username)
class CommentSerializer(serializers.ModelSerializer):
current_username = serializers.SerializerMethodField()
is_deletable = serializers.SerializerMethodField()
is_editable = serializers.SerializerMethodField()
def get_current_username(self, obj):
self.current_username = self.context['current_username']
return self.current_username
def get_is_deletable(self, obj):
return obj.is_deletable(self.current_username)
def get_is_editable(self, obj):
return obj.is_editable(self.current_username)
class Meta:
model = Comment
fields = ('comment', 'username', 'comment_id', 'date', 'current_username', 'is_editable', 'is_deletable',)
My question is that I need current user's username in serializers. I managed to do that in VideoSerializer by setting a context in view like this.
class get_video(APIView):
def get(self, request):
video_id = str(request.query_params.get('video_id'))
if Video.objects.all().filter(video_id=video_id).exists():
video = Video.objects.get(video_id=video_id)
serializer = VideoSerializer(video, context={"request": request})
return JsonResponse(serializer.data)
else:
return JsonResponse({"result": "no_video"})
In VideoSerializer, I tried to set context and I want to pass 'current_user' to the CommentSerializer but it gives this error.
Internal Server Error: /video/get_video/
Traceback (most recent call last):
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/django/core/handlers/base.py", line 149, in get_response
response = self.process_exception_by_middleware(e, request)
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/django/core/handlers/base.py", line 147, in get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
return view_func(*args, **kwargs)
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/django/views/generic/base.py", line 68, in view
return self.dispatch(request, *args, **kwargs)
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/rest_framework/views.py", line 466, in dispatch
response = self.handle_exception(exc)
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/rest_framework/views.py", line 463, in dispatch
response = handler(request, *args, **kwargs)
File "/Users/mcagataybarin/molocate-dev/molocate_eb/video/views.py", line 96, in get
return JsonResponse(serializer.data)
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/rest_framework/serializers.py", line 503, in data
ret = super(Serializer, self).data
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/rest_framework/serializers.py", line 239, in data
self._data = self.to_representation(self.instance)
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/rest_framework/serializers.py", line 472, in to_representation
ret[field.field_name] = field.to_representation(attribute)
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/rest_framework/serializers.py", line 614, in to_representation
self.child.to_representation(item) for item in iterable
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/rest_framework/serializers.py", line 472, in to_representation
ret[field.field_name] = field.to_representation(attribute)
File "/Users/mcagataybarin/molocate-dev/env/lib/python2.7/site-packages/rest_framework/fields.py", line 1645, in to_representation
return method(value)
File "/Users/mcagataybarin/molocate-dev/molocate_eb/video/serializers.py", line 13, in get_current_username
self.current_username = self.context['current_username']
KeyError: 'current_username'
How can I fix that ? I checked the DRF documentation and also checked the stackoverflow but couldn't find the right answer. I'd appreciate if you help.

Answer 1

The context is available for anything that is under the top serializer - i.e. applies to Serializers and Fields as well.
Therefore in the CommentSerializer you should have:
self.current_username = self.context['request'].user.username

Answer 2

After a lot of google search, I fixed the problem like this.
class VideoSerializer(serializers.ModelSerializer):
current_username = serializers.SerializerMethodField()
is_deletable = serializers.SerializerMethodField()
tagged_users = EachUserSerializer(many=True, read_only=True)
comments = serializers.SerializerMethodField()
place_taken = PlaceLimitedSerializer()
owner_user = EachUserSerializer()
class Meta:
model = Video
field = ('tagged_users', 'comments', 'place_taken', 'video_id', 'video_url', 'like_count', 'caption', 'date',
'category', 'owner_user', 'is_deletable', )
def get_comments(self, obj):
serializer_context = {'current_username': self.current_username}
serializer = CommentSerializer(obj.comments, many=True, read_only=True, context=serializer_context)
return serializer.data
def get_current_username(self, obj):
self.current_username = self.context['request'].user.username
return self.context['request'].user.username
def get_is_deletable(self, obj):
return obj.is_deletable_by(self.current_username)
class CommentSerializer(serializers.ModelSerializer):
current_username = serializers.SerializerMethodField()
is_deletable = serializers.SerializerMethodField()
is_editable = serializers.SerializerMethodField()
def get_current_username(self, obj):
self.current_username = self.context.get('current_username')
return self.context.get('current_username')
def get_is_deletable(self, obj):
return obj.is_deletable(self.current_username)
def get_is_editable(self, obj):
return obj.is_editable(self.current_username)
class Meta:
model = Comment
fields = ('comment', 'username', 'comment_id', 'date', 'current_username', 'is_editable', 'is_deletable',)
I serialized the nested serialization inside SerializerMethodField and I've sent the current_username that I extract from context to the nester serializer's context. After doing this problem solved and it works :)