Django REST Serializer uses wrong Model for serialization - django

Question

Problem:
My serializer uses the wrong Model for serialization. I expected that the serializer uses my ProfileInfo model but it does not. It uses the User model. They have an OneToOneRelationship. I do not know why because I defined in the meta that the serializer should use the ProfileInfo model.
So when I try to serialize the username with -> username=serializers.Field(source='user.username') Django shows this error:
'User' object has no attribute 'user'.
Can you please explain to me why the wrong model is used ? Thank you for your help.
Serializers:
class ProfileInfoSerializer(serializers.ModelSerializer):
image = serializers.SerializerMethodField()
socialMediaLinks = serializers.SerializerMethodField("get_social_media_links")
username = serializers.Field(source='user.username')
class Meta:
model = ProfileInfo
fields = ['username', 'description', 'image', 'socialMediaLinks']
def get_image(self, obj):
request = self.context.get('request')
photo_url = obj.image.url
return request.build_absolute_uri(photo_url)
class UserInfoSerializer(serializers.ModelSerializer):
user = ProfileInfoSerializer()
wingman = ProfileInfoSerializer()
clan = ClanSerializer()
class Meta:
model = ProfileInfo
fields = ['user', 'clan', 'wingman']
Model:
class ProfileInfo(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE, primary_key=True)
wingman = models.OneToOneField(User, on_delete=None, related_name="wingman", null=True)
clan = models.ForeignKey(Clan, on_delete=None)
image = models.ImageField(upload_to="", default="", null=True)
description = models.CharField(max_length=5000, null=True)
Api:
class ProfileInfoApi(APIView):
def get(self, request, id):
profileInfo = ProfileInfo.objects.get(pk=id)
serializer = UserInfoSerializer(profileInfo, context={'request': request})
return Response(serializer.data)
Traceback:
Internal Server Error: /api/profileInfo/1/
Traceback (most recent call last):
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\django\core\handlers\exception.py", line 35, in inner
response = get_response(request)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\django\core\handlers\base.py", line 128, in _get_response
response = self.process_exception_by_middleware(e, request)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\django\core\handlers\base.py", line 126, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\django\views\decorators\csrf.py", line 54, in wrapped_view
return view_func(*args, **kwargs)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\django\views\generic\base.py", line 69, in view
return self.dispatch(request, *args, **kwargs)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\views.py", line 483, in dispatch
response = self.handle_exception(exc)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\views.py", line 443, in handle_exception
self.raise_uncaught_exception(exc)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\views.py", line 480, in dispatch
response = handler(request, *args, **kwargs)
File "C:\_sources\Gamingplattform\Backend\gamingplattform\profileInfo\api.py", line 18, in get
return Response(serializer.data)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\serializers.py", line 560, in data
ret = super(Serializer, self).data
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\serializers.py", line 262, in data
self._data = self.to_representation(self.instance)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\serializers.py", line 527, in to_representation
ret[field.field_name] = field.to_representation(attribute)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\fields.py", line 570, in to_representation
field_name=self.field_name,
NotImplementedError: Field.to_representation() must be implemented for field username. If you do not need to support write operations you probably want to subclass `ReadOnlyField` instead.
Internal Server Error: /api/profileInfo/getFriends/1/
Traceback (most recent call last):
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\fields.py", line 441, in get_attribute
return get_attribute(instance, self.source_attrs)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\fields.py", line 100, in get_attribute
instance = getattr(instance, attr)
AttributeError: 'User' object has no attribute 'user'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\django\core\handlers\exception.py", line 35, in inner
response = get_response(request)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\django\core\handlers\base.py", line 128, in _get_response
response = self.process_exception_by_middleware(e, request)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\django\core\handlers\base.py", line 126, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\django\views\decorators\csrf.py", line 54, in wrapped_view
return view_func(*args, **kwargs)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\django\views\generic\base.py", line 69, in view
return self.dispatch(request, *args, **kwargs)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\views.py", line 483, in dispatch
response = self.handle_exception(exc)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\views.py", line 443, in handle_exception
self.raise_uncaught_exception(exc)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\views.py", line 480, in dispatch
response = handler(request, *args, **kwargs)
File "C:\_sources\Gamingplattform\Backend\gamingplattform\profileInfo\api.py", line 36, in get
return Response(serializer.data)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\serializers.py", line 765, in data
ret = super(ListSerializer, self).data
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\serializers.py", line 262, in data
self._data = self.to_representation(self.instance)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\serializers.py", line 683, in to_representation
self.child.to_representation(item) for item in iterable
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\serializers.py", line 683, in <listcomp>
self.child.to_representation(item) for item in iterable
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\serializers.py", line 527, in to_representation
ret[field.field_name] = field.to_representation(attribute)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\serializers.py", line 514, in to_representation
attribute = field.get_attribute(instance)
File "C:\Users\Aaron Visang\AppData\Local\Programs\Python\Python36\lib\site-packages\rest_framework\fields.py", line 462, in get_attribute
raise type(exc)(msg)
AttributeError: Got AttributeError when attempting to get a value for field `username` on serializer `ProfileInfoSerializer`.
The serializer field might be named incorrectly and not match any attribute or key on the `User` instance.
Original exception text was: 'User' object has no attribute 'user'.

Answer 1

You are trying to serialize ProfileInfo instances with UserInfoSerializer serializer, which is not possible. So
Change
serializer = UserInfoSerializer(profileInfo, context={'request': request})
to
serializer = ProfileInfoSerializer(profileInfo, context={'request': request})
Hence your view be like,
class ProfileInfoApi(APIView):
def get(self, request, id):
profileInfo = ProfileInfo.objects.get(pk=id)
serializer = ProfileInfoSerializer(profileInfo, context={'request': request})
return Response(serializer.data)
UPDATE-1It's NotImplementedError,You shouldn't use serializer.Field class unless you need to inherrit. So change
username = serializers.Field(source='user.username')
to
username = serializers.CharField(source='user.username')<br>
Apart from this update, I would like to inform that, you are defined one line as , socialMediaLinks = serializers.SerializerMethodField("get_social_media_links") But, there is no method named get_social_media_links. It will raise some error, sureSo the ProfileInfoSerializer should be as below
class ProfileInfoSerializer(serializers.ModelSerializer):
image = serializers.SerializerMethodField()
socialMediaLinks = serializers.SerializerMethodField("get_social_media_links")
username = serializers.CharField(source='user.username')
class Meta:
model = ProfileInfo
fields = ['username', 'description', 'image', 'socialMediaLinks']
def get_image(self, obj):
request = self.context.get('request')
photo_url = obj.image.url
return request.build_absolute_uri(photo_url)
def get_social_media_links(self, model):
return "some data"