I need to access request.user in to_representation function, I tried self.context['request'] but self.context is empty dictionary. Is there anyway to access request.user or any way that I can push this data to this function?
def to_representation(self, obj):
print(self.context)
#output is an empty dictionary {}
UPDATE
class RetrieveView(generics.RetrieveAPIView):
def get(self, request, *args, **kwargs):
uid = kwargs.get('uid')
try:
item = self.model.nodes.get(uid=uid)
except Exception as e:
# error response
serializer = self.serializer_class(item)
return HttpSuccessResponse(SuccessResponse(serializer.data).to_json(), status=status.HTTP_200_OK).send()
class TopicRetrieveView(single_result.RetrieveView):
model = Topic
serializer_class = topic.TopicSerializer
ALL CODES are from django rest framwork Generic views generic.py
serializer_class is attribute we set in class definition or we need to override get_serializer_class function. It will handle in this function:
def get_serializer_class(self):
"""
Return the class to use for the serializer.
Defaults to using `self.serializer_class`.
You may want to override this if you need to provide different
serializations depending on the incoming request.
(Eg. admins get full serialization, others get basic serialization)
"""
assert self.serializer_class is not None, (
"'%s' should either include a `serializer_class` attribute, "
"or override the `get_serializer_class()` method."
% self.__class__.__name__
)
return self.serializer_class
get_serializer_class will used in get_serializer function:
def get_serializer(self, *args, **kwargs):
"""
Return the serializer instance that should be used for validating and
deserializing input, and for serializing output.
"""
serializer_class = self.get_serializer_class()
kwargs['context'] = self.get_serializer_context()
return serializer_class(*args, **kwargs)
and context will fill by get_serializer_context function.
def get_serializer_context(self):
"""
Extra context provided to the serializer class.
"""
return {
'request': self.request,
'format': self.format_kwarg,
'view': self
}
So correct usage is serializer = self.get_serializer(item) because it will use serializer_class for serializing item and fill context with extra information that may be helpful. serializer = self.serializer_class(item) can be used for just serializing item with no more extra information.
Related
I am getting a list of committees by user using a get method in which I am sending a user id but I am getting an error Committee object is not serialize I have serializer created but I dont't know how to serializer the queryset of that particular user id result.
below is my views.py file
def get(self, request, user_id):
get_committees = Committee.objects.filter(user=Profile.objects.get(id=user_id))
data = {
"status": "success",
"data":get_committees
}
res = Response(serializer.data, status=status.HTTP_200_OK)
below is my serializer.py
class MyCommitteesSerializer(serializers.ModelSerializer):
def get_queryset(self, user_id):
my_committees =
Committee.objects.filter(user=Profile.objects.get(id=user_id))
return my_committees
from your code in get method
"data":get_committees
this get_committees is a list and you are trying to return a list but you can only return json, and so you are getting the message.
You can do this in a better way
define your serializer as -
class MyCommitteesSerializer(serializers.ModelSerializer):
class Meta:
model = Committee
fields = ""_all__"
and define your views as -
class MyCommitteesView(generics.ListAPIView):
serializer_class = MyCommitteesSerializer
def get_queryset(self):
queryset = Committee.objects.filter(user=Profile.objects.get(id=self.request.user_id))
return queryset
the serializer will take care of serialization and you can customize this according to your needs.
or else you will have to manually convert your get_committes into json format before returning.
I'm creating a custom create method to process incoming data. It gets validated by a serializer:
# serializers.py:
class ItemVersionSerializer(serializers.ModelSerializer):
item_ver_id = serializers.RegexField(regex='^r\d{2}$', allow_blank=False)
session_id = serializers.RegexField(regex='^s\d{2}$', allow_blank=False)
config = serializers.CharField(min_length=6)
item_ver = serializers.CharField(min_length=6)
(...)
The method itself looks like this:
# views.py:
class ItemVersionViewSet(viewsets.ModelViewSet):
serializer_class = ItemVersionSerializer
lookup_field = 'item_ver_id'
def create(self, request, *args, **kwargs):
data = request.data
model = ItemModel.objects.get(item_id=data["model"])
finished = True if "finished" in data else False
item_version = ItemVersion.objects.create(
model=model,
item_ver_id=data["item_ver_id"],
config=data["config"],
item_ver=data["item_ver"],
session_id=data["session_id"],
finished=finished
)
serializer = ItemVersionSerializer(data=request.data)
if serializer.is_valid():
# item_version.save() # data gets saved even with this line off
return Response(serializer.validated_data)
else:
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
When passing incorrect data, e.g. too short item_ver string, I receive error 400 and this info:
{
"item_ver": [
"Ensure this field has at least 6 characters."
]
}
However, when I correct the data and send it again, I receive IntegrityError: UNIQUE constraint failed: core_itemversion.item_ver_id and looking at the list of instances I can see the new entry saved to the database anyway.
Which method is responsible for saving the data?
Make sure that you validate your serializer BEFORE creating. Like this:
def create(self, request, *args, **kwargs):
serializer = self.get_serializer(data=request.data)
serializer.is_valid(raise_exception=True)
serializer.save()
headers = self.get_success_headers(serializer.data)
return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
As you can see, there is no need for if else when doing serializer.is_valid(), just use raise_exception=True, and the viewset will make sure that the response will be a 400_BAD_REQUEST.
Second, don't do Model.objects.create(), then save. Do ModelSerializer(request.data), and then follow the convention.
Hopefully this makes sense to you, do let me know if you need me to expand.
I currently have the following serializer:
serializers.py
class SurfGroupSerializer(serializers.ModelSerializer):
instructor = SurfInstructorSerializer(many=False)
surfers = SurferSerializer(many=True)
class Meta:
model = SurfGroup
fields = ['uuid', 'instructor', 'date', 'starting_time', 'ending_time', 'surfers']
def create(self, validated_data):
return SurfGroup(**validated_data)
And the following viewset create method (viewset inherited from viewsets.ViewSet as we need some bespoke customization, extra signals and actions etc):
viewsets.py
# Surf Group Create View:
def create(self, request, format=None):
serializer = SurfGroupSerializer(data=request.data)
serializer.is_valid(raise_exception=True)
self.perform_create(serializer)
headers = self.get_success_headers(serializer.data)
response = responses.standardized_json_response(
message='Surf Group Objects Have Been Successfully Created',
data=serializer.data
)
return Response(data=response, status=status.HTTP_201_CREATED, headers=headers)
For the retrieve action, the serializer works well, and we have a nested instructor object in the response. However, I want to perform a create by passing in the instructor uuid attrbiute like (see content in the POST textarea):
Rather than a whole object...I was wondering how we achieve this? Is it best to just have two Serializers, one for performing the create, and one the retrieval?
def create(self, validated_data):
surf_group = SurfGroup(
instructor__uuid=validated_data['instructor'],
)
surf_group.save()
return surf_group
It is good question.
I work with this situations many times and it looks like one option is to have two serializers as you mean: 1 for list/retrieve and 1 for save.
Another option (for me) is to set serializer field input as UUID and output as another serializer data like this:
class SurfGroupSerializer(serializers.ModelSerializer):
instructor = serializers.UUIDField()
surfers = SurferSerializer(many=True, read_only=True)
class Meta:
model = SurfGroup
fields = ['uuid', 'instructor', 'date', 'starting_time', 'ending_time', 'surfers']
# I use this validate method to transform uuid to object which will
# be bypassed to create method for easly save
def validate_instructor(self, instructor_uuid):
try:
return Instructor.objects.get(uuid=instructor_uuid)
except Instructor.DoesNotExist:
# Remember that you dont need to pass field_key: [errors] to ValidationError
# because validate_FIELD will automatically pass field_key for you !
raise ValidationError(['Instructor with the given uuid does not exist.'])
# Overwrite output data
def to_representation(self, instance):
ret = super().to_representation(instance)
ret['instructor'] = SurfInstructorSerializer(instance=instance.instructor).data
return ret
When I try to hit my api/atoms/ endpoint in the browser, I am getting a name undefined error in the views.py file, but it has a base name in urls.
Note: this is a non-model serializer and a ViewSet.
error
...views.py", line 74, in list
instance = atom.values(), many=True)
NameError: name 'atoms' is not defined
views.py
class AtomViewSet(viewsets.ViewSet):
serializer_class = AtomSerializer
def list(self, request):
serializer = AtomSerializer(
instance = atoms.values(), many=True) #<-------------
return Response(serializer.data)
urls.py
# for viewsets in views.py
router = DefaultRouter()
router.register(r'snippets', views.SnippetViewSet)
router.register(r'atoms', views.AtomViewSet, base_name='atoms')
urlpatterns = [
path('', views.api_root),
path('', include(router.urls)),
]
serializer.py
class AtomSerializer(serializers.Serializer):
uid = UniqueIdProperty()
created_at = DateTimeProperty()
updated_at = DateTimeProperty()
charge = IntegerProperty()
mass = FloatProperty()
def create(self, validated_data):
return Atom(id=None, **validated_data)
def update(self, instance, validated_data):
for field, value in validated_data.items():
setattr(instance, field, value)
return instance
This is a basic python NameError exception raised when a local or global name is not found.
The variable atoms is not defined in the list() method or globally, that's why the python interpreter raised the exception.
In your code, you'd write atoms.values(), which forces me to think that you are dealing with a QuerySet, which might be an Atom model.
class AtomViewSet(viewsets.ViewSet):
serializer_class = AtomSerializer
def list(self, request):
serializer = AtomSerializer(instance=Atom.objects.all(), many=True)
return Response(serializer.data)
Note: this is a non-model serializer and a ViewSet.
You are doing create and update operations in your AtomSerializer class, and those are directly connected to the model. I don't see any particular reason that pulls you back from using a ModelSerializer here. Apart from that, you are using the routers, which become a good choice when you deal with the CRUD operations, hence I strongly suggest you use the combination of ModelViewset and ModelSerializer in your code.
In your views.py you did not define atom, you need to define it first before using it or else you will get that error.
class AtomViewSet(viewsets.ViewSet):
serializer_class = AtomSerializer
def list(self, request):
# You need to define the atom first before passing it to your AtomSerializer
atoms = [] # or atom = Atom.objects.all()
serializer = AtomSerializer(
data=atoms,
many=True
)
return Response(serializer.data)
Say I have a simple Django REST Framework view that's extending multiple model classes and serves all the methods in one URL endpoint:
class UserAPIView(RetrieveAPIView, DestroyAPIView, BaseObjectAPIView):
permission_classes = (IsAuthenticated, )
serializer_class = UserSerializer
def get_serializer_class(self, *args, **kwargs):
# return different serializer depending on method??
# return UserUpdateSerializer
return UserViewSerializer
def get(self, request, *args, **kwargs):
"""
Retrieve user details
"""
# ...
return Response(data={'result': "OK"}, status=200)
def delete(self, request, pk):
"""
Delete user
"""
# ...
return Response(data={'result': "OK"}, status=200)
def put(self, request, pk):
"""
Change user
"""
# ...
return Response(data={'result': "OK"}, status=200)
Now I need to use different serializers per method, as my get-method will use different fields than my put-method, example serializers:
class UserViewSerializer(serializers.ModelSerializer):
firstname = serializers.Field(source='firstname')
lastname = serializers.Field(source='lastname')
username = serializers.Field(source='username')
class Meta:
model = User
class UserUpdateSerializer(serializers.ModelSerializer):
firstname = serializers.Field(source='firstname')
lastname = serializers.Field(source='lastname')
class Meta:
model = User
Is it possible to use different serializers for each method in my model based API view?
UPDATE:
I know how to use different serializers inside the methods themselves.
But I need to get the Browsable API generated by Swagger (Django module rest_framework_swagger) to retrieve different serializers for each method.
I can see that loading the API browser page triggers get_serializer_class, but inside that method, I don't know what method Swagger tries to get the serializer for.
How can I get rest_framework_swagger to retrieve different serializers per method?
I think there are at least two ways to achieve this:
You simply set the serializer that you want in each of your methods. Like this:
def get(self, request, *args, **kwargs):
self.serializer_class = UserViewSerializer
# ...
return Response(data={'result': "OK"}, status=200)
You override the get_Serializer_class method. Like this:
def get_serializer_class(self, *args, **kwargs):
if self.request.method == 'POST':
return UserUpdateSerializer
return UserViewSerializer
Hope this helps.
I suppose you could use yaml docstring on each method to override serializers. Like:
def put(self, request, pk):
"""Change user
---
serializer: .serializers.UserUpdateSerializer
"""
# ...
return Response(data={'result': "OK"}, status=200)