python - Pass extra arguments to Serializer Class in Django Rest Framework

84
votes

I want to pass some arguments to DRF Serializer class from Viewset, so for I have tried this:

class OneZeroSerializer(rest_serializer.ModelSerializer):

    def __init__(self, *args, **kwargs):
        print args # show values that passed

    location = rest_serializer.SerializerMethodField('get_alternate_name')

    def get_alternate_name(self, obj):
        return ''


    class Meta:
        model = OneZero

        fields = ('id', 'location')

Views

class OneZeroViewSet(viewsets.ModelViewSet):

   serializer_class = OneZeroSerializer(realpart=1)
   #serializer_class = OneZeroSerializer

   queryset = OneZero.objects.all()

Basically I want to pass some value based on querystring from views to Serializer class and then these will be allocate to fields.

These fields are not include in Model in fact dynamically created fields.

Same case in this question stackoverflow, but I cannot understand the answer.

Can anyone help me in this case or suggest me better options.

5
pythondjangorestdjango-rest-framework
@PauloScardine can you provide me simple example or any link where i can get help? I am new to django thats why can't getting your words. - Shoaib Ijaz
The answer to the question you refer is right, go read the documentation on the get_serializer method and override it to return a custom instance of the serializer. - Paulo Scardine
possible duplicate of Dynamically modifying serializer fields in Django Rest Framework - Paulo Scardine
I have also mentioned this question as reference, but there is no detail that can help me - Shoaib Ijaz
I have read the documentation but i cannot found any example where extra parameters are passed. there are just example how to use different serialize class. that why i posted question here - Shoaib Ijaz

5 Answers

114
votes

It's very easy with "context" arg for "ModelSerializer" constructor.

For example:

in view:

my_objects = MyModelSerializer(
    input_collection, 
    many=True, 
    context={'user_id': request.user.id}
).data

in serializers:

class MyModelSerializer(serializers.ModelSerializer):
...

    is_my_object = serializers.SerializerMethodField('_is_my_find')
...

    def _is_my_find(self, obj):
        user_id = self.context.get("user_id")
        if user_id:
            return user_id in obj.my_objects.values_list("user_id", flat=True)
        return False
...

so you can use "self.context" for getting extra params.

Reference

33
votes

You could in the YourView override get_serializer_context method like that:

class YourView(GenericAPIView):

    def get_serializer_context(self):
        context = super().get_serializer_context()
        context["customer_id"] = self.kwargs['customer_id']
        context["query_params"] = self.request.query_params
        return context

or like that:

class YourView(GenericAPIView):
    def post(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)

        serializer.context["customer_id"] = request.user.id
        serializer.context["query_params"] = request.query_params

        serializer.is_valid(raise_exception=True)
        ...

and anywhere in your serializer you can get it. For example in a custom method:

class YourSerializer(ModelSerializer):
    def get_alternate_name(self, obj):
        customer_id = self.context["customer_id"]
        query_params = self.context["query_params"]
        ...
28
votes

To fulfill the answer of redcyb - consider using in your view the get_serializer_context method from GenericAPIView, like this:

def get_serializer_context(self):
    return {'user': self.request.user.email}
10
votes

A old code I wrote, that might be helpful- done to filter nested serializer:

class MySerializer(serializers.ModelSerializer):

    field3  = serializers.SerializerMethodField('get_filtered_data')

    def get_filtered_data(self, obj):
        param_value = self.context['request'].QUERY_PARAMS.get('Param_name', None)
        if param_value is not None:
            try:
                data = Other_model.objects.get(pk_field=obj, filter_field=param_value)
            except:
                return None
            serializer = OtherSerializer(data)
            return serializer.data
        else:
            print "Error stuff"

    class Meta:
        model = Model_name
        fields = ('filed1', 'field2', 'field3')

How to override get_serializer_class:

class ViewName(generics.ListAPIView):

    def get_serializer_class(self):
        param_value = self.context['request'].QUERY_PARAMS.get('Param_name', None)
        if param_value is not None:
            return Serializer1
        else:
            return Serializer2

    def get_queryset(self):
       .....

Hope this helps people looking for this.

0
votes

These answers are far to complicated; If you have any sort of authentication then add this property to your serializer and call it to access the user sending the request.

class BaseSerializer(serializers.ModelSerializer):

@property
def sent_from_user(self):
    return self.context['request'].user