Object update by PATCH for Django REST Framework-CodePudding

I am using viewsets.ModelViewSet

from rest_framework import viewsets

class ProjectViewSet(viewsets.ModelViewSet):
    serializer_class = s.ProjectSerializer   
    queryset = m.Project.objects.all()

    def patch(self,request,*args,**kwargs):
      instance = self.get_object()
      serializer = self.get_serializer(instance,data = request.data)
      if serializer.is_valid():
          self.perform_update(serializer)
          return Response(serializer.data)
      return Response()

Then I test to update the object via django restframework UI.

Then this error occurs.

My basic idea that changing object data via PATCH is correct?

How can I update the data via Django REST Framework

Expected view ProjectViewSet to be called with a URL keyword argument named "pk". Fix your URL conf, or set the `.lookup_field` attribute on the view correctly.

CodePudding user response：

First, the problem is directly related to URL setup, in any case I would suggest using DRF routers:

from django.urls import path, include
from .views import ProjectViewSet
from rest_framework.routers import DefaultRouter

router = DefaultRouter()
router.register(r'projects', ProjectViewSet)

urlpatterns = [
    path('api/', include(router.urls)),
]

Secondly, the actions provided by ModelViewSet are .list(), .retrieve(), .create(), .update(), .partial_update(), and .destroy().

The action related to PATCH is partial_update, so:

class ProjectViewSet(ModelViewSet):
    serializer_class = ProjectSerializer   
    queryset = Project.objects.all()

    def partial_update(self, request, *args, **kwargs):
        partial = True
        instance = self.get_object()
        serializer = self.get_serializer(instance, data=request.data, partial=partial)
        serializer.is_valid(raise_exception=True)
        self.perform_update(serializer)

        return Response(serializer.data)

Original code of UpdateModelMixin

.partial_update:

def partial_update(self, request, *args, **kwargs):
    kwargs['partial'] = True
    return self.update(request, *args, **kwargs)

As you can see it still calls .update which does almost exactly the same:

def update(self, request, *args, **kwargs):
    partial = kwargs.pop('partial', False)
    instance = self.get_object()
    serializer = self.get_serializer(instance, data=request.data, partial=partial)
    serializer.is_valid(raise_exception=True)
    self.perform_update(serializer)

    if getattr(instance, '_prefetched_objects_cache', None):
        # If 'prefetch_related' has been applied to a queryset, we need to
        # forcibly invalidate the prefetch cache on the instance.
        instance._prefetched_objects_cache = {}

    return Response(serializer.data)