Make Django REST API accept a list

Question

I'm working on a functionality where I need to be able to post a list consisting of properties to the API. A property has a name, value and unit. Now I have two questions:

1. How exactly should my list look for the API to accept it as a correct list from the get go? Should I parse the list as Objects? Or is a plain list fine?
2. I am using the Django REST framework and I have made the API using this tutorial (works perfectly). But how do I make Django accept multiple objects/a list? I have read that it is as simple as adding many = True to where you instantiate the serializer, which I do here:

(for some reason the code won't format unless I put text here)

class PropertyViewSet(viewsets.ModelViewSet):  
    queryset = Property.objects.all()  
    serializer_class = PropertySerializer

So I tried doing serializer = PropertySerializer(queryset, many=True), which broke the API view. So I think I have to create a new serializer and view just for this (am I right)? But how do I make sure that my API knows which one to use at the right time?

If anyone could clarify this that would be great, thanks.

Answer 1

If you need to create the object, here is how I did it:

# Mixin that allows to create multiple objects from lists.
class CreateListModelMixin(object):
    def get_serializer(self, *args, **kwargs):
        """ if an array is passed, set serializer to many """
        if isinstance(kwargs.get('data', {}), list):
            kwargs['many'] = True
        return super(CreateListModelMixin, self).get_serializer(*args, **kwargs)

And then in the view that you would like to use it in just do:

class PropertyCreateView(CreateListModelMixin, generics.CreateAPIView):
    serializer_class = PropertySerializer
    permission_classes = (IsAuthenticated, )

And that's already it (make sure to put in the mixin as an argument BEFORE the view; like I did it).

Now the body of your postrequest would look like this:

{
  [
    {
      "name": "<some_name>"
      "value": "<some_value>"
      "unit": "<some_unit>"
    },
    {
      "name": "<some_name>"
      "value": "<some_value>"
      "unit": "<some_unit>"
    },
    {
      "name": "<some_name>"
      "value": "<some_value>"
      "unit": "<some_unit>"
    },
    ...
  ]
}

The cool thing about it, this way you can also just post a single object like this:

{
  "name": "<some_name>"
  "value": "<some_value>"
  "unit": "<some_unit>"
}

I hope this helps! :)

Answer 2

ModelViewSet class provides a create() method which only allows you to create one object at a time. see docs

if you want to POST a list of objects and insert each object to the database, you would have to create a custom view. for e.g.

from rest_framework.decorators import api_view
from django.shortcuts import redirect
from .models import MyModel

@api_view(['POST'])
def insert_list(request):
    if request.method == 'POST':
        for obj in request.POST['list']: #assuming you are posting a 'list' of objects
            MyModel.objects.create(name=obj.name, value=obj.value, unit=obj.unit)
    return redirect('url of MyObject List View')

to use your custom APIview alongside the viewset, just add your custom APIview to a different url not used by the viewset url e.g. if your viewset uses r'^myModel/$' then use r'^myModel/insert_list/$' for the createlist custom APIview