title: Editing django-rest-framework serializer object before save
body: <p>I want to edit a <code>django-rest-framwork</code> serializer object before it is saved. This is how I currently do it -   </p>
  
  <pre><code>def upload(request):
      if request.method == 'POST':
          form = ImageForm(request.POST, request.FILES)
          if form.is_valid(): # All validation rules pass
               obj = form.save(commit=False)
               obj.user_id = 15
               obj.save()
  </code></pre>
  
  <p>How can I do it with a <code>django-rest-framework</code> serializer object?</p>
  
  <pre><code>@api_view(['POST','GET'])
  def upload_serializers(request):
      if request.method == 'POST':
           serializer = FilesSerializer(data=request.DATA, files=request.FILES)
           if serializer.is_valid():
                serializer.save()
  </code></pre>