title: Use CreateAPIView when having all model fields implicit (django-rest-framework)
body: <p>I have the following scenario:</p>
  
  <p>I have a FooModel, a FooModelSerializer serializer and a AddFooObject view which inherits the CreateAPIView generic view in which I would like to add a record to the DB. My problem is that all the fields from the FooModel are implicit (information like the current time, system information, etc.). I tried solving this by adding them inside the <code>pre_save</code> method, but the flow does not get there because when it receives the request, it looks for the fields existing the model and it does not find them, thus returning <code>HTTP_400_BAD_REQUEST</code> and <code>"foo_field": ["This field is required."]</code>. </p>
  
  <p>Is there a chance of using the generic view, exclude all the fields from the model and add them only in the <code>pre_save</code> method or should I use normal views?</p>
  
  <p>Thanks in advance! </p>