Question

I’m creating a form in one page, then in another page I’m trying to pull out the form (populated with the data saved in it already) and would like to make changes to it so that when I save it it overwrites the instance instead of creating another one.

def edit(request):

   a = request.session.get('a',  None)

   if a is None:
       raise Http404('a was not found')

   if request.method == 'POST':
       form = Name_Form(request.POST, instance=a)
       if form.is_valid():
           j = form.save( commit=False )
           j.save()
   else:
       form = Name_Form( instance = a )

This is the code I have for the “editting form” view.. When I open this page the form is successfully prepopulated with all the data. However, when I make changes and save, it does not overwrite the existing instance, instead it creates a new one.

Any ideas?

Answer 1

Have a look here: https://docs.djangoproject.com/en/dev/ref/models/instances/#how-django-knows-to-update-vs-insert
I think this may help you.

Update:
What about trying a more “explicit” way.
Assume, id_of_Name stores only the id or pk of your model which you want to edit (I assume the model is called “Name”). Then just retrieve the id/pk from session to query your db for the model instance. Also try to directly call the save method on the form.

def edit(request):

   id_of_Name = request.session.get('a',  None)

   if id_of_Name is None:
       raise Http404('id_of_Name was not found')
   instance = Name.objects.get(pk=id_of_Name)
   if request.method == 'POST':
       form = Name_Form(request.POST, instance=instance)
       if form.is_valid():
           form.save()
   else:
       form = Name_Form( instance = instance )