Django clone model object with class based createview

Question

I want to prepare a new object but wait for user input to create it:

I've added get_form to this view:

class MyCreateView(CreateView):

    def get_form(self, form_class):
        form = super(MyCreateManView, self).get_form(form_class)
        if self.kwargs['ref']:
            new_item = get_object_or_404(models.MyModel, pk = self.kwargs['ref'])
            new_item.pk = None 
            new_item.note = "Copia di " + new_item.note 
            form =  MyForm(instance = new_item)

    def form_valid(self, form):
        ...

In the method, I read the GET parameter 'ref' and precompile the form fields with that data.

But when I submit the data, the form_valid method is not executed and the new object is not created.

if form.is_valid(): form = form.save(); context = { "form": form, } ; return render(request, "app/template.html", context) — Avinash Raj
– Avinash Raj, Commented Apr 8, 2016 at 9:18
Is it a class based view or a normal view? If it is not a class based view then super(MyCreateManView, self).form_valid(form) doesn't make much sense. Have you got this code from somewhere else and copied in bits and pieces? — AKS
– AKS, Commented Apr 8, 2016 at 9:21

Alasdair · Accepted Answer · 2016-04-08 12:14:38Z

2

When you do,

form  =  MyForm(instance = new_item)

you are not binding the form to any data. This means that the form will never be valid.

I would try overriding get_form_kwargs instead.

def get_form_kwargs(self):
    kwargs = super(MyCreateView, self).get_form_kwargs()
    if self.kwargs['ref']:
        new_item = get_object_or_404(models.MyModel, pk = self.kwargs['ref'])
        ...
        kwargs['instance'] = new_item
    return kwargs

answered Apr 8, 2016 at 12:14

Alasdair

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Exis Zhang · Accepted Answer · 2019-03-11 06:28:11Z

2

The marked answer cannot be correct since I tested it and it will overwrite your existing object!

Use below instead (tested on Django 2.17 )


    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()

        old_item = get_object_or_404(Tutorial, pk=self.kwargs['pk'])
        new_item = deepcopy(old_item)
        new_item.id = None
        kwargs['instance'] = deepcopy(new_item)

        return kwargs

answered Mar 11, 2019 at 6:28

Exis Zhang

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