# forms.py
# ...
class MyForm(forms.ModelForm):
    class Meta:
        model = MyModel

# views.py
# ...
def my_view(request, id):
    instance = get_object_or_404(MyModel, id=id)
    form = MyForm(request.POST or None, instance=instance)
    if form.is_valid():
        form.save()
        return redirect('next_view')
    return render(request, 'my_template.html', {'form': form})