How do I get my Django generic view to work - django

Question

Am I going about this the right way? Having never used 'generic views' I am tying to use Django's generic.UpdateView view. When I 'hit' the 'update' button on the form, I get an invalid form response with message 'Library with this Slide name already exists'
Grateful for any help.
View:
class Slideview(generic.UpdateView):
model = Library
template_name = 'app1/slide_update.html'
fields = ['slide_name', 'reference_value','esd',
'current_mean', 'counts_averaged', 'status']
context_object_name = 'qc_slide'
#def get_queryset(self):
#slide_id = self.kwargs['pk']
#return Library.objects.filter(slide_name=slide_id)
def get_success_url(self):
return reverse('Slideview', args=[self.kwargs['pk']])
def get_context_data(self, **kwargs):
context = super(Slideview, self).get_context_data(**kwargs)
#form = self.get_form(self.get_form_class())
#context['form'] = form
return context
def post(self, request, *args, **kwargs):
print("Im in post")
form = self.get_form(self.get_form_class())
if form.is_valid():
#Code will go here which will query a second model
#perform a series of math calculations and then
#return the updated information
self.object = self.get_object()
self.object.save()
return self.form_valid(form)
else:
print("Form not valid")
self.object = self.get_object()
return self.form_invalid(form)
Model:
class Library(models.Model):
slide_name = models.CharField(max_length=5, primary_key=True)
reference_value = models.DecimalField(max_digits=5, decimal_places=2, default=Decimal(0))
esd = models.DecimalField(max_digits=5, decimal_places=2, default=Decimal(0))
current_mean = models.DecimalField(max_digits=5, decimal_places=2, default=Decimal(0))
counts_averaged = models.IntegerField(default=0)
status = models.CharField(max_length=9)
def __str__(self):
return self.slide_name