Django Update unique modelform field - django

Question

I have created small stock web app.
I created a stock model with unique part_number field. In my update template I send all item information to be displayed. Then I get an error in the part_number field that it is already there.
How can I avoid this validation for that part_number only?
I mean for same part_number suppose validation will not work. But if I modified to another part_number that already exists I get an error that it's being duplicated.
Model:
class Stock(models.Model):
part_number = models.CharField(max_length=30, blank=False, unique=True)
part_name = models.CharField(max_length=70)
quantity = models.IntegerField(blank=False)
location = models.CharField(max_length=3, blank=True)
model = models.CharField(max_length=40, blank=True, null=True, default="")
min_quantity = models.IntegerField(unique=False, blank=True, default=0)
max_quantity = models.IntegerField(unique=False, blank=True, default=0)
class Meta:
ordering = ['part_number']
def clean(self):
self.part_number = self.part_number.upper()
def __str__(self):
return self.part_number
Form.py:
class StockUpdateModelForm(forms.ModelForm):
class Meta:
model = models.Stock
fields = ['part_name', 'quantity', 'location','part_number']
views.py:
def stock_update_form_view(request, part_id):
item = Stock.objects.get(id=part_id)
item_id = Stock.objects.get(id=part_id).pk
form = StockUpdateModelForm({
'part_number' : item.part_number,
'part_name' : item.part_name,
'quantity' : item.quantity,
'location' : item.location
})
if request.method == 'POST':
form = StockUpdateModelForm(request.POST)
if form.is_valid():
s = Stock.objects.get(pk=item_id)
s.part_name = form.cleaned_data['part_name']
s.part_number = form.cleaned_data['part_number']
s.quantity = form.cleaned_data['quantity']
s.location = form.cleaned_data['location']
print("form is valid")
s.save()
return redirect('/stock/')
return render(request, 'stock/stock_update.html', {'form': form, 'pn': item.part_number})
html:
<form class="bg-light shadow" method="POST">
<div style="margin-left:10%; margin-top:30px">
<h4>Part Number : {{ pn }}</h4>
</div>
<hr style="width:100%">
{% csrf_token %}
<div class="row" style="margin-left:30px; margin-top:40px ">
<div class="col-sm-4" style="margin-left:6%">
{{ form.part_name|as_crispy_field }}
</div>
<div class="col-sm-4" style="margin-left:15%">
{{ form.part_number|as_crispy_field }}
</div>
<div class="col-sm-4" style="margin-left:6%">
{{ form.quantity|as_crispy_field }}
</div>
<div class="col-sm-4" style="margin-left:15%">
{{ form.location|as_crispy_field }}
</div>
<div class="col-sm-4" style="height: 100px; margin-top:30px ; margin-left:6%">
<hr style="width:100%">
<input class="btn btn-primary" type="submit" value="Save"
style="width: 150px;">
</div>
</div>
</form>

Answer 1

try this
if request.method == 'POST':
form = StockUpdateModelForm(request.POST, instance=item)
if form.is_valid():
form.save()