Update a particular field in django forms and not be able to edit the others - django-models

Question

I am trying to create a expense claim app, i have created a form where a user can claim a expense ,when the admin Logs in the following webpage in the picture appears and the webpages iterates all the claims that have claim_status == Null, i want the admin to be able to accept or reject the claim from the dropdown and it to update the value for that object in the database and webpage to refresh and that claim showing no more
I have given a initial value of Null for the ExpenseClaim model and when user fills the expense claim form he cannot see the claim_status field
please see my models
class ExpenseClaim(models.Model):
reference_number = models.AutoField(primary_key=True)
employee_name = models.CharField(max_length=150)
employee_ID = models.CharField(max_length=150)
claim_initiating_date = models.DateTimeField(auto_now=True)
invoice_date = models.DateField()
invoice_location = models.CharField(max_length=150)
biller_name = models.CharField(max_length=150)
invoice_category = models.CharField(max_length=150)
price = models.DecimalField(decimal_places=2, max_digits=10, null=False , default=0.00)
GST = models.DecimalField(decimal_places=2 ,max_digits=10, null=False , default=0.00)
CGST = models.DecimalField(decimal_places=2 ,max_digits=10, null=False , default=0.00)
IGST = models.DecimalField(decimal_places=2, max_digits=10, null=False , default=0.00)
Total_amount = models.DecimalField(decimal_places=2 ,max_digits=10, null=False , default=0.00)
mode_of_payement = models.CharField(max_length=20)
Payment_reference = models.BooleanField()
invoice = models.FileField()
claim_status = models.CharField(default=None , max_length=10)
payment_status = models.CharField(default= None , max_length=10)
Following is my models field i tried to create a new form but that just creates a new object in the database i want to update the existing one
invoice_category_choices =[
('food',"food"),
('travel',"travel"),
('accodmodation',"accomodation"),
('fuel',"fuel"),
# ('others',"others"),
]
claim_status_choices = [
('accepted' , 'accepted'),
('rejected' , 'rejected')
]
payment_status_choices =[
('paid' , 'paid'),
('notpaid' , 'notpaid')
]
class ExpenseClaimForm(forms.ModelForm):
class Meta:
model = ExpenseClaim
exclude = [
"employee_name",
"employee_ID",
"claim_status",
"payment_status"
]
widgets = {
'invoice_date': forms.DateInput(format=('%m/%d/%Y'), attrs={'class':'form-control', 'placeholder':'Select a date', 'type':'date'}),
'invoice_category':forms.Select(choices= invoice_category_choices),
'claim_status':forms.Select(choices= claim_status_choices)
}
class ClaimStatusForm(forms.ModelForm):
class Meta:
model = ExpenseClaim
fields = [
"claim_status",
]
widgets = {
'claim_status':forms.Select(choices= claim_status_choices)
}

Answer 1

forms.py
class ClaimStatusForm(forms.ModelForm):
class Meta:
model = ExpenseClaim
fields = [
"claim_status",
]
widgets = {
'claim_status':forms.Select(choices= claim_status_choices)
}
views .py
def admin_update_view(request , reference_number):
post = get_object_or_404(ExpenseClaim , reference_number=reference_number)
form = ClaimStatusForm(instance=post)
if request.method == 'POST':
post = get_object_or_404(ExpenseClaim , reference_number=reference_number)
form = ClaimStatusForm(request.POST)
if form.is_valid():
claim_status = form.cleaned_data.get('claim_status')
post.claim_status = claim_status
post.save()
return redirect('/admin/')
context = { "form":form , "initialize_context" : initialize_context(request)}
return render(request , 'graphauth/adminupdate.html' , context)
urls.py
path('adminupdate/<int:reference_number>', views.admin_update_view , name='adminupdate'),
admin.html
update