Django: Updating models, new instance created instead of updated - django-models

Question

i am trying to make a simple profile edit form for users on a website. I've followed the standard advice for updating, in the docs it says that Django detects the instances primary key and knows to update instead of insert.
only problem is, i get an insert when i am trying to update. I pre populate a form with a model instance (the instance that im trying to edit) but when i try and save it, i get a new instance. When i add the 'force_update=True' line, i get an error message that tells me that no primary key is detected. Not sure why, because im pre populating the form with a model instance, although, obviously the pk is not a part of the form. is there something im missing?
some code:
the model:
class profile(models.Model):
user = models.ForeignKey(User)
first_name = models.CharField(max_length=20, null=True)
last_name = models.CharField(max_length=20, null=True)
DOB = models.DateField(null=True)
age = models.IntegerField(null=True)
public_email = models.EmailField(null=True)
county = models.CharField(max_length=20, null=True)
town = models.CharField(max_length=30, null=True)
the form:
class profileForm(forms.ModelForm):
class Meta:
model = profile
exclude = ['user']
the view:
#login_required()
def edit_profile(request):
if request.POST:
proform = profileForm(request.POST)
if proform.is_valid():
prof = proform.save(False)
prof.user = request.user
prof.save(force_update=True)
return HttpResponseRedirect('/accounts/view_profile/')
else:
c = {}
if profile.objects.filter(user=request.user).exists():
prof = profile.objects.get(user=request.user)
c['proform'] = profileForm(instance=prof)
else:
c['proform'] = profileForm()
return render(request, 'edit_profile.html', c)
any help greatly appreciated!

Answer 1

i got it, turns out i was trying to just calling save() on the form without specifying the particular instance that the form relates to.
code:
#login_required()
def edit_profile(request):
c = {}
if profile.objects.filter(user=request.user).exists():
profModel = profile.objects.get(user=request.user)
c['proform'] = profileForm(instance=profModel)
else:
c['proform'] = profileForm()
if request.POST:
# this line here, added 'instance=profModel' to specify
# the actual instance i want to save
proform = profileForm(request.POST, instance=profModel)
if proform.is_valid():
prof = proform.save(False)
prof.user = request.user
prof.save()
return HttpResponseRedirect('/accounts/view_profile/')
else:
return render(request, 'edit_profile.html', c)
works!