DoesNotExist exception when using custom clean method

In my application I have an extended User model called UserProfile. This user can add up to 4 Friend models. Each added Friend is related 1 to 1 with UserProfile. In my AddFriend form I have a custom cleaning method, for pid field (personal id). This clean_pid should check if the user with given pid is already registered/added as friend and return proper ValidationError. After submitting the form (with no instances in Friend table) I'm getting :

DoesNotExist at /user/add_friend/
UserProfile matching query does not exist.

If there are no users matching sent 'pid', it's value should be returned. Why it's not working ?

Traceback :

File "/home/rails/fandrive/site-packages/django/core/handlers/base.py" in get_response
  92.                 response = callback(request, *callback_args, **callback_kwargs)
File "/home/rails/fandrive/site-packages/django/contrib/auth/decorators.py" in __call__
  78.             return self.view_func(request, *args, **kwargs)
File "/home/rails/fandrive/accounts/views.py" in add_friend
  22.         if form.is_valid():
File "/home/rails/fandrive/site-packages/django/forms/forms.py" in is_valid
  120.         return self.is_bound and not bool(self.errors)
File "/home/rails/fandrive/site-packages/django/forms/forms.py" in _get_errors
  111.             self.full_clean()
File "/home/rails/fandrive/site-packages/django/forms/forms.py" in full_clean
  243.                     value = getattr(self, 'clean_%s' % name)()
File "/home/rails/fandrive/accounts/forms.py" in clean_pid
  48.             user = UserProfile.objects.get(pid=self.cleaned_data['pid'])
File "/home/rails/fandrive/site-packages/django/db/models/manager.py" in get
  120.         return self.get_query_set().get(*args, **kwargs)
File "/home/rails/fandrive/site-packages/django/db/models/query.py" in get
  305.                     % self.model._meta.object_name)

Models :

class InheritedProfile(models.Model):
    pid = models.CharField("PID", max_length=11, blank=True, null=True)
(...)
    class Meta:
        abstract=True

class UserProfile(InheritedProfile):
(...)
    user = models.ForeignKey(User, unique=True, related_name='profile')

class Friend(InheritedProfile):
(...)
    friend_of = models.ForeignKey(UserProfile, related_name='friend_of')

Forms :

class FriendForm(forms.ModelForm):
    pid = forms.RegexField(regex=r'^\d{11}', max_length=11 ,widget=forms.TextInput(attrs=dict(attrs_dict, maxlength=50)))
(...)    
    class Meta:
        model = Friend
        exclude = ( 'friend_of', )

    def clean_pid(self):
        try:
            user = UserProfile.objects.get(pid=self.cleaned_data['pid'])
        except User.DoesNotExist:
            try:
                user = Friends.objects.get(pid=self.cleaned_data['pid'])
            except Friend.DoesNotExist:
  开发者_C百科              return self.cleaned_data['pid']
            raise forms.ValidationError(_(u'User is somebody's friend.'))
        raise forms.ValidationError(_(u'User with given PID already registered.'))

    def save(self, user, *args, **kwargs):
        self.instance.friend_of = user                           
        post = super(FriendForm, self).save(*args, **kwargs)
        post.save()
        return post

Views (not sure if they're needed):

def add_friend(request):
    userprofile = UserProfile.objects.get(user=request.user)
    count = 0

    if request.method == 'POST':
        form = FriendForm(request.POST, request.FILES,)
        if form.is_valid():
            count = Friend.objects.filter(friend_of=userprofile).count() 
            if not count > 5:
                form.save(user=request.user)            
                next = reverse('user_profile',)
            else:
                msg = "You already have 4 friends"
                render_to_response('user/data_operations/error.html', {'msg': msg}, context_instance=RequestContext(request))
            return HttpResponseRedirect(next)
    else:
        form = FriendForm()
    return render_to_response('user/data_operations/add_friend.html', {
            'form':form, 'user':request.user,
            }, context_instance=RequestContext(request))

try:
    user = UserProfile.objects.get(pid=self.cleaned_data['pid'])
except user.DoesNotExist:
    ...

It's because you try to get UserProfile object but check for user object DoesNotExists, not UserProfile.

Change this: except User.DoesNotExist: to this: except UserProfile.DoesNotExist: