In Django, how do I set user field in form to the currently logged in user?

In Django, how do I set user field in form to the currently logged in user?

Django and stackoverflow noob here. I'm making an election information
app, and I want to allow the currently logged-in user to be able to
declare himself and only himself as a candidate in an election.
I'm using Django's built-in ModelForm and CreateView. My problem is that
the Run for Office form (in other words, the 'create candidate' form)
allows the user to select any user in the database to make a candidate.
I want the user field in the Run for Office to be automatically set to the
currently logged-in user, and for this value to be hidden, so the
logged-in user cannot change the value of the field to someone else.
views.py
class CandidateCreateView(CreateView):
model = Candidate
form_class = CandidateForm
template_name = 'candidate_create.html'
def form_valid(self, form):
f = form.save(commit=False)
f.save()
return super(CandidateCreateView, self).form_valid(form)
forms.py
class CandidateForm(forms.ModelForm):
class Meta:
model = Candidate
models.py
class Candidate(models.Model):
user = models.ForeignKey(UserProfile)
office = models.ForeignKey(Office)
election = models.ForeignKey(Election)
description = models.TextField()
def __unicode__(self):
return unicode(self.user)
def get_absolute_url(self):
return reverse('candidate_detail', kwargs={'pk': str(self.id)})
Thanks for reading. I've been stuck on this problem a couple days now, and
would really appreciate your help. If you need more info, please lemme
know.