There has a login user problem

[zhichao Yun]

Model:
class X(models.Model):
user = models.ForeignKey(User, blank=True, null=True)
x= other()

# I want to add current user when add X

Form:
class xForm(forms.ModelForm):
class Meta:
model = X
exclude = ('marker')

View:
def add_X(request):
print request.user #user has the logined user
if request.method == 'POST':
print request.user #user is None
form = XForm(request)
if form.is_valid():
x = form.save(commit=False)
x.user = request.user
x.save()
return HttpResponseRedirect('/x/lists/')
else:
return render_to_response('x/x_form.html', {'form':xForm
()})
else:
return render_to_response('x/x_form.html', {'form':xForm()})

give me a way