title: django model validation not working
body: <p>I have the following model:</p>
  
  <pre><code>class CardInfo(models.Model):
      custid = models.CharField(max_length=30, db_index=True, primary_key = True)
      first_name = models.CharField(max_length=100)
      last_name = models.CharField(max_length=100)
      street = models.CharField(max_length=100)
      building = models.CharField(max_length=100)
      city = models.CharField(max_length=100)
      state = models.CharField(max_length=100)
      zipcode = models.CharField(max_length=100)
      payment_method = models.CharField(max_length=100, null=True, blank=True)
      amount = models.CharField(default = '0',max_length=10, null=True, blank=True)
      valid_to_month = models.CharField(max_length=100, null=True, blank=True)
      valid_to_year = models.CharField(max_length=100, null=True, blank=True)
  def __unicode__(self):
      return "Cust ID %s" %(self.custid)
  </code></pre>
  
  <p>In the shell, when i give full_clean i get validation error but on save it s getting saved rather than throwing error. why is this so? i am using django1.3 and python 2.6:</p>
  
  <pre><code>c=CardInfo(custid="Asasasas")
  c.full_clean()
  Traceback (most recent call last):
  File "&lt;console&gt;", line 1, in &lt;module&gt;
  File "/usr/local/python2.6/lib/python2.6/site-packages/django/db/models/base.py", line 828, in full_clean
  raise ValidationError(errors)
  ValidationError: {'building': [u'This field cannot be blank.'], 'city': [u'This field cannot be blank.'], 'first_name': [u'This field cannot be blank.'], 'last_name': [u'This field cannot be blank.'], 'zipcode': [u'This field cannot be blank.'], 'state': [u'This field cannot be blank.'], 'street': [u'This field cannot be blank.']}
  c.save()
  </code></pre>