title: get_or_create() question
body: <p>From the official documentation I can't understand what is default parameter.</p>
  
  <pre><code>obj, created = Person.objects.get_or_create(first_name='John', last_name='Lennon',
                    defaults={'birthday': date(1940, 10, 9)}
  </code></pre>
  
  <p>Does it mean that it will look for fields which match both <code>John</code> and <code>Lennon</code> parameter and birthday will just insert? Can I use something else instead of defaults?</p>
  
  <p>And what method should I use to clean all fields in table (models)?</p>
  
  <p>It give me FileField error can not resolve keyword default in field</p>
  
  <p>So I need look for fiels, if i found it - update datas. If i didn't find it I have to crate new field... But, as I understud, It won't update me default fields when finde present fields. </p>