title: Populating existing fields in Django model
body: <p>I have a model and one of it's fields is defined as <code>blank=True, null=True</code>. I changed both to <code>False</code> and wrote a callable function that returns random strings. I set that function as the <code>default=</code> of that field, and then I ran <code>makemigrations</code> and <code>migrate</code>, but I keep seeing blank fields in my table.</p>
  
  <p>Is that expected behaviour? And if so, how can I populate all existing fields?</p>
  
  <p>I'm using Django 1.10</p>