解决方法
你有没有尝试过
User.objects.all().values_list('username',flat=True)
如这里所述
https://docs.djangoproject.com/en/1.4/ref/models/querysets/#values-list
If you only pass in a single field,you can also pass in the flat parameter. If True,this will mean the returned results are single values,rather than one-tuples.