How can I retrieve a list of field for all objects in Django?

I want to retrieve a list of all of the values for one field from a query in django. For example, I have a query of users, but rather than a queryset (or list) of user objects, I want a list just the usernames (strings). In a sense this is asking to restrict only to one column of data.

Have you tried

list(User.objects.all().values_list('username', flat=True)) 

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. Additionally, casting it to a list makes the returned value a list instead of a queryset

To get the list of usernames:

>>> User.objects.all().values('username')
>>> [{'username': u'u1'}, {'username': u'u2'}]

>>> User.objects.all().values_list('username')
>>> [(u'u1',), (u'u2',)]

If you want just strings, a list comprehension can do the trick:

>>> usr_names = User.objects.all().values('username')
>>> [u['username'] for u in usr_names]
>>> [u'u1', u'u2']

Using values_list:

>>> usr_names = User.objects.all().values_list('username')
>>> [u[0] for u in usr_names]
>>> [u'u1', u'u2']

As you wrote:

"but rather than a queryset (or list) of user objects"

Soulution above still queryset

usr_names = User.objects.all().values_list('username')

This solution:

usr_names = [str(elem) for elem in list(User.objects.all().values_list('username'))]

It will return a list of strings

The simplest way you can get the list of objects of an attribute is to first get a query-set of that attribute alone using values_list then converting the django query-set to a python set using set() and finally to a list using list().

In your scenario:

user_names = list(set(User.objects.all().values_list('username', flat=True)))