We can modify a document by directly accessing the attributes and calling save() again:

>>> user.first_name = 'Alexandros'
>>> user.save()

If we want to update one or more documents, we have to use raw() to filter out the documents that will be affected and chain update() to set the new values:

>>> User.objects.raw({'first_name': {'$exists': True}})
              .update({'$set': {'updated_at': datetime.datetime.now()}})

In the preceding example, we search for all User documents that have a first name and set a new field, updated_at, to the current timestamp. The result of the raw() method is QuerySet, a class used in PyMODM to handle queries and work with documents in bulk.