MongoEngine/mongoengine — pull request #494 by cdesaintleger (2013-10-16 14:44:36+00:00)
Title: Give the choice to create a copy or dbref from a document in a dynamic Field

# Use a copy if value is a document
myField = DynamicField(use_dbref=False)

# Use a DBRef if value is a Document
myField = DynamicField()
#or
myField = DynamicField(use_dbref=True)