class Post(EmbeddedDocument):
    uid = StringField(required=True)
text = StringField(required=True)


class Feed(Document):
    label = StringField(required=True)
feed_url = StringField(required=True)
posts = ListField(EmbeddedDocumentField(Post))
Feed.drop_collection()
Feed(label='label', feed_url='www.feed.com').save()
Updating a list of embedded documents in mongoengine