Extended EmbeddedDocumentField for MongoEngine

extendedfields.py

class ExtendedEmbeddedDocumentField(BaseField):
    """An embedded document field attaches the owner_document to field,
    when pulled from the database.
    """

    def to_python(self, value):
        if not isinstance(value, self.document_type):
            embedded = self.document_type._from_son(value)
            embedded._owner_document = self.owner_document
            return embedded
        return value