def insert(self, doc, synced=False):
        doc.id = self.get_next_id()
        doc.synced = synced
        try:
            self.db.docs.insert(doc)
        except Exception as e:
            raise DatabaseException(e)
        return doc
def setSAS(self, lenp3, ap2, lenp1):
        self.lenp3 = lenp3
        self.ap2 = ap2
        self.lenp1 = lenp1
        self.lenp2 = math.sqrt((self.lenp3 * self.lenp3 + self.lenp1 * self.lenp1) - 2* self.lenp3 * self.lenp1 * math.cos(self.ap2))
        #等於 SSS(AB, BC, CA)