网上资料不好搜，记下来：两个变量：id bson.ObjectIdstr string
bson.ObjectId—>string
id.Hex()
string—>bson.ObjectId
bson.ObjectIdHex(str)
golang:bson.ObjectId与string转化
原文：https://www.cnblogs.com/dfsxh/p/10206601.html
