mongodb，一对多，内嵌文档问题

Question

请问下，我有个用户---》多个地址
我目前把地址用内嵌文档放入用户collection，可是如果要修改地址，内嵌文档没有id怎么办？ 内嵌文档怎么实现自增id？

Answer 1

It is recommended to use uuid. To implement auto-incrementing ID, you need to manually maintain and write an auto-incrementing function in your own program. It is also more troublesome. As long as it is unique, it does not have to be auto-incrementing

Answer 2

There are two methods to implement self-increasing ID in mongodb:

1. counter collection

db.counters.insert(
   {
      _id: "userid",
      seq: 0
   }
)

function getNextSequence(name) {
   var ret = db.counters.findAndModify(
          {
            query: { _id: name },
            update: { $inc: { seq: 1 } },
            new: true
          }
   );

   return ret.seq;
}

db.users.insert(
   {
     _id: getNextSequence("userid"),
     name: "Sarah C."
   }
)

db.users.insert(
   {
     _id: getNextSequence("userid"),
     name: "Bob D."
   }
)

1. Use findAndModify()

function getNextSequence(name) {
   var ret = db.counters.findAndModify(
          {
            query: { _id: name },
            update: { $inc: { seq: 1 } },
            new: true,
            upsert: true
          }
   );

   return ret.seq;
}