mongoose documentation.save() 方法不明确

Question

In the mongoose docs, it is clearly written that the.save() method is the best one to store data on mongoDB because it has validators and middlewares. This is what is written:

Note that update(), updateMany(), findOneAndUpdate(), etc. do not execute save() middleware. If you need save middleware and full validation, first query for the document and then save() it.

Therefore I wanted to use it. But I faced problems:

• Query, modify and then save the doc could make my code fail because of asynchronicity. (during the time of modify, the doc is still stored as unmodified on the DB, so if 2 modifcation happened at once, one could be erased)

• I'm using eslint and modifying the object creates a no-param-reassign error: https://eslint.org/docs/latest/rules/no-param-reassign .

async function request(userId) {
  const userToUpdate = await UserModel.findOne({ _id: userId });
  //There is time here to receive a new request that will bypass this one
  userToUpdate.value = "xxx"; 
  // The line above throws a no-param-reassign eslint error
  UserModel.save(userToUpdate);
}

Using spread operator to deconstruct doesn't work.

async function request(userId) {
  const userToUpdate = await UserModel.findOne({ _id: userId });
  //There is still time here to receive a new request that will bypass this one
  UserModel({ value: "xxx", ...userToUpdate.toObject() }).save();
}

throws =>

MongoServerError: E11000 duplicate key error collection: test.users index: _id_ dup key:

and I understand this error, it doesn't recognize the { value: "xxx", ...userToUpdate.toObject() } as the same object and think i am trying to overwrite

Anyway, I'm using updateOne for the moment, do you think you could help to make.save() work or should I stick to updateOne?

Answer 1

It's not UserModel.save(userToUpdate); it's userToUpdate.save();

Regarding the concurrent updates - mongoose uses revision control to address this issue. Try it:

const user1 = await UserModel.findOne({ _id: userId });
const user2 = await UserModel.findOne({ _id: userId }); // <-- same userId 
user1.value = "xxx"; 
await user1.save();
user2.value = "yyy"; 
await user2.save(); // <-- throws VersionControll exception

Docs: https://mongoosejs.com/docs/api/error.html#error_Error-VersionError

It's one of fundamental architectural decisions behind Mongoose. If you don't like how they handle permissions, discrimination, or population it would be advisable to do not use the ODM - you will end up fighting it instead of using it. It was not designed one-size-fits-all, but rather focused to simplify specific usecases.