Mongoose：如何将之后创建的文档中的数据传递到之前创建的文档中？

Question

In my signup request, I use create two documents (in separate collections) based on two different schemas: a User model and a Client model. For context, a client will be one object referencing an array of many Users.

The User scheme includes 'clientID' field, which should hold the User's Client's ._id. Likewise, the Client's 'users' field would include an array of Users attached. The latter works OK.

On signup, I create a User, and then a Client. I am able to pass the User._id into the Client's array of users no problem. But, how do I get the Client's ._id into the User's clientID field?

The code below errors saying: Cannot access 'client' before initialization - I understand why this is happening because of the order of code.

But how do I get my code to reciprocate so that I can add the Client._id to the User's clientID field? I am sure this is a common problem, but I can't find the relevant doc on Mongoose's docs.

If anyone could help? Many thanks!

 module.exports.signup = async (req, res) => { // extract data from the req.body const { email, password, fName, lName, companyName, teams } = req.body; try { // create a new user on the User model const user = await User.create({ email: email, password: password, clientID: client._id, }); // create a new client on the Client model const client = await Client.create({ companyName: companyName, users: user._id, }); res.status(201).json(user); } catch (err) { const errors = handleErrors(err); res.status(400).json(errors); } };

Answer 1

You can instead use a specific objectId for the client when you create it and reference it later.

Just copy past the whole code:

const {ObjectID} = require('mongodb');

module.exports.signup = async (req, res) => {

  // extract data from the req.body
  const { email, password, fName, lName, companyName, teams } = req.body;

  try {

    const clientId = ObjectID();

    // create a new user on the User model
    const user = await User.create({
      email: email,
      password: password,
      clientID: clientId,
    });

    // create a new client on the Client model
    const client = await Client.create({
      companyName: companyName,
      users: user._id,
      _id: clientId
    });

    res.status(201).json(user);
  } catch (err) {
    const errors = handleErrors(err);
    res.status(400).json(errors);
  }
};

Another solution is that you can create a user without clientId and after you create client you can update the user with the created client.id :

const user = await User.create({
  email: email,
  password: password,
  // clientID: clientId,
});

// create a new client on the Client model
const client = await Client.create({
  companyName: companyName,
  users: user._id,
});

user.clientId = client._id;
await user.save();