Chaining promise to update a reference document in Mongoose - node.js

Question

Given the following schema:
user
{ uid:12345, name:myname, account=null }
account
{ _id:6789, name:"myaccount", _owner:12345 }
How can I update the user.account to have the value of its referenced field account._owner. When the account document is created I want to find and replace the user.account value. The route I have looks like this:
app.post('/accounts', authenticate, (req, res) => {
var account = new Account({
name: req.body.name,
_owner: req.body._owner,
});
account.save().then((doc) => {
//here i wasnt to update a refernce to a
// an account field in a User document and set
//it to the account.owner created above.
res.send(doc);
}, (e) => {
res.status(400).send(e);
});
});
In my example when the account is created
I want to update user.account to 6789 (the value of the created account id)

Answer 1

Mongoose handles promises : http://mongoosejs.com/docs/promises.html
So you can simply :
app.post('/accounts', authenticate, (req, res) => {
var account = new Account({
name: req.body.name,
_owner: req.body._owner,
});
account.save()
.then((doc) => User.findOneAndUpdate(
{ uid: req.body._owner },
{ $set: { account: doc._id } },
{ new: true }
)
.then(() => doc);
}).then((account) => {
res.send(account);
}, (e) => {
res.status(400).send(e);
});
});

Answer 2

Another solution would be to attach a hook to the save action of account model
var Owner = require('path/to/owner/model');
var schema = new Schema({name:String,_owner:{type: Schema.Types.ObjectId,ref: 'owner'}}); // ref will be useful if you want to use populate later
schema.post('save', function(account) {
return Owner.findOne({uid:account._owner})
.then(owner => {
owner.account = account._id; // assign account id to user
return owner.save();
})
});
Then you just have to create a new account object and the hook will do it in the background.
app.post('/accounts', authenticate, (req, res) => {
var account = new Account({
name: req.body.name,
_owner: req.body._owner,
});
account.save().then((doc) => {
res.send(doc);
}, (e) => {
res.status(400).send(e);
});
});
IMO, the routes look cleaner this way, you could try it out.