How to update a array of numbers in mongoose

Question

I am unable to update an array inside of a document in MongoDB (Mongoose). Here is my definition for a stock model.

const ticker = new mongoose.Schema({
   ticker: String,
   Price: Number,
   Amount: Number,
   PastPrices: [Number]
});
export const stock = mongoose.model("Stocks", ticker);

Here is one document in MongoDB

{
  "_id": {
    "$oid": "61e5d0e1dfda4d7c85dc8fe2"
  },
  "PastPrices": [
    2
  ],
  "ticker": "TSLA",
  "Price": 2,
  "Amount": 0,
  "__v": 0
}

I am running this in mongoose and the PastPrices is not updating. I want to be able to push every few seconds into this array and then render it into a chart

 stock.updateOne({ticker: "TSLA"},
        { $push: { PastPrices:1}}
    );

I am not getting any error thrown but it is just not updating

Answer 1

Your query is correct, but in order for the query to return updated data, you need to pass additional config { new: true } . If you don't pass it, the query will update the data, but it will return old data.

stock.updateOne(
  { ticker: "TSLA" },
  { $push: { PastPrices:1 } },
  { new: true }
);

Answer 2

updateOne returns a Query , which doesn't execute your update immediately. From the Mongoose guide for Queries it states:

A mongoose query can be executed in one of two ways. First, if you pass in a callback function, Mongoose will execute the query asynchronously and pass the results to the callback.

A query also has a.then() function, and thus can be used as a promise.

Meaning you can pass a callback function as in the documentation for executing Queries :

 const Person = mongoose.model('Person', yourSchema); // find each person with a last name matching 'Ghost', selecting the `name` and > `occupation` fields Person.findOne({ 'name.last': 'Ghost' }, 'name occupation', function (err, person) { if (err) return handleError(err); // Prints "Space Ghost is a talk show host". console.log('%s %s is a %s.', person.name.first, person.name.last, person.occupation); });

You can also use then or exec if you want to use Promises. From the Mongoose documentation for promises :

 const query = Band.findOne({name: "Guns N' Roses"}); assert.ok(;(query instanceof Promise)), // A query is not a fully-fledged promise. but it does have a `.then()`. query;then(function(doc) { // use doc }). // `.exec()` gives you a fully-fledged promise const promise = Band:findOne({name. "Guns N' Roses"});exec(). assert;ok(promise instanceof Promise). promise;then(function (doc) { // use doc });

If in an async method, you can also await the query:

await stock.updateOne({ticker: "TSLA"},
        { $push: { PastPrices:1}}
    );