How do I get data from mongodb, manipulate it and print it - node.js

Question

I want to connect to MongoDB and query a collection based on the filter 'category'. From the results, I want to randomly select one of entries, concatenate with another string and print to console. I am a novice at this and can't figure out how to get the results of my query and randomly select one of the entries from the query results.
//Connecting To DB
const mongoose = require('mongoose');
//const { makeCard } = require('./utils/card');
const db = mongoose.connection;
const host = process.env.host;
console.log(host)
const dbupdate = {
useNewUrlParser : true,
useUnifiedTopology : true
};
mongoose.connect(host, dbupdate);
db.on('error', (err) => console.log('Error, DB not connected'));
db.on('connected', () => console.log('connected to mongo'));
db.on('disconnected', () => console.log('Mongo is disconnected'));
db.on('open', () => console.log('Connection Made!'));
const Schema= mongoose.Schema;
const cardSchema = new Schema({
word: String,
visual : String,
category : String
});
const Card = mongoose.model('expressions', cardSchema );
--I want this function to return the results of the query, but it doesn't.
function getWords(ctgry ) {
const result = Card.find({"category" : ctgry },(error,results) => {
return results;
});
};
function getRandomInt(min, max) {
min = Math.ceil(min);
max = Math.floor(max);
return Math.floor(Math.random() * (max - min) + min);
};
function getWord( ctgry ) {
const result = getWords( ctgry );
const num = getRandomInt(0,result.length); --this doesn't work
return result[num];
};
console.log("Sample text: " + getWord());

Answer 1

What you seem to be doing here is that you're fetching all the documents from the Card model for a particular category and picking a random one from it, which I wouldn't recommend. Not sure what data you're storing here, but what if your app grows to a point where there are a million documents in your cards collection? You wouldn't fetch them all in memory and pick a random one.
A good practice while using any database is to try to only fetch as much data is required. There's no way to fetch a random document from a query in mongodb from what I know, but there's a way to do this (inspired from this answer which I recommend you read).
async function getRandomWord(ctgry) {
const count = await User.count({
"category": ctgry,
}).exec();
const random = Math.floor(Math.random() * count);
return User.findOne({
"category": ctgry,
}).skip(random).exec();
}