Properly retrieve and display data from Mongoose / MongoDB .find method - node.js

Question

I am working on a command line app in Node.js that involves retrieving results from a database (DB) using Mongoose. One important function I created just is not working no matter how hard I try and how many tutorials I go through.
The main purpose of the function is to look and see if the database (a simple word bank) has an entry containing given phrase / word.
Here is the full code setup for the particular function:
const mongoose = require('mongoose'),
mongoSettings = {
useNewUrlParser: true,
useUnifiedTopology: true
},
wordSchema = new mongoose.Schema(
{ item: String }
);
/**
* Looks for a given word or phrase in database.
* Will eventually return a boolean.
*
* #param {string} word2LookUp Word or phrase to search for
* #param {string} lang Which language list to search in [english (default), spanish, or french]
*/
const inWordBank = (word2LookUp,lang="english") => {
mongoose.connect('mongodb://localhost:27017/word-bank', mongoSettings);
mongoose.connection
.once("open",()=>{
console.log(`// ----- Searching for: "${word2LookUp}"...`);
const Word = mongoose.model('Word', wordSchema,lang);
Word.find({item: word2LookUp}, function (err, words) {
console.log(words); // <---------[ WHERE I'M HAVING TROUBLE ]
});
mongoose.connection.close();
})
.on("error", error => {
console.log(">>> Error: ",error)
mongoose.connection.close();
});
}
module.exports = {
inWordBank: inWordBank
}
This is how I am trying to execute the function on my app.js file:
const wordBank = require("./wordBank");
wordBank.alreadyRegistered("fem");
All I get in the console is:
// ----- Searching for: "fem"...
undefined
undefined
undefined
Some additional tidbits:
There's 3 documents in the particular DB in question that contain "fem" in their "item" section. That's probably why there is undefined 3 times for some odd reason.
The DB works fine when I write to it so I know it's not a connection issue
There are no other errors generated.
In my package.json file, my dependencies look like this:
"devDependencies": {
"chai": "^4.2.0",
"mocha": "^6.2.2"
},
"dependencies": {
"mongoose": "^5.7.10"
}
Is there an important piece of the puzzle I'm simply missing? Or do I have to rewrite this from square 1?

Answer 1

Right now you are searching for the exact value of word2Lookup. To search for documents who's item contains a string, you have to use regex.
So for wordBank.alreadyRegistered("fem"); try using wordBank.alreadyRegistered(/fem/g);.
Or, at the top of inWordBank() you can take the passed string and make a regex out of it like so: word2Lookup = new RegExp(word2Lookup, 'g');. Just put that at the top of your inWordBank() function.
Edit: There is another issue. Since the value is returning undefined, there is actually an error being thrown by MongoDB. Do console.log(err); inside the find callback and that will tell you the error.

Answer 2

As #chirspytoes says it is important to verify if there is no error, you can do it as follows:
Word.find({item: word2LookUp}, function (err, words) {
if(err) {
console.error(err);
return;
}
console.log(words);
});
The second thing to consider is that the results obtained with the find() method come as an array.
Example:
[
{
"item": "fem..."
},
{
"item": "...fem"
},
{
"item": "fem"
},
]