JavaScript Mongoose DB script hangs on drop() operation

Desired behavior: drop the collection if it exists, otherwise proceed with script.

One of my scripts never gets past the drop() operation.

The connection string is correct, and the connection is active, because other scripts are able to make DB insertions without any issue. Furthermore, console.log(connection.readyState); gives a state of 1, right before the operation that hangs.

I have alternately tried drop.database() as well as drop().

const axios = require("axios");
const XLSX = require("xlsx");
const fs = require("fs");
const path = require("path");
const mongoose = require("mongoose");
const connection = require("../../../config/connection");
const MdProdCat = require("../../../models/MdProdCat");
(async () => {
try {
// Download the .xlsx file
console.log("=== Commencing MD Product Category import...");
console.log("Downloading .xlsx file...");
const response = await axios.get(
"https://assets.mydeal.com.au/content/marketplace/MyDeal_Product_Category_List.xlsx",
{ responseType: "arraybuffer" }
);
console.log("Saving .xlsx file...");
// Save the file to the project directory
console.log("Saving .xlsx file...");
const xlsxFilePath = path.join(
__dirname,
"MyDeal_Product_Category_List.xlsx"
);
fs.writeFileSync(xlsxFilePath, Buffer.from(response.data));
console.log("Saved .xlsx file");
// Convert the .xlsx file to .csv format
console.log("Converting .xlsx to .csv...");
const workbook = XLSX.read(response.data, { type: "buffer" });
const sheetNameList = workbook.SheetNames;
const csvData = XLSX.utils.sheet_to_csv(workbook.Sheets[sheetNameList[0]]);
console.log("Converted .xlsx to .csv");
// Convert the CSV data to an array of JSON objects
console.log("Converting .csv to JSON...");
const rows = csvData.split("\n").slice(1); // skip the header row
const json = rows
.filter((line) => line.trim()) // skip empty rows
.map((line) => {
const [CategoryID, Breadcrumbs] = line.split(",");
return { _id: parseInt(CategoryID), Breadcrumbs };
});
console.log("Converted .csv to JSON");
// Check the connection to the database
console.log("Connection state: ", connection.readyState);
// Wait for the connection to be established
connection.once('connected', async () => {
// // Drop the database in case it already exists
// console.log("Dropping the database if it already exists");
// await connection.db.dropDatabase();
// Drop the collection in case it already exists
try {
// Drop the collection
console.log("Dropping collection if it already exists");
await connection.dropCollection('mdprodcats');
console.log("Collection dropped successfully");
} catch (error) {
if (error.message === 'ns not found') {
// Ignore the error if the collection does not exist
console.log('Collection does not exist. Continuing...');
} else {
// Throw any other errors
throw error;
}
}
// Insert the JSON data into the MongoDB collection
console.log("Inserting data...");
await MdProdCat.insertMany(json);
console.log("Data inserted successfully");
// Close the connection
console.log("Closing connection...");
await connection.close();
console.log("Connection closed");
console.log("=== Import completed successfully");
process.exit();
});
} catch (error) {
console.error("An error occurred:", error);
process.exit(1);
}
})();

Terminal output:

MongoDB connection state: 2
=== Commencing MD Product Category import...
Downloading .xlsx file...
Saving .xlsx file...
Saving .xlsx file...
Saved .xlsx file
Converting .xlsx to .csv...
Converted .xlsx to .csv
Converting .csv to JSON...
Converted .csv to JSON
Connection state:  1

After which the script hangs indefinitely.

Tried: removing the drop() operation reveals the problem to be of a broader nature as the subsequent await MdProdCat.insertMany(json); does not work either.

Removing this wrapper worked:

connection.once('connected', async () => {
})

I still cannot understand why it worked, but it seems to have worked. Feel free to drop a comment below if you can explain why.