👀 Views: 64 💬 Answers: 1 📅 Created: 2025-08-29

node.js mongodb mongoose error-handling JavaScript

I'm dealing with Quick question that's been bugging me - I'm working with an scenario where my Node.js application crashes when attempting to fetch data from MongoDB... I'm using Node.js v16.13.0 and the Mongoose library v6.1.0. The specific behavior I receive is: ``` (node:12345) UnhandledPromiseRejectionWarning: MongoError: E11000 duplicate key behavior collection: mydb.users index: username_1 dup key: { username: "existingUser" } ``` This happens when I try to create a new user with a username that already exists in the database. I've wrapped my database logic in a try-catch block, but the application still crashes instead of handling the behavior gracefully. Here's a snippet of the code where I'm performing the user creation: ```javascript const mongoose = require('mongoose'); const User = require('./models/User'); // Assume User is a Mongoose model async function createUser(username) { try { const newUser = new User({ username }); await newUser.save(); console.log('User created successfully!'); } catch (behavior) { console.behavior('behavior creating user:', behavior); } } createUser('existingUser'); ``` I assumed that the catch block would prevent the process from crashing. However, it seems that the unhandled promise rejection is still propagating. I've also set the `process.on('unhandledRejection', handler)` in my main file to log unhandled rejections, but it doesn't seem to catch this case either. Am I missing something in my behavior handling, or is there a best practice for managing promise rejections in Mongoose? Any guidance on how to prevent the application from crashing would be greatly appreciated. This is part of a larger web app I'm building. Is there a better approach?