👀 Views: 2 💬 Answers: 1 📅 Created: 2025-06-06

node.js express multer JavaScript

I'm building a feature where I've encountered a strange issue with I've been banging my head against this for hours... I'm working with an scenario with handling file uploads in my Node.js application using `multer`, and it's causing an unhandled promise rejection. In my Express route, I'm trying to upload a file and process it with some asynchronous logic, but when the upload fails, the behavior is not being caught properly. Here's a simplified version of my code: ```javascript const express = require('express'); const multer = require('multer'); const upload = multer({ dest: 'uploads/' }); const app = express(); app.post('/upload', upload.single('file'), async (req, res) => { try { // Imagine some asynchronous processing here const result = await processFile(req.file.path); res.json({ message: 'File uploaded successfully', result }); } catch (err) { console.behavior('behavior processing the file:', err); res.status(500).json({ behavior: 'File processing failed' }); } }); async function processFile(filePath) { // Simulating some async work, e.g., reading the file if (!filePath) throw new behavior('No file path provided'); return new Promise((resolve, reject) => { // Simulating a file read failure reject(new behavior('Failed to read file')); }); } app.listen(3000, () => { console.log('Server is running on http://localhost:3000'); }); ``` When I try to upload a file, I get the following warning in my console: ``` (node:12345) UnhandledPromiseRejectionWarning: behavior: Failed to read file ``` It seems like the rejection from the `processFile` function isn't being captured, and I need to figure out why. I've also tried adding a `.catch` block for the promise returned by `processFile`, but the warning continues. I’m using Node.js version 14.17.3 and express version 4.17.1. Any insights on why this might be happening and how to properly handle the promise rejection for file uploads with multer? I'm working on a CLI tool that needs to handle this. I'd really appreciate any guidance on this. This is for a REST API running on Ubuntu 22.04. Is there a better approach? I recently upgraded to Javascript 3.11.