How to handle file uploads with Multer and prevent multiple file processing in Node.js?
I've encountered a strange issue with I'm sure I'm missing something obvious here, but I'm stuck on something that should probably be simple. I'm currently working on a Node.js application using Express.js and Multer for handling file uploads. I'm trying to implement a feature where users can upload a CSV file, but I'm encountering an issue where the same file is being processed multiple times if the user submits the form quickly. I need to ensure that the file is only processed once per upload session. I've set up Multer to handle the uploads, and here’s a simplified version of my code: ```javascript const express = require('express'); const multer = require('multer'); const app = express(); const upload = multer({ dest: 'uploads/' }); app.post('/upload', upload.single('file'), (req, res) => { if (req.file) { // Process the file (e.g., parse CSV) console.log(`File received: ${req.file.originalname}`); res.send('File uploaded successfully'); } else { res.status(400).send('No file uploaded'); } }); app.listen(3000, () => { console.log('Server started on port 3000'); }); ``` Currently, when I try to upload a file, if I click the upload button multiple times in quick succession, the console logs the file multiple times, indicating that the processing function is being invoked for each submission. I attempted to debounce the upload button using a simple `setTimeout` function, but it still allows the server to process the file multiple times before the debounce takes effect. Here’s the debounce code I added: ```javascript let isUploading = false; function handleUpload() { if (isUploading) return; isUploading = true; // Trigger the file upload, then reset after a delay setTimeout(() => { isUploading = false; }, 2000); } ``` This approach doesn’t seem to prevent the backend from processing the file multiple times. Is there a more effective way to ensure that each file is only processed once, regardless of how quickly the user submits the form? Should I implement some kind of session or state management for uploads? Any best practices or patterns I can apply here? Thanks in advance! For context: I'm using Javascript on Ubuntu. I'm working on a service that needs to handle this. Is there a simpler solution I'm overlooking? The project is a web app built with Javascript. Am I missing something obvious?