How to Process CSV Files in NestJS Using Multer and Papa Parse Without Storing Locally

Discover how to effectively process CSV files in NestJS with `Multer` and `Papa Parse` without local storage. Get a step-by-step guide to streamline your file handling!
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Processing CSV Files in NestJS Using Multer and Papa Parse Without Local Storage

Working with CSV files in your application can often feel daunting, especially when you want to avoid storing files locally. If you're using NestJS with Multer and Papa Parse and you're struggling with processing CSV files, you're not alone! In this guide, we will break down how to handle this situation effectively.

The Problem at Hand

In the provided scenario, there were issues when attempting to parse a CSV file within a NestJS application using the file buffer method. The main errors encountered included:

ReferenceError: FileReaderSync is not defined: This error was raised when trying to parse the buffer directly.

ERROR [ExceptionsHandler] ENAMETOOLONG: name too long, open: This arose when attempting to read the file synchronously.

These errors indicate the need for a more suitable approach to handle CSV files directly in memory.

The Solution: Convert File Buffer to a Stream

The key to solving the issue lies in streaming the file buffer before parsing. To achieve this, we need to make use of the Node.js stream module. Here's a step-by-step guide to fix the code:

Step 1: Import the Required Module

Before we proceed with the code changes, make sure to import the Readable stream from the stream module:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Update the Upload Function

Next, update your upload function to convert the file buffer into a readable stream. By transforming the buffer into a stream, we make it compatible with Papa Parse, which can then process it seamlessly.

Here’s how your updated function should look:

[[See Video to Reveal this Text or Code Snippet]]

Key Changes Explained

Using Readable.from(): This method takes the file buffer and converts it into a readable stream. This is crucial since Papa Parse requires a stream to function correctly with buffers.

Maintaining Functionality: The other parameters for parsing (header, worker, and delimiter) remain untouched, ensuring that the CSV data is handled as required.

Conclusion

By converting the file buffer to a stream, you will be able to effectively process CSV uploads in your NestJS application with Multer and Papa Parse without storing files locally. This method not only resolves the errors encountered previously but also optimizes your handling of CSV data in a user-friendly manner.

If you found this guide helpful and have further questions or need assistance, please feel free to reach out! Happy coding!