Parse multipart/form-data from body as string on AWS Lambda

Question

I'm glad to see AWS now supports multipart/form-data on AWS Lambda, but now that the raw data is in my lambda function how do I process it?

I see multiparty is a good multipart library in Node for multipart processing, but its constructor expects a request, not a raw string.

The input message I am receiving on my Lambda function (after the body mapping template has been applied) is:

{ "rawBody": "--ce0741b2-93d4-4865-a7d6-20ca51fe2689\r\nContent-Disposition: form-data; name=\"Content-Type\"\r\n\r\nmultipart/mixed; boundary=\"------------020601070403020003080006\"\r\n--ce0741b2-93d4-4865-a7d6-20ca51fe2689\r\nContent-Disposition: form-data; name=\"Date\"\r\n\r\nFri, 26 Apr 2013 11:50:29 -0700\r\n--ce0741b2-93d4-4865-a7d6-20ca51fe2689\r\nContent-Disposition: form-data; name=\"From\"\r\n\r\nBob <[email protected]>\r\n--ce0741b2-93d4-4865-a7d6-20ca51fe2689\r\nContent-Disposition: form-data; name=\"In-Reply-To\"\r...  

etc and some file data.

The body mapping template I'm using is

{   "rawBody" : "$util.escapeJavaScript($input.body).replaceAll("\\'", "'")" } 

How can I parse this data to acecss the fields and files posted to my Lambda function?

Answer 1

busboy doesn't work for me in the "file" case. It didn't throw an exception so I couldn't handle exception in lambda at all.

I'm using aws-lambda-multipart-parser lib wasn't hard like so. It just parses data from event.body and returns data as Buffer or text.

Usage:

const multipart = require('aws-lambda-multipart-parser');  const result = multipart.parse(event, spotText) // spotText === true response file will be Buffer and spotText === false: String 

Response data:

{     "file": {         "type": "file",         "filename": "lorem.txt",         "contentType": "text/plain",         "content": {             "type": "Buffer",             "data": [ ... byte array ... ]         } or String     },     "field": "value" }