Parsing 'multipart/form-data' Excel (.xlsx) with Busboy on AWS Lambda (Node.js)

upload.js

'use strict'

const Busboy = require('busboy')
const XLSX = require('xlsx')

function parseMultipartFormData(input, contentType) {
  return new Promise((resolve, reject) => {
    const buffers = []
    const busboy = new Busboy({
      headers: { 'content-type': contentType },
    })
    busboy.on('file', (fieldname, file, filename, encoding, mimetype) => {
      file.on('data', data => {
        buffers.push(data);
      })
      file.on('end', () => {
        resolve(Buffer.concat(buffers));
      })
    })
    busboy.on('error', error => reject(error))
    busboy.end(input)
  })
}

module.exports.upload = async (event, context) => {
  try {
    const contentType = event.headers['content-type'] || event.headers['Content-Type']
    const data = await parseMultipartFormData(event.body, contentType)
    const workbook = XLSX.read(data, { type: 'buffer' })
    const jsonRows = XLSX.utils.sheet_to_json(workbook.Sheets[workbook.SheetNames[0]])
    console.log(jsonRows)
  } catch (error) {
    console.log(error)
  }
}