multi parse

gistfile1.txt

import { NextApiRequest } from 'next';

// Inspired by https://github.com/myshenin/aws-lambda-multipart-parser

export interface FilePart {
  type: string
  filename: string
  contentType: string
  content: unknown
}

interface Part {
  [name: string]: FilePart | string
}

function getBoundary({ headers: { 'content-type': contentType } }: NextApiRequest) {
  return contentType?.toLowerCase().split('boundary=')[1].trim()
}

function itemMatch(item: string, re: RegExp) {
  const match = re.exec(item)
  if (match === null) {
    return ''
  }
  return match[1]
}

function getContent(item: string) {
  if (/filename=".+"/g.test(item)) {
    const key = itemMatch(item, /name="(.+)";/g)
    const value = {
      type: 'file',
      filename: itemMatch(item, /filename="(.+)"/g),
      contentType: itemMatch(item, /Content-Type:\s(.+)/g),
      content: item.slice(
        item.search(/Content-Type:\s.+/g) +
        itemMatch(item, /(Content-Type:\s.+)/g).length + 4,
        -4
      ),
    }
    return { [key]: value }
  } else if (/name=".+"/g.test(item)) {
    const key = itemMatch(item, /name="(.+)"/g)
    const value = item.slice(
      item.search(/name=".+"/g) + itemMatch(item, /(name=".+")/g).length + 4,
      -4
    )
    return { [key]: value }
  }
}

export function multiParse(req: NextApiRequest) {
  const boundary = getBoundary(req)
  if (!boundary) {
    return null
  }
  const fields: string[] = req.body?.split(boundary)
  if (!fields) {
    return null
  }
  return fields.reduce((result, item) => ({
    ...result,
    ...getContent(item)
  }), {} as Part)
}