aws-multipart-parser

0.2.1 verified Sat Apr 25 auth: no javascript

A lightweight parser for multipart/form-data requests in AWS Lambda environments. Version 0.2.1 provides typed output and supports binary file data, addressing limitations of the parent library myshenin/aws-lambda-multipart-parser. Released as needed, it is a dependency-free utility requiring API Gateway binary support configuration. Differentiates with TypeScript types and explicit handling of binary fields, unlike alternatives that may lack type safety or ignore binary content.

Common errors

error TypeError: Cannot read properties of undefined (reading 'split') ↓

cause Event object missing 'headers' property or 'Content-Type' header without boundary.

fix

Ensure API Gateway is configured to pass headers, or invoke lambda with proper multipart request.

error Parsed form data is empty but request contains form fields ↓

cause API Gateway binary support not enabled for multipart/form-data.

fix

Enable binary media types on API Gateway, specifically 'multipart/form-data'.

error Property 'type' does not exist on type 'ParsedFormData' ↓

cause TypeScript type mismatch; older versions may not include type exports.

fix

Update to aws-multipart-parser@0.2.1 and import type { ParsedFormData }.

Warnings

gotcha API Gateway binary support must be enabled (multipart/form-data) or parsing will fail silently or return empty results. ↓

fix Add 'multipart/form-data' to API Gateway binary media types, or use serverless-apigw-binary plugin.

gotcha The second parameter 'force' defaults to false; if false, the parser only works when Content-Type includes boundary. Missing boundary causes parse failure. ↓

fix Always pass true as second argument to force parsing, or ensure proper boundary in headers.

deprecated The parent library (myshenin/aws-lambda-multipart-parser) is no longer maintained; this fork is the recommended replacement. ↓

fix Migrate to aws-multipart-parser for TypeScript support and bug fixes.

gotcha File fields are returned as strings (base64) rather than Buffer; binary data processing requires decoding. ↓

fix Use Buffer.from(fileValue, 'base64') to get binary data for further processing.

Install

npm install aws-multipart-parser

yarn add aws-multipart-parser

pnpm add aws-multipart-parser

Imports

parse

wrong

const parse = require('aws-multipart-parser').parse

correct

import { parse } from 'aws-multipart-parser'

Library is ESM-first; CommonJS require still works but tree-shaking may be affected.

default

wrong

const awsMultipartParser = require('aws-multipart-parser')

correct

import awsMultipartParser from 'aws-multipart-parser'

Default export is the parse function itself; named import is preferred for clarity.

ParsedFormData
```
import type { ParsedFormData } from 'aws-multipart-parser'
```
Type import for TypeScript users; not available as a runtime export.

parse

wrong

const parse = require('aws-multipart-parser');

correct

const { parse } = require('aws-multipart-parser')

CommonJS pattern works but some bundlers may optimize poorly.

Quickstart

Shows how to import and use the parse function in an AWS Lambda handler, including error handling and TypeScript integration.

import { parse } from 'aws-multipart-parser';

export const handler = async (event) => {
  try {
    const formData = parse(event, true);
    console.log('Parsed fields:', formData.fields);
    console.log('Parsed files:', formData.files);
    return {
      statusCode: 200,
      body: JSON.stringify({ message: 'Success', data: formData }),
    };
  } catch (error) {
    return {
      statusCode: 400,
      body: JSON.stringify({ error: 'Failed to parse request', details: error.message }),
    };
  }
};