@molecule/api-middleware-body-parser-express

Express body parser provider for molecule.dev.

Auto-generated, AI-first package reference for the molecule.dev ecosystem. It is written to be read by coding agents as much as by people, and is generated from this package's source — edit src/index.ts JSDoc, not this file.

Quick Start

import { setBodyParser, setJsonParserFactory } from '@molecule/api-middleware-body-parser'
import { provider, jsonParserFactory } from '@molecule/api-middleware-body-parser-express'

setBodyParser(provider)
setJsonParserFactory(jsonParserFactory)

Type

provider

Installation

npm install @molecule/api-middleware-body-parser-express @molecule/api-bond @molecule/api-i18n @molecule/api-middleware-body-parser connect-busboy express
npm install -D @types/connect-busboy @types/express

API

Functions

`provider(req, res, next)`

Express body parser middleware provider.

Routes requests to the appropriate parser: busboy for multipart/form-data and URL-encoded bodies, or Express's built-in JSON parser for everything else. Sets req.rawBody for Stripe and similar libraries that need the unparsed body.

For file uploads, use @molecule/utilities-files.

function provider(req: unknown, res: unknown, next: (err?: unknown) => void): void

req — The incoming request object.
res — The response object.
next — The next middleware function.

`jsonParserFactory(options)`

Creates a JSON body parser middleware with custom options (e.g. custom limit, type, or verify).

function jsonParserFactory(options?: JsonParserOptions): Middleware

options — Express JSON parser options passed directly to express.json().

Returns: A Middleware that parses JSON request bodies with the specified options.

Core Interface

Implements @molecule/api-middleware-body-parser interface.

Bond Wiring

Setup function to register this provider with the core interface:

import { setJsonParserFactory } from '@molecule/api-middleware-body-parser'
import { jsonParserFactory } from '@molecule/api-middleware-body-parser-express'

export function setupMiddlewareBodyParserExpress(): void {
  setJsonParserFactory(jsonParserFactory)
}

Injection Notes

Requirements

Peer dependencies:

@molecule/api-bond ^1.0.1
@molecule/api-i18n ^1.0.1
@molecule/api-middleware-body-parser ^1.0.1
express ^5.0.0

Runtime Dependencies

@molecule/api-bond
@molecule/api-i18n
@molecule/api-middleware-body-parser
connect-busboy
express
Wire BOTH setters (as in the example): setBodyParser(provider) registers the parser the core bodyParser middleware delegates to — wiring only the factory leaves getBodyParser() throwing on the first request.
JSON bodies are capped at 2 MB (413 beyond it). For larger payloads create a custom parser via setJsonParserFactory(jsonParserFactory) + createJsonParser({ limit: '10mb' }) from the core.
multipart/form-data and application/x-www-form-urlencoded are parsed by busboy: file parts are skipped (streams drained — use @molecule/utilities-files for uploads), and each field value is JSON-parsed when possible ("123" → number 123, "true" → true; invalid JSON stays a string). Cumulative field bytes are capped at 2 MB (413).
req.rawBody (a STRING copy of the unparsed body, for Stripe-style webhook signature verification) is set only on the JSON path — multipart requests never get it.

`@molecule/api-middleware-body-parser-express`

How it works

Reference