Express Msgpack


[Express] and [MessagePack], together at last. Uses [@msgpack/msgpack][1] by default.

Functionality

Provides transparent middleware that can be used to support clients requesting
Accept: application/msgpack from endpoints using res.json or sending
Content-Type: application/msgpack to any endpoint. You can continue to use
req.body and res.json and expressMsgpack will handle the conversion in
the background using @msgpack/msgpack (or any compatible library of your
choice).

Installation

``bash
$ npm install --save express-msgpack
// or
$ yarn add express-msgpack
`

If you intend to use an alternative to @msgpack/msgpack (see Configuration)
you can add the --no-optional flag; it's an optional dependency.

Usage

`javascript
import msgpack from "express-msgpack";

// ...
app.use(msgpack());
`

$3

`javascript
const msgpack = require("express-msgpack").default;

// ...
app.use(msgpack());
`

Configuration

To configure, pass options when you configure the middleware. Currently supported options are:

| Parameter | Description | Default |
|---|---|---|
| allowUnacceptableResponse | a boolean indicating whether the response should still be sent if the client doesn't set a compatible Accept type (rather than a 406 Not Acceptable response) | false |
| decoder | a function converting from MessagePack to JavaScript | @msgpack/msgpack#decode |
| encoder | a function converting from JavaScript to MessagePack | @msgpack/msgpack#encode (with a wrapper to convert the result to a Buffer) |
| mimeType | the MIME type to detect and set for MessagePack payloads | "application/msgpack" |
| limit | The byte limit of the body. This is the number of bytes or any string format supported by bytes | "100kb" |

For example, to switch to the node-gyp C++ based [msgpack] library:

`javascript
import msgpack from "express-msgpack";
import { pack, unpack } from "msgpack";

// ...
app.use(msgpack({ decoder: unpack, encoder: pack }));
`

Development

The project has code linting and testing, using the following commands:

- npm run e2e: run the smoke/E2E tests
- npm run lint: run the ESLint checks
- npm run ship: lint and run unit, integration and E2E tests
- npm test: run the Jest unit and integration tests
- npm test:watch: run the tests in watch mode

The tests are in the __tests__/ directory and are run using [Jest]. They're
split into two files:

- unit.test.ts - mockist unit tests, to check specific internal details
- integration.test.ts - integration tests using [SuperTest] with a simple
Express app using the middleware

There is also a smoke.test.js file containing E2E/smoke tests for a deployed
version of the package, used by bin/smoke.js. If the --local argument is
supplied to the script the local version is packaged and tested , otherwise
the specified -tag` version is installed from the registry and tested.

[Express]: https://expressjs.com/
[Jest]: https://jestjs.io/
[MessagePack]: https://msgpack.org/
[msgpack]: https://www.npmjs.com/package/msgpack
[SuperTest]: https://github.com/visionmedia/supertest
[1]: https://www.npmjs.com/package/@msgpack/msgpack