HTTP Problem Details for express

Based on http-problem-details (repository | npm) and http-problem-details-mapper (repository | npm), this library allows you to map your Node.js errors to HTTP Problem details according to RFC7807 by convention.

Installation

``
npm install express express-http-problem-details
`

or

`
yarn add express express-http-problem-details
`

Usage

express-http-problem-details provides a middleware which allows you to map custom Error instances to HTTP Problem Details documents according to RFC7807.

The details of the mapping itself are described in http-problem-details-mapper (repository | npm)

$3

The typical workflow in JavaScript/ES2015 with http-problem-details-mapper is this:

First, you implement an Error

`js
class NotFoundError extends Error {
constructor (options) {
const { type, id } = options
super()
Error.captureStackTrace(this, this.constructor)

this.message = ${type} with id ${id} could not be found.
}
}
`

Next, you extend the ErrorMapper class:

`js
import { ProblemDocument } from 'http-problem-details'
import { ErrorMapper } from 'http-problem-details-mapper'

class NotFoundErrorMapper extends ErrorMapper {
constructor() {
super(NotFoundError)
}

mapError (error) {
return new ProblemDocument({
status: 404,
title: error.message,
type: 'http://tempuri.org/NotFoundError'
})
}
}
`

Finally, create an instance of ExpressMappingStrategy to hold the mappers and register everything in your app.
Notice that the HttpProblemResponse must come last. A global error logger would
precede it and forward the error to the next function.

`js
import { HttpProblemResponse } from 'express-http-problem-details'
import { DefaultMappingStrategy, MapperRegistry } from 'http-problem-details-mapper'

const strategy = new DefaultMappingStrategy(
new MapperRegistry()
.registerMapper(new NotFoundErrorMapper()))


const server = express()

server.get('/', async (req, res) => {
return res.send(new NotFoundError({type: 'customer', id: '123' }))
})
server.use(function logErrors (err, req, res, next) {
console.error(err.stack)
next(err)
})
server.use(HttpProblemResponse({strategy}))

server.listen(3000)
`

When GETting localhost:3000, the result will be like this:

`bash
HTTP/1.1 404 Not Found
Connection: keep-alive
Content-Length: 107
Content-Type: application/problem+json; charset=utf-8
Date: Wed, 24 Apr 2019 23:48:27 GMT
ETag: W/"6b-dSoRnzOA0Ls+QaHyomC8H+uv7GQ"
X-Powered-By: Express

{
"status": 404,
"title": "customer with id 123 could not be found.",
"type": "http://tempuri.org/NotFoundError"
}

`

When just returning a return res.status(500).send();, you'll get a response like this:

`bash
HTTP/1.1 500 Internal Server Error
Connection: keep-alive
Content-Length: 67
Content-Type: application/problem+json; charset=utf-8
Date: Thu, 25 Apr 2019 00:01:48 GMT
ETag: W/"43-U3E8vFCP1+XTg1JqRHkrjQWiN60"
X-Powered-By: Express

{
"status": 500,
"title": "Internal Server Error",
"type": "about:blank"
}

`

Running the tests

`
npm test
`

or

`
yarn test
`

Want to help?

This project is just getting off the ground and could use some help with cleaning things up and refactoring.

If you want to contribute - we'd love it! Just open an issue to work against so you get full credit for your fork. You can open the issue first so we can discuss and you can work your fork as we go along.

If you see a bug, please be so kind as to show how it's failing, and we'll do our best to get it fixed quickly.

Before sending a PR, please create an issue to introduce your idea and have a reference for your PR.

We're using conventional commits, so please use it for your commits as well.

Also please add tests and make sure to run npm run lint-ts or yarn lint-ts`.

License

MIT License

Copyright (c) 2019 PDMLab

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.