express-throwable

This package contains some lightweight middlewares for Express.js v4 which helps to use async handlers and handle errors if it was happened during request processing.

Requirements

There are no any dependencies for this package. This package compatible with Express.js v4 and required Node.js v14+. Implemented on ES7.

Do not use it with Express.js v5+.

Installation

NPM:

npm install express-throwable

PNPM:

pnpm add express-throwable

Usage

import { throwable, finalize, errorHandler } from 'express-throwable'
// omit other imports...

const app = express() // create express application
// omit app settings...

// add error handler
app.use(errorHandler((error, request, response) => { // this is optional
    // do something with error, for example add record to log
    const details = {
        error,
        url: request.originalUrl,
        params: request.params,
        query: request.query,
        headers: request.headers,
        body: request.body
    }
    logger.error('Error handled.', details)
    // by default response will get status code 500 automatically
    // but you can change this behavior
    response.status(503).end()
}))

// add another error handler
app.use(errorHandler((error, request, response) => {
    // it could be something like this:
    if (error instanceof MyCustomError) {
        // omit logic...
    }
}))

app.get('/feature/:id', throwable(async (request, response) => {
    // now your may don't care about exceptions
    response.status(200).json(await getFeature(request.params.id))
    // when exception is happened then it will be passed into error handlers
}))

// Keep in mind, each throwable handler is a final handler
// No more other middlewares can't handle request after throwable handler,
// except handler which can be passed into `finalize()`

// add last middleware to handle end of request
// it must be really last middleware, don't forget it
app.use(finalize((request, response) => {
    // do something when response is finished...
    // for example, release connections with database, etc
    // something like this:
    const { db } = request.locals
    db.release()
}))

// run server
app.listen(serverPort)

Middlewares

This package provides only three middlewares:

throwable(async (request, response) => { ... })

Use this to wrap you async handlers.

finalize(async (request, response) => { ... })

Use this for your finally code to release resources, and to execute an error handlers. It must be last middleware attached to your express application.

errorHandler(async (error, request, response) => { ... })

Use this to process an errors. Error handlers will called after callback, which you can pass into finalize().

License

MIT