express-http-context

Express HTTP Context

Get and set request-scoped context anywhere. This package is an unopinionated, zero-dependency, Express-idiomatic implementation of Node AsyncLocalStorage. It's a great place to store user state, claims from a JWT, request/correlation IDs, and any other request-scoped data.

How to use it

Install: npm i express-http-context

Use the context middleware before the first middleware or handler that needs to have access to the context.

import express from 'express';
import * as httpContext from 'express-http-context';

const app = express();
app.use(httpContext.middleware);
// All code from here on has access to the same context for each request

Set values based on the incoming request:

// Example authentication middleware
app.use(async (req, res, next) => {
	try {
		// Get user from data on request
		const bearer = req.get('Authorization');
		const user = await userService.getUser(bearer);

		// Add user to the request-scoped context
		httpContext.set('user', user);

		return next();
	} catch (err) {
		return next(err);
	}
});

Get them from code that doesn't have access to the express req object:

import * as httpContext from 'express-http-context';

// Somewhere deep in the Todo Service
async function createTodoItem(title, content) {
	// Get the user from the request-scoped context
	const user = httpContext.get('user');

	await db.insert({ title, content, userId: user.id });
}

Legacy versions

• For Node <7: npm install --save express-http-context@0
• For Node >=8 <12: npm install --save express-http-context@1

Contributors

• Steve Konves (@skonves)
• Amiram Korach (@amiram)
• Yoni Rabinovitch (@yonirab)
• DontRelaX (@dontrelax)
• William Durand (@willdurand)
• Kristopher Morris (@beeduck)

Interesting in contributing? Take a look at the Contributing Guidlines

Similar packages

Other packages similar to express-http-context

cls-hooked

cls-hooked is a continuation-local storage package that provides a way to maintain context across asynchronous operations. It is more general-purpose compared to express-http-context and can be used outside of Express applications. However, it requires more setup to integrate with Express.

async-local-storage

async-local-storage is a built-in Node.js module that provides an API for maintaining context across asynchronous operations. It is similar to cls-hooked but is part of the Node.js core. It offers a more standardized approach but may require additional boilerplate to use effectively with Express.