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