connect-ensure-authorization

This middleware ensures that a user is authorized. If the user is unauthorized, the request returns a JSON error by default or redirects the user with additional configuration.

Table of contents

• Install
• Usage
  • Ensure scope
  • Other ensure functions
  • Custom ensure implementation
  • Custom status code and/or message
  • Redirect instead of return JSON
  • Custom user property
• Usage with Passport

Install

Yarn

$ yarn add connect-ensure-authorization

NPM

$ npm install connect-ensure-authorization

Usage

Ensure scope

In this example, an application has a todos API endpoint. A user must be authorized before accessing this endpoint.

const express = require('express');
const { ensureScope } = require('connect-ensure-authorization');
 
const app = express();
 
// req.user should be like:
// {
//   username: 'bob', <-- dummy data
//   fullName: 'Bob', <-- dummy data
//   scopes: ['todos:read'] <-- used for scope checking
// }
 
app.get('/api/todos', ensureScope('todos:read'), (req, res) => {
  res.json([
    {
      text: 'First todo',
      completed: false,
    },
    {
      text: 'Second todo',
      completed: true,
    }
  ]);
});

If a user is not authorized when attempting to access this API, the request will return the default 403 status code with the default message "Forbidden".

Ensure functions

The following ensure functions are available:

Function	User property
ensureScope	scopes
ensurePermission	permissions
ensureRole	roles
ensureGroup	groups

All functions will check its corresponding user property. The user property should contain an array with strings. The ensure function does an Array.includes check. This default implementation can be modified to your custom requirement.

Custom ensure implementation

The ensure implementation can be overwritten with a custom implementation. This function must return a Promise or a Boolean.

const express = require('express');
const {
  initialize: initializeAuthorization,
  ensureScope 
} = require('connect-ensure-authorization');
 
const app = express();
 
const onEnsureScope = ({ user, scope }) => new Promise((resolve, reject) => {
  if (user.scopes.includes(scope)) {
    resolve();
  } else {
    reject();
  }
});
 
initializeAuthorization({ onEnsureScope });
 
app.get('/api/todos', ensureScope('todos:read'), (req, res) => {
  res.json([
    {
      text: 'First todo',
      completed: false,
    },
    {
      text: 'Second todo',
      completed: true,
    }
  ]);
});

The other ensure implementations are also supported to be overwritten (by passing onEnsurePermission, onEnsureRole and onEnsureGroup).

Custom status code and/or message

The middleware can be configured to return another status code and/or message when unauthorized.

const express = require('express');
const { initialize: initializeAuthorization } = require('connect-ensure-authorization');
 
const app = express();
 
initializeAuthorization({
  statusCode: 418, // default = 403
  message: 'I\'m a teapot!', // default = "Forbidden"
});
 
app.get('/api/todos', ensureScope('todos:read'), (req, res) => {
  res.json([
    {
      text: 'First todo',
      completed: false,
    },
    {
      text: 'Second todo',
      completed: true,
    }
  ]);
});

Redirect instead of return JSON

The following example redirects to /forbidden instead of returning a JSON message.

const express = require('express');
const { initialize: initializeAuthorization } = require('connect-ensure-authorization');
 
const app = express()
 
initializeAuthorization({
  redirectTo: '/forbidden', // default = null
});
 
app.get('/api/todos', ensureScope('todos:read'), (req, res) => {
  res.json([
    {
      text: 'First todo',
      completed: false,
    },
    {
      text: 'Second todo',
      completed: true,
    }
  ]);
});

Custom user property

If you are using Passport, this defaultly sets the req.user after logging in. This can be modified to for example req.account.

const express = require('express');
const { initialize: initializeAuthorization } = require('connect-ensure-authorization');
 
const app = express()
 
initializeAuthorization({
  userProperty: 'account', // default = "user"
});
 
// req.account should be like:
// {
//   accountName: 'bob', // dummy data
//   fullName: 'Bob', // dummy data
//   scopes: ['todos:read'] <-- used for scope checking
// }
 
app.get('/api/todos', ensureScope('todos:read'), (req, res) => {
  res.json([
    {
      text: 'First todo',
      completed: false,
    },
    {
      text: 'Second todo',
      completed: true,
    }
  ]);
});

Usage with Passport

Take a look at the integration test for some inspiration.
I have also created a single file example repository using this module: https://github.com/allardvanderouw/express-api-passport-local-mongo-session-example/blob/master/server.js