Skip to content

Instantly share code, notes, and snippets.

@shrimp2t
Forked from joshnuss/app.js
Created Sep 19, 2019
Embed
What would you like to do?
Express.js role-based permissions middleware
// the main app file
import express from "express";
import loadDb from "./loadDb"; // dummy middleware to load db (sets request.db)
import authenticate from "./authentication"; // middleware for doing authentication
import permit from "./permission"; // middleware for checking if user's role is permitted to make request
const app = express(),
api = express.Router();
// first middleware will setup db connection
app.use(loadDb);
// authenticate each request
// will set `request.user`
app.use(authenticate);
// setup permission middleware,
// check `request.user.role` and decide if ok to continue
app.use("/api/private", permit("admin"));
app.use(["/api/foo", "/api/bar"], permit("owner", "employee"));
// setup requests handlers
api.get("/private/whatever", (req, res) => res.json({whatever: true}));
api.get("/foo", (req, res) => res.json({currentUser: req.user}));
api.get("/bar", (req, res) => res.json({currentUser: req.user}));
// setup permissions based on HTTP Method
// account creation is public
api.post("/account", (req, res) => res.json({message: "created"}));
// account update & delete (PATCH & DELETE) are only available to account owner
api.patch("/account", permit('owner'), (req, res) => res.json({message: "updated"}));
api.delete("/account", permit('owner'), (req, res) => res.json({message: "deleted"}));
// viewing account "GET" available to account owner and account member
api.get("/account", permit('owner', 'employee'), (req, res) => res.json({currentUser: req.user}));
// mount api router
app.use("/api", api);
// start 'er up
app.listen(process.env.PORT || 3000);
// middleware for authentication
export default async function authorize(request, _response, next) {
const apiToken = request.headers['x-api-token'];
// set user on-success
request.user = await request.db.users.findByApiKey(apiToken);
// always continue to next middleware
next();
}
// dummy middleware for db (set's request.db)
export default function loadDb(request, _response, next) {
// dummy db
request.db = {
users: {
findByApiKey: async token => {
switch {
case (token == '1234') {
return {role: 'owner', id: 1234};
case (token == '5678') {
return {role: 'employee', id: 5678};
default:
return null; // no user
}
}
}
};
next();
}
// middleware for doing role-based permissions
export default function permit(...allowed) {
const isAllowed = role => allowed.indexOf(role) > -1;
// return a middleware
return (request, response, next) => {
if (request.user && isAllowed(request.user.role))
next(); // role is allowed, so continue on the next middleware
else {
response.status(403).json({message: "Forbidden"}); // user is forbidden
}
}
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment