Express middleware for adding template bindings #nodejs

viewMiddleware.js

// This is rudimentary view-level middleware for Express.  When
// ServerResponse.render() is called, any middleware methods are
// invoked in the order they were registered.  They are passed the
// request, response, and local template bindings.
//
// For example:
//
//   var connect = require('connect'),
//       app = require('express').createServer();
//
//   app.configure(function() {
//     app.use(connect.cookieDecoder());
//     app.use(connect.session());
//     app.use(viewMiddleware(accountDetails));
//     app.use(app.router);
//   });
//
//   function accountDetails(req, res, locals) {
//     locals.account = req.session.accountId;
//   }
//

var VIEW_MIDDLEWARE = [];

function viewMiddleware(fn) {
  fn && VIEW_MIDDLEWARE.push(fn);
  return function viewMiddleware(req, res, next) {
    res.request = req;
    next();
  };
}

function addBindings(req, res, locals) {
  VIEW_MIDDLEWARE.forEach(function(fn) {
    fn(req, res, locals);
  });
  return locals;
}

var origRender = http.ServerResponse.prototype.render;
http.ServerResponse.prototype.render = function render(name, options, fn) {
  options = options || {};
  options.locals = addBindings(this.request, this, options.locals || {});
  return origRender.call(this, name, options, fn);
};