Async dynamic helper for Express

app.js

var yourAsyncDynamicHelper = require('./yourAsyncDynamicHelper')

app.configure(function(){
  //
  // other middlewares
  //

  app.use(yourAsyncDynamicHelper());

  //
  // other middlewares
  //
});

app.dynamicHelpers({
  data: function(req, res) { return req.your.dynamic.data; }
});

yourAsyncDynamicHelper.js

module.exports = function(options) {

  return function(req, res, next) {
    // do your async stuff here to get your data
    req.your.dynamic.data = 'some async data';
    next();
  }
}