Challenge.js

module.exports = function(Challenge) {
  Challenge.on('dataSourceAttached', function(obj) {
    var find = Challenge.find;
    Challenge.find = function(filter, cb) {
      return find.apply(this, arguments);
    };
  });
};

custom_method

module.exports = function(app) {
  var Challenge = app.models.Challenge;
  var Recipe = app.models.Recipe;
  var Restaurant = app.models.Restaurant;
  var playerChallenge = app.models.playerChallenge;
  var find = Challenge.find;
  var cache = {};

  Challenge.find = function(filter, cb) {
    var key = '';
    if (filter) {
      key = JSON.stringify(filter);
    }

    var cachedResults = cache[key];
    if (cachedResults) {
      process.nextTick(function() {
        cb(null, cachedResults);
      });
    } else {
      var result = [];


      Recipe.find().then(function(recipes) {
        result = recipes;
        return Restaurant.find();
      }).then(function(restaurants) {
        return result.concat(restaurants);
      }).then(function(results) {
        find.call(Challenge, function(err, r) {
          if (!err) {
            cache[key] = results;
          }
          console.log(cb);
          cb(err, results);
        });
      });
    }
  };
};