Batch find for ember data - it waits for multiple calls on the same run loop and performs a single request on the API

ember-batch-find.js

// Batch find for Ember Data. It will coerce all the finds on the same run loop
// and execute a single batch find for all the records. It mimics the find
// semantics.
//
// Example usage:
//
//     var user1 = store.find('user', 1);
//     var user2 = store.find('user', 2);
//
//     user1.then(function(user){
//       console.log(user1.get('firstName'));
//     });
//
//     user2.then(function(user){
//       console.log(user2.get('firstName');
//       // circumstancially, this will be available as well:
//       console.log(user1.get('firstName');
//     });
//
(function(exports){
  var findQueues = {};

  var FindPromise = Ember.ObjectProxy.extend(Ember.PromiseProxyMixin);

  var findMany = function(store, type, ids){
    return new Ember.RSVP.Promise(function(resolve){
      store.find(type, {ids: ids}).then(function(){
        resolve();
      });
    });
  };

  var batchFind = function(type, id){
    var store = this;

    var promise = new Ember.RSVP.Promise(function(resolve){
      var cachedModel = store.getById(type, id);
      if(cachedModel){
        resolve(cachedModel);
      }else{
        if(!findQueues[type]) findQueues[type] = [];
        findQueues[type].push([id, resolve]);

        Ember.run.scheduleOnce('afterRender', store, flushFindQueues);
      }
    });

    return FindPromise.create({
      content: Ember.Object.create({id: id}),
      promise: promise
    });
  };

  var mapIndex = function(array, index){
    return array.map(function(element){
      return element[index];
    });
  };

  var flushQueue = function(store, key, tasks){
    var ids = mapIndex(tasks, 0);

    findMany(store, key, ids).then(function(){
      tasks.forEach(function(task){
        var record = store.getById(key, task[0]);
        task[1].call(this, record);
      });
    });

    findQueues[key] = [];
  };

  var flushFindQueues = function(){
    var store = this;

    for (var key in findQueues) {
      if(findQueues.hasOwnProperty(key)){
        var tasks = findQueues[key];
        flushQueue(store, key, tasks);
        findQueues[key] = [];
      }
    }
  };

  exports.Store.reopen({
    batchFind: batchFind
  });
})(App);