How to parse through instances of an object and compare to contents of an array?

Question

I currently have my cloud code setup to return the top two category Ids when parsing eBay's database.

I also have the user system setup on Parse's backend so that each User has multiple instances of the userCategory object associated with their account. Each userCategory instance has a unique categoryId property.

How can I have my eBayCategorySearch function iterate through all a User's userCategory instances, and see if any have a categoryId property that matches the top2 being returned by ebay? I've attempted to do so below, but as far as I can understand, this will only work if userCategory is an array, not multiple instances of an object.

Function that initializes userCategory object when a user signs up:

Parse.Cloud.define("userCategoryCreate", function(request, response) {
    var userCategory = Parse.Object.extend("userCategory");
    var newUserCategory = new userCategory();
    newUserCategory.set("categoryId", "9355");
    newUserCategory.set("minPrice");
    newUserCategory.set("maxPrice");
    newUserCategory.set("itemCondition");
    newUserCategory.set("itemLocation");
    newUserCategory.set("parent", Parse.User.current());
    newUserCategory.save({ 

      success: function (){
        console.log ('userCategory succesfully created!');
        response.success('Request successful');
      },

      error: function (){
        console.log('error!!!');
      response.error('Request failed');
      }

    });
});

eBayCategorySearch function:

Parse.Cloud.define("eBayCategorySearch", function(request, response) {
          url = 'http://svcs.ebay.com/services/search/FindingService/v1';

  Parse.Cloud.httpRequest({
      url: url,
      params: {     
       'OPERATION-NAME' : 'findItemsByKeywords', 
       'SERVICE-VERSION' : '1.12.0',
       'SECURITY-APPNAME' : '*App ID GOES HERE*'
       'GLOBAL-ID' : 'EBAY-US',
       'RESPONSE-DATA-FORMAT' : 'JSON',
       'itemFilter(0).name=ListingType' : 'itemFilter(0).value=FixedPrice',
       'keywords' : request.params.item,

     },
      success: function (httpResponse) {


  // parses results

          var httpresponse = JSON.parse(httpResponse.text);
          var items = [];

          httpresponse.findItemsByKeywordsResponse.forEach(function(itemByKeywordsResponse) {
            itemByKeywordsResponse.searchResult.forEach(function(result) {
              result.item.forEach(function(item) {
                items.push(item);
              });
            });
          });


  // count number of times each unique primaryCategory shows up (based on categoryId), return top two


          var categoryResults = {};

          items.forEach(function(item) {
            var id = item.primaryCategory[0].categoryId;
            if (categoryResults[id]) categoryResults[id]++;
            else categoryResults[id] = 1;
          });

          var top2 = Object.keys(categoryResults).sort(function(a, b) 
            {return categoryResults[b]-categoryResults[a]; }).slice(0, 2);
          console.log('Top categories: ' + top2.join(', '));



  // compare categoryResults to userCategory object

          var userCategory = Parse.User.userCategory;

          var AnyItemsOfCategoryResultsInUserCategory = Object.keys(categoryResults).some(function(item) {
            return userCategory.indexOf(item) > -1;
          });
          console.log('Matches found: ' + AnyItemsOfCategoryResultsInUserCategory);

          var ItemsOfCategoryResultsInUserCategory = Object.keys(categoryResults).filter(function(item) {
            return userCategory.indexOf(item) > -1;
          });
          console.log('User categories that match search: ' + ItemsOfCategoryResultsInUserCategory)


          response.success(AnyItemsOfCategoryResultsInUserCategory);

  },
          error: function (httpResponse) {
              console.log('error!!!');
              response.error('Request failed with response code ' + httpResponse.status);
          }
     });
});

Answer 1

Something like this?

// Ebay ids (Hopefully you can get to this point. If it's a collection, _.map() etc.)
var ebayIDs = ['x1','x2'];

// UserCategoryCollection.models (assuming you're working with a collection .models is where the array of Parse Objects are... here I'm just simply declaring the example)
var userCategoryCollection.models = [{id:'u1',attributes:{categoryId:'a1'}},{id:'u2',attributes:{categoryId:'x1'}},{id:'u3',attributes:{categoryId:'x2'}}]

// How to figure out if there is a match... use Underscore
// Use the find function to iterate through the models, each model being the arg passed
var found = _.find(userCategoryCollection.models, function(userCategory){
    // to the evaluation which will return true if the Parse object prop === a value in the ebayIDs array
    return _.contains(ebayIDs, userCategory.get('categoryId'));
});

// Evaluate
if (found) {
    console.log('hurrah!');
} else {
    console.log('nope');
}

It's a little abstracted from your question but the concept/method should be applicable if I understand your question correctly.