How to check if Object already exist? - node.js

Question

I am importing products from a product feed. A product has a designer and a category and I made them separate tables (Parse classes).
The problem now is that I need to check if a category or designer already exists so I don't need to create it.
Currently I am not checking it, causing many duplicates in my DB. If I checked in DB, it would be asynchronous but I actually need it to be somehow sequential(serialized).. Any ideas?
for (var i=1;i<productsFromFeed.length;i++){
productId = parseInt(productsFromFeed[i][1]);
if (productId > lastProduct.get("productId")){
console.log("Product is new: " + productId);
var Designer = Parse.Object.extend("Designer");
var Product = Parse.Object.extend("Product");
var Category = Parse.Object.extend("Category");
var designer = new Designer();
designer.set("name", productsFromFeed[i][4]);
designer.set("designerId", parseInt(productsFromFeed[i][5]));
var category = new Category();
category.set("name", productsFromFeed[i][6]);
category.set("categoryId", parseInt(productsFromFeed[i][7]));
var newProduct = new Product();
newProduct.set("productName", productsFromFeed[i][0]);
newProduct.set("productId", parseInt(productsFromFeed[i][1]));
newProduct.set("designer", designer);
newProduct.set("category", category);
objects.push(newProduct);
} else {
console.log("Product already exists: " + productId);
}
}

Answer 1

It doesn't need to be serial, you just need to deal with the asynchronous nature of what you're trying to do - using promises.
You could run a query to find everything in advance and locally cache them, that's only useful if you're doing a bulk import, your code does look like a small bulk import but it isn't clear if this will be an efficient approach.
In your case just run your queries and use promises to chain each logical stage together. Note that for your loop you can put the resulting promises into an array and wait till they're all complete.