Use ParseQuery to get the first item found from list - parse-platform

Question

I want to query Parse in order to retrieve the first object found in a given list, in the given list's order.
My code looks pretty much like this:
query = getQuery(MyClass.class).whereContainedIn("FieldName", itemList);
networkQuery.getFirstInBackground(...);
What I need, specifically, is to retrieve the first item found in the list, meaning that if I provide it a list of numbers in ascending order, I wish to retrieve the object corresponding with the smallest number possible.
I'm not sure this is how getFirstInBackground() works, I know it fetches a single result, but how can I assure the search is made according to the order of the list I provided as argument?

Answer 1

You have to order your query using the -orderByAscending (or Descending, i can't remember) method. It takes the column name parameter.
So something simple and easy to understand (but I'm sure you've understood already) is to order by ascending "Age" (example), and your first result in the array will be the smallest Age.
Once your query is ordered, just set a -limit to it. It's the number of results the query will return, if you only want the five firsts, set a limit of 5. or 20. The maximum is 1000.
If you also would like to skip the 3 first results because you know they're not interesting (and I'm just elaborating out of your question's scope here), you can use the -skip method, to skip the first X results.
This should do the trick to build your query. Set all those parameters and then execute your query and you'll have correct results.
EDIT : After re-reading your question I'm not sure I'm answering what you're asking. Please elaborate if I'm not.

Answer 2

Find the minimum value in itemList yourself, and qualify the query with that using equalTo.
// is this javascript? if so, underscorejs is very useful
var _ = require('underscore');
var minItem = _.min(itemList); // you can add an optional iteratee function that can minimize any computation over the list
query.equalTo("FieldName", minItem);
query.getFirstInBackground(...);
Edit
Parse.Query ordering applies only to sortable types, like strings and numbers. The ordering hoped for in the question is on the min() value of an array attribute. If such a thing were available, then a getFirst query would work.
What you need can still be done with find(). Since a small number of rows will have FieldName values contained in itemList, you can just do a find() and pick out the minimum from those few results...
query.find().then(function(results) {
return _.min(results, function(result) {
return result.get("FieldName");
});
});