How to fetch or convert Parse query into array (JavaScript SDK)

Question

I have a column in my Parse database populated with numbers and I'm trying to add them all together to get a total.

I know how to do the adding together if the data returned is a single array, but I can only figure out how to return the numbers as individual objects. This is my code which does that:

        var query = new Parse.Query(Services);
        query.exists("costMonthly");
        query.find({
            success: function (results) {
                for (var i = 0; i < results.length; i++) {
                    var object = results[i];
                    console.log(object.get('costMonthly'));
                }
            },
            error: function (error) {
                alert("Error: " + error.code + " " + error.message);
            }
        });

How would I go about fetching what I want as an array or at least converting what I have into one?

Rob M. · Accepted Answer · 2015-05-10 02:22:22Z

2

It looks like you are trying to sum the costMonthly field. You can use reduce to do this easily:

var query = new Parse.Query(Services);
query.exists("costMonthly");
query.find({
    success: function (results) {
        var sum = results.reduce(function(prev, cur) {
           return prev + cur.get('costMonthly');
        }, 0);
    },
    error: function (error) {
        alert("Error: " + error.code + " " + error.message);
    }
});

If your goal is an array of the costMonthly values, this will work:

var monthlyCosts = results.map(function(item) { 
   return item.get('costMonthly'); 
});

Read more about reduce here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce

edited May 10, 2015 at 2:22

answered May 10, 2015 at 2:15

Rob M.

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Comments

ProllyGeek · Accepted Answer · 2015-05-10 02:17:57Z

You can create a temporary array , and push results though through iteration , not the best solution , but is very useful if you want to manipulate results later :

var costMonthlyArray=[];
 var query = new Parse.Query(Services);
        query.exists("costMonthly");
        query.find({
            success: function (results) {
                for (var i = 0; i < results.length; i++) {
                    var object = results[i];
                    var cost=object.get('costMonthly');
                    costMonthlyArray.push(cost);
                    console.log(cost);
                }
            },
            error: function (error) {
                alert("Error: " + error.code + " " + error.message);
            }
        });

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