CODEWITHSUNDEEP
javascriptparse-platformparse-cloud-code
Andrew Robinson
Andrew Robinson

Reputation: 3444

Parse cloud query to get object with closest GeoPoint

I am having issues writing a Parse query to get a Parse object with a GeoPoint that is CLOSEST to the inputted GeoPoint. Currently, the code appears to be returning the most recently created object.

Code:

// check Parse for infections around passed GeoPoint
Parse.Cloud.define("InfectionCheck_BETA", function(request, response) {

var returnCount;

var geoPoint = request.params.geoPoint;
var query = new Parse.Query("InfectedArea");
query.withinMiles("centerPoint", geoPoint, 1); // check for infections within one mile

Parse.Promise.as().then(function() {
    // query for count of infection in area, this is how we get severity
    return query.count().then(null, function(error) {
        console.log('Error getting InfectedArea. Error: ' + error);
        return Parse.Promise.error(error);
    });

}).then(function(count) {
    if (count <= 0) {
        // no infected areas, return 0
        response.success(0);
    }
    returnCount = count;
    return query.first().then(null, function(error) {
        console.log('Error getting InfectedArea. Error: ' + error);
        return Parse.Promise.error(error);
    });

}).then(function(result) {
    // we have the InfectedArea in question, return an array with both
    response.success([returnCount, result]);

}, function(error) {
    response.error(error);
});
});

What I want is for the first() query to return the object with the CLOSEST GeoPoint in the centerPoint key.

I have tried adding query.near("centerPoint", geoPoint) and query.limit(1) to no avail as well.

I have seen iOS PFQueries calling whereKey:nearGeoPoint:withinMiles: that supposably returns sorted based on nearest GeoPoints. Is there a JavaScript equivalent that works like this?

Upvotes: 4

Views: 2901

Answers (1)

Dehli
Dehli

Reputation: 5960

Would you try this? If all the distances are the same, then Parse isn't sorting to the precision that you need.

// check Parse for infections around passed GeoPoint
Parse.Cloud.define("InfectionCheck_BETA", function(request, response) {
    var geoPoint = request.params.geoPoint;
    var query = new Parse.Query("InfectedArea");
    query.near("centerPoint", geoPoint);
    query.limit(10);
    query.find({
        success: function(results) {
            var distances = [];
            for (var i = 0; i < results.length; ++i){
                distances.push(results[i].kilometersTo(geoPoint));
            }
            response.success(distances);
        }, 
        error: function(error) {
            response.error("Error");
        }
    });
});

This results in the ten closest distances.

After chatting, it seems that the reason that the distances weren't being sorted is that Parse only sorts with accuracy of a few centimeters. The differences the user was looking at were less than that.

Upvotes: 6

Related Questions