Parse-server: use column value as comparison in query

[florianbepunkt]

Is it possible to use column values for comparison in queries?

Background: I have some kind of dating app, using parse-server as backend. Each user has two fields: a radius field and a geopoint field. In radius field users store in which radius they are looking for other users. I want to to do a two way geo query now…show users other users based on their location and radius setting.

Example: User A and User B are 5 miles apart. User A has a radius he wants to search of 10 miles, user B only has a radius of 1 mile. If user a does a query he should get no results, since user b is within his radius, but he himself (user a) is not within user b's radius.

A one-way check, to see if user B is within user a's radius is simple:
query.withinKilometers('lastLocation', user.get('lastLocation'), user.get('lookingForRadius'));

But I struggle to to the second check to see whether user a is also within user B's radius. For this I would nee to use a column value for comparison in my query.

Pseudo-code would be this
query.withinKilometers('lastLocation', user.get('lastLocation'), 'userRadiusColumnValue');

where userRadiusColumnValue would not be a fixed value but a column value that would change for each row that is queried.

Is this possible in Parse-server? If not, is there another approach to these scenarios where you would need to compare column values in a query?

[bohemima]

General questions on how to use the SDKs doesnt really belong here, try to keep this for actual bug-reports and/or feature requests.

You are probably looking for matchesKeyInQuery

[florianbepunkt]

No, I am not looking for matchesKeyInQuery. Mh… not sure about the place to ask. The documentation refers to Google Group, where it reads that the group is only for archive purposes and instead they refer to Github. Feels like circular dependency injection…

[AmbroiseCollon]

You should do a cloud code function that take care of this for you. Like this :

Parse.Cloud.define('getCloseUsers', function (request, response) {
    var user = request.user
    var query = new Parse.Query(Parse.User)
    query.withinKilometers('lastLocation', user.get('lastLocation'), user.get('lookingForRadius'))
    query.find({
        success: function(foundUsers) {
            var results = []
            for (var i =  0; i < foundUsers.length; i++) {
                var aUser = foundUsers[i]
                var distance = // Calculate distance between aUser last location and current user last location 
                if (distance < aUser.get('lookingForRadius')) {
                    results.append(aUser)
                }
            }
            response.success(results)
        },
        error: function(foundUsers, error) {
            response.error('Unable to query users with error: ' + error.message)
        }
    }
    )
})

Hope it helps. Btw, a good place for this question would be SO.

[florianbepunkt]

Thank you, this is much appreciated.

Regarding the distance calculation. Can I access the distance calculation methods that must exists somewhere in parse server or use haversine formular myself.

Again, thank you.

[danibjor]

You could use the methods on the ParseGeoPoint class.

var dist = myGeoPoint.kilometersTo(otherGeoPoint)

dokumented here

[danibjor]

You could use the methods on the ParseGeoPoint class.
var dist = myGeoPoint.kilometersTo(otherGeoPoint)
https://github.com/ParsePlatform/Parse-SDK-JS/blob/master/src/ParseGeoPoint.js#L147

-------- Opprinnelig melding --------Fra: florianbepunkt [email protected] Dato: 24.10.2016 17:31 (GMT+01:00) Til: ParsePlatform/parse-server [email protected] Emne: Re: [ParsePlatform/parse-server] use column value as comparison in query (#2913)
Thank you, this is much appreciated.

Regarding the distance calculation. Can I access the distance calculation methods that must exists somewhere in parse server or use haversine formular myself.

Again, thank you.

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