Parse.com : Query with the result from another query

Question

I have an application where posts have a limited lifetime. Every like adds life to the post.

in my table I have a field initialDeletionDate and a counter that tracks the number of likes. In my newsfeed, I'm trying to query objects, but I only want to get objects that still alive.

So basically, what I want to do is get all object where:

initialDeletionDate + counter*time < [NSDate date]
//time = 1200 sec

something like...:

[query whereKey:@"initialDeletionDate" lessThan:[NSDate date] - "key: counter"];

How can I do this?

Timothy Walters · Accepted Answer · 2014-07-01 23:29:33Z

1

I would recommend adding a 3rd field to your class that has the final deletion date. You could either update your client code or create a cloud method that sets the value of this date to initialDeletionDate + (counter*1200).

Then when you query you can just ask for records that haven't reached their calculated deletion date yet:

[query whereKey:@"calculatedDeletionDate" greaterThan:[NSDate date]];

Update:

Here's a starting point for a before-save Cloud Function.

// include Moment library for easier date handling
var moment = require("moment");

Parse.Cloud.beforeSave("YourClassNameHere", function(request, response) {
    var yourClass = request.object;

    if (yourClass.dirty("initialDeletionDate")
        || yourClass.dirty("counter"))
    {
        // recalculate
        var initialDate = yourClass.get("initialDeletionDate");
        var counter = yourClass.get("counter");
        // use Moment library to manipulate the date
        var calculatedDate = moment(initialDate)
            .add('minutes', counter * 2)
            .toDate();
        yourClass.set("calculatedDeletionDate", calculatedDate);
    }
    response.success();
}

edited Jul 1, 2014 at 23:29

answered Jul 1, 2014 at 21:38

Timothy Walters

16.9k2 gold badges44 silver badges49 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Sancho Sanchez Over a year ago

thanks for your answer Timothy. Do I call the cloudcode method from the iOs client? If multiple users increment the counter at the same time will the "calculatedDeletionDate" be accurate?

Timothy Walters Over a year ago

@SanchoSanchez If you create a before-save Cloud Function then it will be able to keep the calculation updated properly. I'll add a sample to my answer for you

Sancho Sanchez Over a year ago

that is really nice of you !

Collectives™ on Stack Overflow

Parse.com : Query with the result from another query

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related