Count query Core Data predicate

Question

i have a entity called schedule that has many alarms (other entity), i want to get only schedules that have less then 30 future alarms. Searching all around i get that query that not works /:

 let predicateFutureAlarms = NSPredicate(format: "(alarms.date > %@).@count < 30", NSDate().timeIntervalSince1970)

(on running time a (lldb) appears on console and appoints to the initialization of that variable)

score 3 · Accepted Answer · edited May 23 '17 at 11:52

3

There are at least two problems:

"(alarms.date > %@).@count < 30" is not a valid predicate syntax.
The %@ placeholder expects an object, but NSDate().timeIntervalSince1970 is a floating point number.

I cannot test it currently, but something like this should work:

let now = NSDate()
let predicate = NSPredicate(format: "SUBQUERY(alarms, $a, $a.date > %@).@count < 30", now)

For each Schedule object, the SUBQUERY(...) evaluates to all related alarms objects which have a date which is greater than now.

See "Predicate Format String Syntax" for a general description of the predicate syntax. The "SUBQUERY" expression is poorly documented, compare the NSExpression class reference or Quick Explanation of SUBQUERY in NSPredicate Expression.

edited May 23 '17 at 11:52

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answered May 05 '16 at 14:27

Martin R

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Thanks!!!, it works, in this case "date" is actually a float, so i change %@ to %f too. – user1779394 May 05 '16 at 14:42
@user1779394: You are welcome! – I had assumed that `date` is a "Date" attribute (which might be more appropriate). – Martin R May 05 '16 at 14:46

Count query Core Data predicate

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