How to perform Realm count query

Question

How can I do a count query on Realm?

for example this is my model

class Dog: Object {
  dynamic var name = ""
}
class Person: Object {
  dynamic var name = ""

  let dogs = List<Dog>()
}

I want to fetch all persons with at least one dog something like

Realm().objects(Person).filter("dogs.@count > 0")

but @count isn't supported as i understand

Answer 1

Yes, Realm still does not support .@count query. You can work around that you modify the Person model to have a count property. Then you update the count property when you append a dog object to the dogs array.

This feature request is tracked by Issue #1166 https://github.com/realm/realm-cocoa/issues/1166

Update

Realm supports @count and other collection queries from v0.96.

Answer 2

Results和List的新聚合表达式（ @count ， @min ， @max ， @sum ， @avg ）的语法如下所示：

realm.objects(Person.self).filter("dogs.@count > 0")