CODEWITHSUNDEEP
androidkotlinrealm
tendai
tendai

Reputation: 1251

Query the size of a Realm Class Sub object - Kotlin

How do i query the size of a realm object that is within another realm object

I have two realm classes Competition & User. User is a realm class also contained in Competition:

open class Competition (@PrimaryKey var competitionId: String?=null,
                      var user: User? =null): RealmObject()

open class User(@PrimaryKey var userId: String?=null,
                      var name: String? =null): RealmObject()

At some point, i would like to get the size of User within a specific competitionId in Competition and i'm having a challenge with what i thought would be trivial

Here is what i have tried

var userObj = realm.where<Competition>().equalTo(
                "competitionId", competitionId
            ).findFirst().user.realm.where<User>().findAll().size

This gives me a

kotlin.KotlinNullPointerException

Stacktrace:

2019-03-12 16:03:25.112 22028-22028/co.keepnet.bass W/System.err: kotlin.KotlinNullPointerException
2019-03-12 16:03:25.113 22028-22028/co.keepnet.bass W/System.err:     at co.keepnet.bass.ui.MainActivity$onClick$1.execute(MainActivity.kt:41)
2019-03-12 16:03:25.113 22028-22028/co.keepnet.bass W/System.err:     at io.realm.Realm.executeTransaction(Realm.java:1431)
2019-03-12 16:03:25.113 22028-22028/co.keepnet.bass W/System.err:     at co.keepnet.bass.ui.MainActivity.onClick(MainActivity.kt:37)
2019-03-12 16:03:25.113 22028-22028/co.keepnet.bass W/System.err:     at co.keepnet.bass.data.adapter.CompetitionsAdapter$onBindViewHolder$1.onClick(CompetitionsAdapter.kt:75)
2019-03-12 16:03:25.113 22028-22028/co.keepnet.bass W/System.err:     at android.view.View.performClick(View.java:6897)
2019-03-12 16:03:25.113 22028-22028/co.keepnet.bass W/System.err:     at android.view.View$PerformClick.run(View.java:26101)
2019-03-12 16:03:25.113 22028-22028/co.keepnet.bass W/System.err:     at android.os.Handler.handleCallback(Handler.java:789)
2019-03-12 16:03:25.113 22028-22028/co.keepnet.bass W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:98)
2019-03-12 16:03:25.113 22028-22028/co.keepnet.bass W/System.err:     at android.os.Looper.loop(Looper.java:164)
2019-03-12 16:03:25.114 22028-22028/co.keepnet.bass W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:6944)
2019-03-12 16:03:25.114 22028-22028/co.keepnet.bass W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
2019-03-12 16:03:25.114 22028-22028/co.keepnet.bass W/System.err:     at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:327)
2019-03-12 16:03:25.114 22028-22028/co.keepnet.bass W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1374)

Upvotes: 1

Views: 622

Answers (1)

EpicPandaForce
EpicPandaForce

Reputation: 81539

I mean, it is fairly trivial, if you use Realm's features to your advantage (3.5.0+, I think).

open class User(): RealmObject() {
    @PrimaryKey var userId: String? = null

    var name: String? = null

    @LinkingObjects("user")
    val userOfCompetitions: RealmResults<Competition>? = null
}

Then

val userCount = realm.where<User>()
                     .equalTo("userOfCompetitions.competitionId", competitionId)
                     .count()

Upvotes: 2

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