Overriding field name with @LinkingObjects results in Property could not be found

[dsuresh-ap]

Goal

Create a schema with a many-to-many relationship. Every Release object has a list of Users that it belongs to. Every User has a list of Releases it belongs to.

Actual Results

2019-08-09 13:07:34.552 4848-4848/com.example.realmsampleapp E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.realmsampleapp, PID: 4848
    java.lang.IllegalStateException: Property 'favoriteProcesses' cannot be found.
    (/Users/Nabil/Dev/realm/master4/realm-java/realm/realm-library/src/main/cpp/io_realm_internal_OsObjectSchemaInfo.cpp:119)
        at io.realm.internal.OsObjectSchemaInfo.nativeGetProperty(Native Method)
        at io.realm.internal.OsObjectSchemaInfo.getProperty(OsObjectSchemaInfo.java:174)
        at io.realm.internal.ColumnInfo.addBacklinkDetails(ColumnInfo.java:270)
        at io.realm.com_example_realmsampleapp_models_realmobjects_process_ReleaseRealmObjectRealmProxy$ReleaseRealmObjectColumnInfo.<init>(com_example_realmsampleapp_models_realmobjects_process_ReleaseRealmObjectRealmProxy.java:77)
        at io.realm.com_example_realmsampleapp_models_realmobjects_process_ReleaseRealmObjectRealmProxy.createColumnInfo(com_example_realmsampleapp_models_realmobjects_process_ReleaseRealmObjectRealmProxy.java:690)
        at io.realm.DefaultRealmModuleMediator.createColumnInfo(DefaultRealmModuleMediator.java:71)
        at io.realm.internal.ColumnIndices.getColumnInfo(ColumnIndices.java:84)
        at io.realm.RealmSchema.getColumnInfo(RealmSchema.java:236)
        at io.realm.DefaultRealmModuleMediator.copyOrUpdate(DefaultRealmModuleMediator.java:164)
        at io.realm.Realm.copyOrUpdate(Realm.java:1700)
        at io.realm.Realm.copyToRealmOrUpdate(Realm.java:1091)
        at io.realm.RealmModelListOperator.copyToRealmIfNeeded(RealmList.java:1528)
        at io.realm.RealmModelListOperator.appendValue(RealmList.java:1456)
        at io.realm.ManagedListOperator.append(RealmList.java:1337)
        at io.realm.RealmList.add(RealmList.java:210)
        at com.example.realmsampleapp.utils.FavProcessRealmOperations$addProcessToFavoriteList$1.execute(FavProcessRealmOperations.kt:58)
        at io.realm.Realm.executeTransaction(Realm.java:1493)
        at com.example.realmsampleapp.utils.FavProcessRealmOperations.addProcessToFavoriteList(FavProcessRealmOperations.kt:57)
        at com.example.realmsampleapp.ui.viewmodel.FavoriteProcessFragmentViewModel.onFavoriteProcessClicked(FavoriteProcessFragmentViewModel.kt:34)
        at com.example.realmsampleapp.ui.fragments.FavoriteProcessFragment.onProcessClicked(FavoriteProcessFragment.kt:94)
        at com.example.realmsampleapp.ui.adapter.ProcessViewHolder$bind$1.onCheckedChanged(ProcessViewHolder.kt:24)
        at android.widget.CompoundButton.setChecked(CompoundButton.java:182)
        at android.widget.CompoundButton.toggle(CompoundButton.java:136)
        at android.widget.CompoundButton.performClick(CompoundButton.java:141)
        at android.view.View.performClickInternal(View.java:7299)
        at android.view.View.access$3200(View.java:846)
        at android.view.View$PerformClick.run(View.java:27773)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:6986)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1445)

Steps & Code to Reproduce

Add Release to User's list of releases:

val userPrimaryKey = "key" // Actual key different

        val userRealmObject = realm.where(UserRealmObject::class.java).equalTo("id", userPrimaryKey).findFirst()
        val favoriteProcesses = userRealmObject?.favoriteProcesses
        val isCurrentProcessInFavoriteList = favoriteProcesses?.any { releaseRealmObject ->
            releaseRealmObject.id == processRealmObject.id
        }

        if (isCurrentProcessInFavoriteList == false) {
            realm.executeTransaction {
                favoriteProcesses.add(processRealmObject)
            }
        }

Models

@RealmClass(name = "UserRealmObject", fieldNamingPolicy = RealmNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
open class UserRealmObject : RealmObject() {
  
    @RealmField("favorite_processes") // Linked object fields must match Kotlin names
    var favoriteProcesses: RealmList<ReleaseRealmObject> = RealmList()

    @PrimaryKey
    @RealmField("id")
    var id: String? = null
}

@RealmClass(name = "ReleaseRealmObject", fieldNamingPolicy = RealmNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
open class ReleaseRealmObject : RealmObject() {

    @PrimaryKey
    @RealmField("id")
    var id: Int? = null

    @RealmField("users")
    @LinkingObjects("favoriteProcesses")
    val users: RealmResults<UserRealmObject>? = null
}

To fix prevent the crash, we had to remove fieldNamingPolicy = RealmNamingPolicy.LOWER_CASE_WITH_UNDERSCORES and also
from @RealmField("favorite_processes") from UserRealmObject. Or we could keep fieldNamingPolicy = RealmNamingPolicy.LOWER_CASE_WITH_UNDERSCORES and change @RealmField("favorite_processes") to @RealmField("favoriteProcesses").

It seems like when we override the field name and when Realm attempts to add a backlink, it expects the Kotlin field name in the schema rather than the overriden field name.

Version of Realm and tooling

Realm version(s): plugin 5.13.0

Realm Sync feature enabled: No

Android Studio version: 3.4.2

Android Build Tools version: 29.0.0

Gradle version: 3.4.2

Which Android version and device(s): Samsung S9 9.0

[cmelchior]

This looks like a bug. The @LinkingObjects input should be the names defined in Java, e.g. @LinkingObjects("favoriteProcesses") should work regardless of how and what the underlying Realm field gets mapped to.

I'll take a look.

[bmunkholm]

@cmelchior Can this be closed now with the above fix?

[RealmBot]

➤ Christan Melchior commented:

Fixed by #6582 ( #6582 )