Realm-java: The getter for a RealmList returns null.

[wbervoets]

Goal

The following query which returns a RealmList sometimes returns null which is unexpected.

realm.where(SearchItem.class)
.equalTo("query", searchQuery)
.findFirst()
.getArticles();

Model object:

public class SearchItem extends RealmObject {

@PrimaryKey
private Long id;

@Required
private String query;

private int priority;

private RealmList<Article> articles;
private RealmList<Folder> folders;
private RealmList<Producer> producers;
private RealmList<Brand> brands;

.... getters/setters

public RealmList<Article> getArticles() {
    return articles;
}

}

Expected Results

Documentation states: The getter for a RealmList will never return null. The returned object is always a list but the length might be zero.

Actual Results

Null value returned

Steps & Code to Reproduce

Version of Realm and tooling

Realm version(s): 3.0.0

Realm sync feature enabled: no

Android Studio version: 2.3

Which Android version and device: OnePlus 3T, Android 7

[beeender]

Is findFirst() returning null? What is the backtrace?

[cmelchior]

Note, It can return null if the object is unmanaged.

[Zhuinden]

are you sure it is not findFirst() that returned null?

[wbervoets]

sorry, it was findFirst() that sometimes returned null because an async write transaction was sometimes already completed and sometimes not

[silviokuehn]

Try and just initialize the list to the resolve this issue that occours on unmanaged object.

private RealmList<RmCategory> subCategories = new RealmList<>();

[minaairsupport]

how is that according to the documentation it should be handled for me

I face the same issue

public class Dog : RealmObject
{
public string Name { get; set; }
}

public class Person : RealmObject
{
// ... other property declarations
public IList Dogs { get; }
}

[Zhuinden]

@minaairsupport your code is for Realm Xamarin, you should ask at https://github.com/realm/realm-dotnet/

[minaairsupport]

Sorry but I think its the same issue

[Zhuinden]

No it's not. It is a completely different binding.

[silviokuehn]

Maybe my last answer from May 2017 goes for Xamarin implementation, too.

[minaairsupport]

I tried by the way and the app crashes , have you tried something else

[Zhuinden]

I'd try reading the crash stack trace for possible error messages that can help deciding what the cause of the error is.

[minaairsupport]

11-05 05:38:28.314 D/Mono ( 6876): Assembly Ref addref CB.Core.Conversion[0xddc89160] -> CB.Core.Common[0xf3cf1e20]: 7
Resolved pending breakpoint at 'ConvertorHelper.cs:84,1' to CB.Core.Entities.FlightListItem CB.Core.Conversion.ConvertorHelper.FlightListItemModelConvertor (CB.Core.Models.FlightListItem item) [0x00160].
11-05 05:38:28.380 F/ ( 6876): * Assertion at /Users/builder/jenkins/workspace/xamarin-android-d15-8/xamarin-android/external/mono/mono/mini/unwind.c:635, condition `cfa_reg != -1' not met
11-05 05:38:28.381 F/libc ( 6876): Fatal signal 6 (SIGABRT), code -6 in tid 7076 (Thread Pool Wor)

[Zhuinden]

Now if I look for this error online, it says that a possible workaround is to use English system locale on the system that compiles the C# code.

[minaairsupport]

could you provide link ?

[Zhuinden]

https://answers.unity.com/questions/1327929/-assertion-at-monominiunwindc620-condition-cfa-reg.html

[minaairsupport]

thanks for link but is it normal to find IList with null and cant add to it

[Zhuinden]

That is not related to the error message you posted at all

[silviokuehn]

Please stop spamming this closed issue with unregarding stuff.

[minaairsupport]

yea this happen when I try silviokuehn answer
private RealmList subCategories = new RealmList<>();
I do the same
private RealmList subCategories => subCategories ?? new RealmList<>();

[Zhuinden]

Bring it over to realm-dotnet.

I will stop answering anything beyond this point.

[minaairsupport]

reported issue https://github.com/realm/realm-dotnet/issues/1787