“Date type mismatch” RealmException in LINQ query

Question

I am having trouble with a LINQ query with Realm Xamarin (C#).

When creating the following classes, and try to fetch all DogModel objects where Person is null, I get a "Date type mismatch" RealmException:

public class DogModel : RealmObject
{
    [PrimaryKey]
    public long Id { get; set; }
    public PersonModel Owner { get; set; }
}

public class PersonModel : RealmObject
{
    [PrimaryKey]
    public long Id { get; set; }
}

var p1 = new PersonModel();
p1.Id = 1;

var d1 = new DogModel();
d1.Id = 1;
d1.Owner = p1;

var d2 = new DogModel();
d2.Id = 2;
d2.Owner = null;

var _realm = Realm.GetInstance();
_realm.Write(() =>
{
    _realm.Add(p1, true);
    _realm.Add(d1, true);
    _realm.Add(d2, true);
});

var data1 = Realm.GetInstance().All<DogModel>()
    .ToList(); // This works

var data2 = Realm.GetInstance().All<DogModel>()
    .Where(x => x.Owner == null)
    .ToList(); // This does not work

In the second LINQ query I would expect to get a list with 1 item (DogModel with Id 2), but instead a "Date type mismatch" RealmException is thrown.

Why does this happen? Is there a way to do it?

Answer 1

Update 11/14/17 : A fix for this has been released with Realm .NET 2.1.0 .

This is indeed a bug in the Realm Xamarin SDK. I've opened an issue to track it: https://github.com/realm/realm-dotnet/issues/1596 . There's no workaround at the moment, but you're right - when it's fixed, it should just work without adding extra properties.