Add more validation to .Filter arguments

CHANGELOG.md

@@ -4,7 +4,7 @@
 * None
 
 ### Fixed
-* None
+* Passing in a deleted object as a substitution argument to `.Filter()` would throw a confusing error with a message starting with `invalid RQL for table`. It now throws a more descriptive error instead. (Issue [#3619](https://github.com/realm/realm-dotnet/issues/3619))
 
 ### Compatibility
 * Realm Studio: 15.0.0 or later.

Realm/Realm/DatabaseTypes/QueryArgument.cs

@@ -19,7 +19,6 @@
 using System;
 using System.Linq;
 using MongoDB.Bson;
-using Realms.Exceptions;
 using Realms.Native;
 
 namespace Realms
@@ -318,9 +317,18 @@ private QueryArgument(RealmValue? realmValue = null, GeoShapeBase? geoValue = nu
             if (RealmValue != null)
             {
                 var primitive = RealmValue.Value;
-                if (primitive.Type == RealmValueType.Object && !primitive.AsIRealmObject().IsManaged)
+                if (primitive.Type == RealmValueType.Object)
                 {
-                    throw new RealmException("Can't use unmanaged object as argument of Filter");
+                    var obj = primitive.AsIRealmObject();
+                    if (!obj.IsManaged)
+                    {
+                        throw new ArgumentException("Can't use unmanaged object as argument of Filter");
+                    }
+
+                    if (!obj.IsValid)
+                    {
+                        throw new ArgumentException("Can't use removed object as argument of Filter");
+                    }
                 }
 
                 var (primitiveValue, handles) = primitive.ToNative();

Tests/Realm.Tests/Database/CollectionTests.cs

@@ -1120,6 +1120,35 @@ public void Results_GetFiltered_SanityTest()
             Assert.That(query.ToArray().All(i => i.Int >= 5));
         }
 
+        [Test]
+        public void Results_Filter_WhenArgumentIsDeletedObject_Throws()
+        {
+            var targetObj = _realm.Write(() =>
+            {
+                var intPropertyObject = _realm.Add(new IntPropertyObject());
+
+                for (var i = 0; i < 10; i++)
+                {
+                    _realm.Add(new ObjectWithObjectProperties
+                    {
+                        StandaloneObject = i % 2 == 0 ? intPropertyObject : null
+                    });
+                }
+
+                return intPropertyObject;
+            });
+
+            var query = _realm.All<ObjectWithObjectProperties>().Filter($"{nameof(ObjectWithObjectProperties.StandaloneObject)} = $0", targetObj);
+            Assert.That(query.Count(), Is.EqualTo(5));
+
+            _realm.Write(() =>
+            {
+                _realm.Remove(targetObj);
+            });
+
+            Assert.Throws<ArgumentException>(() => _realm.All<ObjectWithObjectProperties>().Filter($"{nameof(ObjectWithObjectProperties.StandaloneObject)} = $0", targetObj));
+        }
+
         public readonly struct StringQueryNumericData
         {
             public readonly string PropertyName;