c# - 即使数据类型相同，realm.xamarin 也会出现错误 "Data type mismatch"

Question

我正在使用带有 xamarin 表单的 realm.xamarin 0.75，在执行查询时，我收到一个奇怪的错误。查询是

DateTimeOffset fromOffset = new DateTimeOffset(fromDate);
DateTimeOffset toOffset = new DateTimeOffset(toDate);
var config = DependencyService.Get<IDatabase>().GetConfiguration();
using (var realm = Realm.GetInstance(config))
{
    return realm.All<Measurements>()Where(o => o.CreatedDateTime >= fromOffset && o.CreatedDateTime <= toOffset).OrderByDescending(o => o.CreatedDateTime).ToList();
}

错误是:

UNHANDLED EXCEPTION:
06-06 17:46:15.337 I/MonoDroid(26505): Realms.RealmException: Data type mismatch
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.NativeCommon.ExceptionThrower (NativeException exception) [0x00007] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at (wrapper native-to-managed) Realms.NativeCommon:ExceptionThrower (Realms.NativeException)
06-06 17:46:15.337 I/MonoDroid(26505):   at (wrapper managed-to-native) Realms.NativeQuery:timestamp_milliseconds_greater_equal (Realms.QueryHandle,intptr,long)
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.RealmResultsVisitor.AddQueryGreaterThanOrEqual (Realms.QueryHandle queryHandle, System.String columnName, System.Object value) [0x000b6] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.RealmResultsVisitor.VisitBinary (System.Linq.Expressions.BinaryExpression b) [0x0016c] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.ExpressionVisitor.Visit (System.Linq.Expressions.Expression exp) [0x000d2] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.RealmResultsVisitor.VisitCombination (System.Linq.Expressions.BinaryExpression b, System.Action`1 combineWith) [0x00012] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.RealmResultsVisitor.VisitBinary (System.Linq.Expressions.BinaryExpression b) [0x0000c] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.ExpressionVisitor.Visit (System.Linq.Expressions.Expression exp) [0x000d2] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.RealmResultsVisitor.VisitMethodCall (System.Linq.Expressions.MethodCallExpression m) [0x0006a] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.ExpressionVisitor.Visit (System.Linq.Expressions.Expression exp) [0x000ec] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.RealmResultsVisitor.VisitMethodCall (System.Linq.Expressions.MethodCallExpression m) [0x000e6] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.ExpressionVisitor.Visit (System.Linq.Expressions.Expression exp) [0x000ec] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.RealmResults`1[T].CreateResultsHandle () [0x00037] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.RealmResults`1[T].get_ResultsHandle () [0x0000d] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at Realms.RealmResults`1[T].GetEnumerator () [0x00000] in <filename unknown>:0 
06-06 17:46:15.337 I/MonoDroid(26505):   at System.Collections.Generic.List`1[T]..ctor (IEnumerable`1 collection) [0x00073] in /Users/builder/data/lanes/3053/a94a03b5/source/mono/external/referencesource/mscorlib/system/collections/generic/list.cs:104 
06-06 17:46:15.337 I/MonoDroid(26505):   at System.Linq.Enumerable.ToList[TSource] (IEnumerable`1 source) [0x00011] in /Users/builder/data/lanes/3053/a94a03b5/source/mono/external/referencesource/System.Core/System/Linq/Enumerable.cs:835 

我怀疑 DateTimeOffset 可能导致了这个问题。

我在 https://github.com/realm/realm-dotnet 查看了源代码 但找不到任何东西。

Answer 1

我发现了问题。当 RealmObject(在我的例子中是 Measurements)的类没有直接从 RealmObject 继承时，就会发生这种情况。

我的类 Measurements 是从一个类 BaseModel 继承的(我创建这个类是为了内部目的)而这个 BaseModel 类是从 Realm 对象。

当我删除它并使 Measurements 直接从 RealmObject 继承时，我不会抛出异常。

来自 Dimitris Tavlikos 的评论，

Realm Xamarin 不允许模型以任何方式进一步子类化。 CreateObject 泛型方法仅在您将其用于直接从 RealmObject 派生的类时才有效。

https://realm.io/docs/xamarin/latest/#model-inheritance