c# - (包装器托管到本地)Realms.NativeTable.get_string的 Realm 查询中的错误

我试图对我的第一个领域数据库做一个简单的查询。尝试访问查询方法返回的对象的属性时出错。
我有两个问题：
一。这个错误是什么意思？我很难理解…
2.我问得对吗？如果没有，我做错什么了？
错误日志：

[mono-rt] Stacktrace:

[mono-rt]   at <unknown> <0xffffffff>

[mono-rt]   at (wrapper managed-to-native) Realms.NativeTable.get_string >(Realms.TableHandle,intptr,intptr,intptr,intptr,bool&) <0x00057>

[mono-rt]   at Realms.RealmObject.GetStringValue (string) <IL 0x0009d, >0x00323>

[mono-rt]   at EasyVending.RCreditCard.get_holderName () <IL 0x0000e, 0x0006f>

[mono-rt]   at EasyVending.RealmManager.getCreditCard () [0x0001c] in /Users/Bernardo/Projects/EasyVending/EasyVending/DataBase/RealmManager.cs:75

[mono-rt]   at EasyVending.Android.CreditCartManagement.OnCreate (Android.OS.Bundle) [0x00111] in /Users/Bernardo/Projects/EasyVending/EasyVending.Android/Activities/CreditCartManagement.cs:89

[mono-rt]   at Android.Support.V4.App.FragmentActivity.n_OnCreate_Landroid_os_Bundle_ (intptr,intptr,intptr) <IL 0x00013, 0x000ff>

[mono-rt]   at (wrapper dynamic-method) object.13add723-97a5-4397-9c8a-e6fc23d98c3c (intptr,intptr,intptr) <IL 0x00017, 0x00043>

[mono-rt]   at (wrapper native-to-managed) object.13add723-97a5-4397-9c8a-e6fc23d98c3c (intptr,intptr,intptr) <IL 0x0001f, 0x00097>

[mono-rt] Attempting native Android stacktrace:

[mono-rt]  at ???+1 [0xbe903ac0]

[mono-rt]  at ???+1 [0x98f50ffc]

=================================================================

Got a SIGSEGV while executing native code. This usually indicates
[mono-rt] a fatal error in the mono runtime or one of the native libraries
[mono-rt] used by your application.
[mono-rt]

[libc] Fatal signal 11 (SIGSEGV), code 1, fault addr 0x97b77168 in tid 9849 (vending_android)

=====================================

public class RCreditCard : RealmObject {
    public string holderName { get; set; }
    public string bandeira { get; set; }
    public string digitos { get; set; }
    public string token { get; set; }
}

public class RealmManager {
    private string databaseName {
        get {
            return "PayBluDatabase.db";
        }
    }
    private string androidPath {
        get {
            return Path.Combine (Environment.GetFolderPath (Environment.SpecialFolder.Personal), databaseName);
        }
    }

    public Realm getRealm() {
        return Realm.GetInstance(androidPath);
    }

    public void closeRealm(Realm realm) {
        realm.Close();
    }

    public Transaction insertCreditCard(EasyVending.CreditCard creditCard) {
        var realm = getRealm();
        using(var transaction = realm.BeginWrite()) {
            var insertedCreditCard = realm.CreateObject<RCreditCard>();

            insertedCreditCard.holderName = creditCard.HolderName;
            insertedCreditCard.bandeira = creditCard.CreditCardBrand;
            insertedCreditCard.digitos = creditCard.MaskedCreditCardNumber;
            insertedCreditCard.token = creditCard.InstantBuyKey;

            transaction.Commit();
            closeRealm(realm);
            return transaction;
        }
    }

    public Transaction removeCreditCard() {
        var realm = getRealm();
        using(var transaction = realm.BeginWrite()) {
            realm.RemoveAll<RCreditCard>();
            transaction.Commit();
            closeRealm(realm);
            return transaction;
        }
    }

    public CreditCard getCreditCard() {
        var realm = getRealm();
        var rCreditCard = realm.All<RCreditCard>().First();
        closeRealm(realm);
        var creditCard = new CreditCard() {
            CreditCardBrand = rCreditCard.bandeira,
            MaskedCreditCardNumber = rCreditCard.digitos,
            HolderName = rCreditCard.holderName
        };
        return creditCard;
    }

    public bool hasCreditCard() {
        bool answer = false;
        var realm = getRealm();
        if(realm.All<RCreditCard>().Count() > 0) {
            answer = true;
        }
        closeRealm(realm);
        return answer;
    }
}

当我试图访问查询返回的rcreditcard对象的任何属性时，会发生错误：

CreditCardBrand = rCreditCard.bandeira,

从

var rCreditCard = realm.All<RCreditCard>().First();

如果问题不够清楚，请告诉我。

最佳答案

问题是，在尝试读取rCreditCard中getCreditCard()的属性之前，您会关闭域。领域对象中的属性是零拷贝的，它们直接访问数据库，因此一旦关闭领域，该对象就会失效。我们应该更好地处理这种情况，目前还不清楚。谢谢你指点我们！
一般来说，除非这些调用在不同的线程上进行，否则您可能不想像以前那样频繁地打开和关闭领域。如果您坚持这样做，您应该将Realm.Close()调用移到事务using范围之外。现在的情况是，如果在事务处理期间有东西抛出，它将被回滚，但您的领域不会像您预期的那样被关闭。
最后，通常不需要有一个“normal”类来映射您的RealmObject类。当然，在你的情况下，可能有一些原因是不明显的。通常，您会直接使用RealmObject类。

关于c# - (包装器托管到本地)Realms.NativeTable.get_string的 Realm 查询中的错误，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/38468403/