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我是Cassandra的新手,並使用linq爲我的Cassandra數據庫創建了一個通用存儲庫。對於我的Single()方法,我傳遞了where條件作爲參數。Cassandra:參數類型不匹配
這是我的一個方法:
Single(Expression<Func<T, bool>> exp)
這是我使用查詢卡珊德拉數據庫
public async Task<T> Single(Expression<Func<T, bool>> exp)
{
return await GetTable.Where<T>(exp).FirstOrDefault().ExecuteAsync();
}
這是調用一個方法,該方法的LINQ代碼
public override Task OnConnected()
{
if (Context.User != null)
{
string userName = Context.User.Identity.Name;
this.Groups.Add(userName, Context.ConnectionId);
***** this is the line with the issue ******
Notification notification = Task.Run(() => _notificationRepository.Single(x => x.UserName.Equals(userName))).Result;
if (notification == null)
{
_notificationRepository.CreateInstance(new NotificationUserMapping { Connections = new string[] { Context.ConnectionId }, UserName = Context.User.Identity.Name });
}
else if (!notification.Connections.Contains(Context.ConnectionId))
{
notification.Connections.Add(Context.ConnectionId);
_notificationRepository.Save(notification);
}
}
return base.OnConnected();
}
我不斷收到「參數類型不匹配」的「System.AggregateException」,我很困惑這可能來自哪裏。
的數據庫表列:
id uuid PRIMARY KEY,
connections list<text>,
username text
和C#POCO:
[Table(ExplicitColumns = true)]
public class ConnectionMapping
{
[Column("id")]
public Guid Id { get; set; }
[Column("connections")]
public IList<string> Connections { get; set; }
[Column("username")]
public string UserName { get; set; }
}
和異常:
at System.Linq.Expressions.Expression.Condition(Expression test, Expression ifTrue, Expression ifFalse)
at Cassandra.Mapping.MapperFactory.GetExpressionToGetColumnValueFromRow(ParameterExpression row, CqlColumn dbColumn, Type pocoDestType)
at Cassandra.Mapping.MapperFactory.CreateMapperForPoco[T](RowSet rows, PocoData pocoData)
at Cassandra.Mapping.MapperFactory.CreateMapper[T](RowSet rows)
at Cassandra.Mapping.MapperFactory.<>c__DisplayClass1`1.<GetMapper>b__0(Tuple`2 _)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at Cassandra.Mapping.MapperFactory.GetMapper[T](String cql, RowSet rows)
at Cassandra.Mapping.Mapper.<>c__DisplayClass7`1.<FetchAsync>b__6(Statement s, RowSet rs)
at Cassandra.Mapping.Mapper.<>c__DisplayClass2`1.<>c__DisplayClass4.<ExecuteAsyncAndAdapt>b__1(Task`1 t2)
at Cassandra.Tasks.TaskHelper.DoNext[TIn,TOut](Task`1 task, Func`2 next)
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
at CompanyNamespace.CompanyDomain.NotificationRepository.<SingleByUserName>d__0.MoveNext()
我在想什麼。我對這些文件表示懷疑。 Cassandra和C#之間的映射規則似乎是正確的。
你能展示整個方法嗎?很難說什麼時候你只提供小片段。 – DavidG
您是否還可以爲您收到的'AggregateException'內的異常添加堆棧跟蹤?可能將我們指向正確的方向。 –