Subsonic 3 ActiveRecord 删除/销毁抛出奇怪的异常

Question

我有一个简单的表，其中包含主键（身份）和一些 varchar 类型列。我尝试使用以下语法删除/销毁具有给定主键的记录：

SS3Test.DAL.TestClass.Destroy(x => x.TestId == _testId);

但当调用它时，我得到以下异常：

无法将参数值从 Func`2 转换为 Int32。

堆栈跟踪如下：

System.InvalidOperationException was unhandled
  Message="Failed to convert parameter value from a Func`2 to a Int32."
  Source="SubSonic.Core"
  StackTrace:
       at SubSonic.Query.SqlQuery.Execute()
       at SubSonic.Repository.SubSonicRepository`1.Delete(Object key, IDataProvider provider)
       at SubSonic.Repository.SubSonicRepository`1.Delete(Object key)
       at SS3Test.DAL.TestClass.Destroy(Func`2 expression) in E:\temp\SS3TEst\SS3Test.DAL\ActiveRecord.cs:line 2149
       at SS3Test.Model.TestClass.Delete(Int32 warrantyId, Boolean destroy) in E:\temp\SS3TEst\SS3Test.Model\TestClass.cs:line 84
       at SS3Test.GUI.FrmTestClass.btnDelete_Click(Object sender, EventArgs e) in E:\temp\SS3TEst\SS3Test.GUI\FrmTestClass.cs:line 72
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at SS3Test.GUI.Program.Main() in E:\temp\SS3TEst\SS3Test.GUI\Program.cs:line 21
       at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: System.InvalidCastException
       Message="Failed to convert parameter value from a Func`2 to a Int32."
       Source="System.Data"
       StackTrace:
            at System.Data.SqlClient.SqlParameter.CoerceValue(Object value, MetaType destinationType)
            at System.Data.SqlClient.SqlParameter.GetCoercedValue()
            at System.Data.SqlClient.SqlParameter.Validate(Int32 index, Boolean isCommandProc)
            at System.Data.SqlClient.SqlCommand.BuildParamList(TdsParser parser, SqlParameterCollection parameters)
            at System.Data.SqlClient.SqlCommand.BuildExecuteSql(CommandBehavior behavior, String commandText, SqlParameterCollection parameters, _SqlRPC& rpc)
            at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async)
            at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result)
            at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult result, String methodName, Boolean sendToPipe)
            at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
            at SubSonic.DataProviders.DbDataProvider.ExecuteQuery(QueryCommand qry)
            at SubSonic.Query.SqlQuery.Execute()
       InnerException: System.InvalidCastException
            Message="Object must implement IConvertible."
            Source="mscorlib"
            StackTrace:
                 at System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider)
                 at System.Data.SqlClient.SqlParameter.CoerceValue(Object value, MetaType destinationType)

PS：- 我从这个答案中得到了解决方法，即从数据库中获取具有给定键的对象，然后对其调用删除。它有效，但我想知道为什么我会收到此异常。我还使用 SS 3.0.3（今天下载（2010 年 1 月 26 日））。

Answer 1

它看起来像是一个真正的错误，因为 ActiveRecord Destroy 方法所依赖的 SubSonicRepository 没有 Delete(expression) 重载。

我认为如果您进入 ActiveRecord.tt 模板文件并找到：

    public static void Destroy(Func<<#=tbl.ClassName#>, bool> expression) {
        var repo = GetRepo();
        repo.Delete(expression);
    }

并将 Delete 替换为 DeleteMany ，这将删除给定表达式返回 true 的所有记录（希望只是如果您使用主键，则为一个:)

GC

Answer 2

我不熟悉该库或函数，但错误消息暗示您正在将函数作为参数传递，其中需要 Int32。事实上，您正在将 lambda 函数（“==>”）作为参数传递给 Destroy。因此，首先要检查 Destroy 是否真的需要一个函数，或者一个 Integer。

如果不是这样，请注意 lambda 函数正在重新调整 bool（== 比较的结果），但该错误意味着需要 Int32。您可能必须将 bool 转换为 int，您可以使用 ?: 运算符轻松完成此操作，如下所示：

x => ((x.TestId == _testId) ? 1 : 0)

但是，当然，这两个答案都取决于 Destroy 参数实际期望的内容。