CodeGo.net>如何使用自定义DbDataReader填充表值参数？

根据MSDN,System.Data.SqlClient支持从DataTable,DbDataReader或IEnumerable< SqlDataRecord>填充表值参数.对象.

我编写了以下代码,这些代码使用IEnumerable< SqlDataRecord>填充了表值参数表对象：

static void Main()
{       
    List<int> idsToSend = ...
    using (SqlConnection connection = new SqlConnection(connectionString))
    {
        connection.Open();    
        SqlCommand command = new SqlCommand(@"SELECT ...
                                              FROM ... 
                                              INNER JOIN @ids mytable ON ...", connection);

        command.Parameters.Add(new SqlParameter("@ids", SqlDbType.Structured)
        {
            TypeName = "int_list_type",
            Direction = ParameterDirection.Input,
            Value = GetSqlDataRecords(idsToSend) //returns IEnumerable<SqlDataRecord> 
        });

        SqlDataReader reader = command.ExecuteReader();
        //consume reader...
    }
}

它运作完美.

MSDN页面显示：

You can also use any object derived from DbDataReader to stream rows
of data to a table-valued parameter.

我想使用自定义DbDataReader来传递行数据.像这样：

public class CustomDataReader : DbDataReader
{
    public CustomDataReader(IEnumerable<int> values)
    {           
    }

    //implementation of other abstract methods and fields required by DbDataReader
    //...
}

我在初始代码示例中更改了以下行：

Value = GetSqlDataRecords(idsToSend)
=>
Value = new CustomDataReader(idsToSend)

如果运行代码,则在执行command.ExecuteReader()时会出现以下异常：

An unhandled exception of type ‘System.NotSupportedException’ occurred
in System.Data.dll Additional information: Specified method is not
supported.

我在CustomDbDataReader类的所有方法和属性上都设置了一个断点：在得到异常之前没有一个方法被调用,因此它可能与DbDataReader的实现无关

编辑：这是根据要求的堆栈跟踪：

   at System.Data.SqlClient.TdsParser.TdsExecuteRPC(SqlCommand cmd, _SqlRPC[] rpcArray, Int32 timeout, Boolean inSchema, SqlNotificationRequest notificationRequest, TdsParserStateObject stateObj, Boolean isCommandProc, Boolean sync, TaskCompletionSource`1 completion, Int32 startRpc, Int32 startParam)
   at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, SqlDataReader ds, Boolean describeParameterEncryptionRequest)
   at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite)
   at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method)
   at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method)
   at System.Data.SqlClient.SqlCommand.ExecuteReader()
   at ConsoleApplication211.Program.Main() in Program.cs:line 51
   at System.AppDomain._nExecuteAssembly(RuntimeAssembly 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.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

解决方法:

您需要实现GetSchemaTable,它没有标记为抽象.

另请参阅：How To Retrieve Column Schema by Using the DataReader GetSchemaTable Method and Visual C# .NET

标签：sqlclient,dbdatareader,table-valued-parameters,c,sql-server
来源： https://codeday.me/bug/20191111/2020872.html