需要可選參數

Question

我有一個遺留應用程序，它包含一個數據庫輔助類。客戶端調用下面的函數：

Public Overloads Shared Function ExecuteReader(ByVal connection As DbConnection, _ 
                  ByVal commandType As CommandType, _ 
                  ByVal commandText As String, _ 
                  ByVal ParamArray commandParameters() As DbParameter) As DbDataReader 
       ' Pass through the call to private overload using a null transaction value 
       Return ExecuteReader(connection, CType(Nothing, DbTransaction), commandType, commandText, commandParameters, dbConnectionOwnership.External) 

End Function 

正如你可以看到上面的函數調用一個重載的ExecuteReader，它的相關詳細如下：

Private Overloads Shared Function ExecuteReader(ByVal connection As DbConnection, _ 
                  ByVal transaction As DbTransaction, _ 
                  ByVal commandType As CommandType, _ 
                  ByVal commandText As String, _ 
                  ByVal commandParameters() As DbParameter, _ 
                  ByVal connectionOwnership As dbConnectionOwnership) As DbDataReader 

      If (connection Is Nothing) Then Throw New ArgumentNullException("connection") 

      Dim mustCloseConnection As Boolean = False 
      Dim cmd As DbCommand 
      ' Create a command and prepare it for execution 
      If TypeOf (connection) Is SqlConnection Then 
       cmd = New SqlCommand 
      ElseIf TypeOf (connection) Is OracleConnection Then 
       cmd = New OracleCommand 
      End If 
      Try 
       ' Create a reader 
       Dim dataReader As DbDataReader 

       PrepareCommand(cmd, connection, transaction, commandType, commandText, commandParameters, mustCloseConnection) 
       ' Call ExecuteReader with the appropriate CommandBehavior 
       If connectionOwnership = dbConnectionOwnership.External Then 
        dataReader = cmd.ExecuteReader() 
       Else 
        dataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection) 
       End If 

       ' Detach the SqlParameters from the command object, so they can be used again 
       Dim canClear As Boolean = True 
       Dim commandParameter As DbParameter 
       For Each commandParameter In cmd.Parameters 
        If commandParameter.Direction <> ParameterDirection.Input Then 
         canClear = False 
        End If 
       Next 

       If (canClear) Then cmd.Parameters.Clear() 

       Return dataReader 
      Catch 
       If (mustCloseConnection) Then connection.Close() 
       Throw 
      End Try 
     End Function 

我看不到設置CommandTimeout屬性不重構的方法代碼顯着。這個函數被客戶端調用很多次 - 只有一個情況需要改變commandtimeout。我有一些快速的想法是：

1）將commandtimeout設置爲一個實例變量（它不是一個靜態的 類）。這似乎不正確，但。
2）使用可選 與參數的默認值：30。

是否有這樣做的任何其他方式？

我意識到我可能應該使用ORM，但這是一個遺留應用程序。

Answer 1

我會去與可選參數，但不是使用的30秒硬編碼的默認值，我會使用的-1默認值，並添加額外的if語句來檢查是否提供了具體的值，如果默認超時應該重寫。

通過這種方式，您仍然可以在連接字符串中設置默認超時，並在需要時使用特定超時。