Question

我有一个遗留应用程序，它包含一个数据库帮助程序类。客户端调用以下函数：

 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

正如您所看到的，上面的函数调用了一个重载的ExecuteReader，它在下面详细说明：

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

我没有看到设置CommandTimeout属性的方法，而没有显着重构代码。从客户端多次调用此函数 - 只有一种情况需要更改commandtimeout。我有一些简单的想法：

1）将commandtimeout设置为实例变量（它不是静态的   类）。这似乎不正确。
  2）使用可选   参数的默认值为：30。

还有其他方法吗？

我意识到我可能应该使用ORM，但这是一个遗留应用程序。

Answer 1

我会使用可选参数，但不使用30秒的硬编码默认值，而是使用默认值-1并添加额外的if语句以检查是否具体提供了值，如果应该覆盖默认超时。

通过这种方式，您仍然可以在连接字符串中设置默认超时，并在需要时使用特定的超时。

需要可选参数

1 个答案: