PipelineComponent.PreExecute 方法

public:
 virtual void PreExecute();

public virtual void PreExecute();

abstract member PreExecute : unit -> unit
override this.PreExecute : unit -> unit

Public Overridable Sub PreExecute ()

範例

以下範例說明如何定位 中欄位 InputColumnCollection索引。 它們被儲存在一個本地變數中，然後用來 ProcessInput 存取 中的欄位 PipelineBuffer。

int[] bufferColumnIndex;  
public override void PreExecute()  
{  
    IDTSInput100 input = ComponentMetaData.InputCollection[0];  
    bufferColumnIndex = new int[input.InputColumnCollection.Count];  
    for ( int x=0; x < input.InputColumnCollection.Count; x++)  
    {  
        bufferColumnIndex[x] = BufferManager.FindColumnByLineageID( input.Buffer, input.InputColumnCollection[x].LineageID);  
    }  
}  
public override void ProcessInput( int inputID, PipelineBuffer buffer )  
{  
    while( buffer.NextRow() )  
    {  
        for( int x=0; x < bufferColumnIndex.Length(); x++ )  
        {  
            if( !buffer.IsNull(bufferColumnIndex[x]))  
            {  
                // TODO: Access the column data.  
            }  
        }  
    }  
}  

Private bufferColumnIndex As Integer()   

Public Overrides Sub PreExecute()   
 Dim input As IDTSInput100 = ComponentMetaData.InputCollection(0)   
 bufferColumnIndex = New Integer(input.InputColumnCollection.Count - 1) {}   
 Dim x As Integer = 0   
 While x < input.InputColumnCollection.Count  
   bufferColumnIndex(x) = BufferManager.FindColumnByLineageID(input.Buffer, input.InputColumnCollection(x).LineageID)   
   x -= 1  
 End While   
End Sub   

Public Overrides Sub ProcessInput(ByVal inputID As Integer, ByVal buffer As PipelineBuffer)   
 While buffer.NextRow   
   Dim x As Integer = 0   
   While x < bufferColumnIndex.Length   
     If Not buffer.IsNull(bufferColumnIndex(x)) Then   
     End If   
     x -= 1  
   End While   
 End While   
End Sub  

備註

元件開發者應盡可能多地將功能 PreExecute 納入其中，因為對於 ，它被呼叫為每個元件一次，而非每個緩衝 ProcessInput區一次。 元件應透過呼叫 FindColumnByLineageIDBufferManager的方法來定位其輸入與輸出欄位的PipelineBuffer索引。