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WebPartTransformerAttribute(Type, Type) 建構函式

定義

初始化 WebPartTransformerAttribute 類別的新執行個體。

public:
 WebPartTransformerAttribute(Type ^ consumerType, Type ^ providerType);
public WebPartTransformerAttribute (Type consumerType, Type providerType);
new System.Web.UI.WebControls.WebParts.WebPartTransformerAttribute : Type * Type -> System.Web.UI.WebControls.WebParts.WebPartTransformerAttribute
Public Sub New (consumerType As Type, providerType As Type)

參數

consumerType
Type

消費者連接點支援之介面的 Type

providerType
Type

提供者連接點支援之介面的 Type

例外狀況

consumerTypeproviderType 未指定。

consumerType等於 providerType

範例

下列程式碼範例示範如何搭配自訂 WebPartTransformer 類別使用 WebPartTransformerAttribute 屬性。 屬性工作表示 RowToStringTransformer 類別可以將 型別 IWebPartRow 的提供者連接點轉換為 型 IString 別的取用者連接點。

此程式碼範例是類別概觀中找到較大範例的 WebPartTransformer 一部分。

// A transformer that transforms a row to a string.
[AspNetHostingPermission(SecurityAction.Demand,
  Level = AspNetHostingPermissionLevel.Minimal)]
[AspNetHostingPermission(SecurityAction.InheritanceDemand,
  Level = AspNetHostingPermissionLevel.Minimal)]
[WebPartTransformer(typeof(IWebPartRow), typeof(IString))]
public class RowToStringTransformer : WebPartTransformer, IString
{

    private IWebPartRow _provider;
    private StringCallback _callback;

    private void GetRowData(object rowData)
    {
        PropertyDescriptorCollection props = _provider.Schema;
        if (props != null && props.Count > 0 && rowData != null)
        {
            string returnValue = String.Empty;
            foreach (PropertyDescriptor prop in props)
            {
                if (prop != props[0])
                {
                    returnValue += ", ";
                }
                returnValue += prop.DisplayName + ": " + prop.GetValue(rowData);
            }
            _callback(returnValue);
        }
        else
        {
            _callback(null);
        }
    }
    
    public override object Transform(object providerData)
    {
        _provider = (IWebPartRow)providerData;
        return this;
    }

    void IString.GetStringValue(StringCallback callback)
    {
        if (callback == null)
        {
            throw new ArgumentNullException("callback");
        }

        if (_provider != null)
        {
            _callback = callback;
            _provider.GetRowData(new RowCallback(GetRowData));
        }
        else
        {
            callback(null);
        }
    }
}
' A transformer that transforms a row to a string.
<AspNetHostingPermission(SecurityAction.Demand, _
   Level:=AspNetHostingPermissionLevel.Minimal)> _
<AspNetHostingPermission(SecurityAction.InheritanceDemand, _
   Level:=AspNetHostingPermissionLevel.Minimal)> _
<WebPartTransformer(GetType(IWebPartRow), GetType(IString))> _
Public Class RowToStringTransformer
    Inherits WebPartTransformer
    Implements IString

    Private _provider As IWebPartRow
    Private _callback As StringCallback

    Private Sub GetRowData(ByVal rowData As Object)
        Dim props As PropertyDescriptorCollection = _provider.Schema

        If ((Not (props Is Nothing)) AndAlso (props.Count > 0) _
          AndAlso (Not (rowData Is Nothing))) Then
            Dim returnValue As String = String.Empty
            For Each prop As PropertyDescriptor In props
                If Not (prop Is props(0)) Then
                    returnValue += ", "
                End If
                returnValue += prop.DisplayName.ToString() + ": " + _
                    prop.GetValue(rowData).ToString()
            Next
            _callback(returnValue)
        Else
            _callback(Nothing)
        End If
    End Sub

    Public Overrides Function Transform(ByVal providerData As Object) As Object
        _provider = CType(providerData, IWebPartRow)
        Return Me
    End Function


    Sub GetStringValue(ByVal callback As StringCallback) _
       Implements IString.GetStringValue
        If (callback Is Nothing) Then
            Throw New ArgumentNullException("callback")
        End If

        If (Not (_provider Is Nothing)) Then
            _callback = callback
            _provider.GetRowData(New RowCallback(AddressOf GetRowData))
        Else
            callback(Nothing)
        End If
    End Sub
End Class

備註

WebPartTransformerAttribute 構函式會設定取用者連接點類型和轉換器的提供者連接點類型。 您可以分別透過 ConsumerType 屬性和 ProviderType 屬性來擷取這些值。

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