WebPartTransformerAttribute(Type, Type) 构造函数

定义

初始化 WebPartTransformerAttribute 类的新实例。Initializes a new instance of the WebPartTransformerAttribute class.

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)

参数

consumerType
Type

使用者连接点所支持的接口的 TypeThe Type of the interface supported by the consumer connection point.

providerType
Type

提供者连接点所支持的接口的 TypeThe Type of the interface supported by the provider connection point.

例外

未指定 consumerTypeproviderTypeconsumerType or providerType is not specified.

consumerType 等于 providerTypeconsumerType equals providerType.

示例

下面的代码示例演示如何将 WebPartTransformerAttribute 属性与自定义类结合使用 WebPartTransformerThe following code example demonstrates the use of a WebPartTransformerAttribute attribute with a customized WebPartTransformer class. 特性指示 RowToStringTransformer 类可以将类型的提供程序连接点转换 IWebPartRow 为类型的使用者连接点 IStringThe attribute indicates that the RowToStringTransformer class can transform a provider connection point of type IWebPartRow to a consumer connection point of type IString.

此代码示例摘自类概述中的一个更大的示例 WebPartTransformerThis code example is part of a larger example found in the WebPartTransformer class overview.

// 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

注解

WebPartTransformerAttribute构造函数为转换器设置使用者连接点类型和提供程序连接点类型。The WebPartTransformerAttribute constructor sets the consumer connection point type and the provider connection point type for the transformer. 这些值可 ConsumerType 分别通过属性和属性进行检索 ProviderTypeThese values can be retrieved through the ConsumerType property and the ProviderType property, respectively.

适用于