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IWebPartRow Interface

Defines a provider interface for connecting two server controls using a single field of data.

Namespace: System.Web.UI.WebControls.WebParts
Assembly: System.Web (in system.web.dll)

public interface IWebPartRow
public interface IWebPartRow
public interface IWebPartRow
Not applicable.

This interface is designed to be used with Web Parts connections. In a Web Parts connection, two server controls that reside in a WebPartZoneBase zone establish a connection and share data, with one control acting as the consumer and the other control acting as a provider. The mechanism for sharing data in a Web Parts connection is an interface instance, which the provider serves to the consumer by means of a callback method. To establish a connection, the consumer and provider must both work with the same interface type for sharing data. If the consumer does not recognize the interface type sent by the provider, it is still possible to connect the controls by means of a transformer (a WebPartTransformer object) that translates the interface instance sent by the provider into a type that the consumer recognizes. For details on connections, see WebPartConnection and Web Parts Connections Overview.

The IWebPartRow interface is a provider interface included with the Web Parts control set as a standard interface for creating connections based on a data row. You can also create custom interfaces to use with Web Parts connections, but in many data-driven Web applications, it is useful to create connections based on a common field (for details, see the IWebPartField interface), table (for details, see the IWebPartTable interface), or row from the data source. In a typical connection, a WebPart control acting as a provider would implement the IWebPartRow interface and provide an instance of the interface to consumers in a special callback method. For example, the provider might implement an IWebPartRow interface for a row that corresponds to a user in your user information table. Another WebPart control acting as a consumer would define a special method to receive the interface instance, and could then extract the user data, use it to look up additional information about that user's accounts, and display all the information related to that user on the page.

The IWebPartRow interface has two exposed members. The Schema property returns schema information about the data row encapsulated in a PropertyDescriptorCollection object. The GetRowData method declares a method that an implementer (such as a provider control) uses to retrieve the interface instance's row data when the callback method is invoked.

The following code example demonstrates how to create a static connection between two controls using the IWebPartRow interface. The code example has three parts:

  • Source code for two custom WebPart controls that can form a connection using the IWebPartRow interface, with one control acting as the provider, and the other acting as the consumer.

  • A Web page that hosts the controls and declares the static connection in persistence format.

  • A description of what happens when the example code runs.

The first part of the code example is the source code for the two custom controls. First is the code for the provider, which implements the IWebPartRow interface. For simplicity in the example, the provider creates a table with some data rather than connecting to a database. The GetConnectionInterface method serves as the provider's connection point, the callback method that returns the interface instance to the consumer. As for the consumer, it retrieves the interface instance from the provider in its method named SetConnectionInterface, which is marked with a ConnectionConsumer attribute. After retrieving the instance of the interface, the consumer, in its OnPreRender method, calls the implementation of the GetRowData method in the provider, to retrieve the actual data and write it to the page.

For the code example to run, you must compile this source code. You can compile it explicitly and put the resulting assembly in your Web site's Bin folder or the global assembly cache. Alternatively, you can put the source code in your site's App_Code folder, where it will be dynamically compiled at run time. This code example uses dynamic compilation. For a walkthrough that demonstrates how to compile, see Walkthrough: Developing and Using a Custom Server Control.

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Reflection;
using System.Security.Permissions;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;

namespace Samples.AspNet.CS.Controls 
{
  // This sample code creates a Web Parts control that acts as a provider 
  // of row data.
  [AspNetHostingPermission(SecurityAction.Demand,
    Level = AspNetHostingPermissionLevel.Minimal)]
  [AspNetHostingPermission(SecurityAction.InheritanceDemand,
    Level = AspNetHostingPermissionLevel.Minimal)]
  public sealed class RowProviderWebPart : WebPart, IWebPartRow 
	{
    private DataTable _table;
    
    public RowProviderWebPart() 
		{
      _table = new DataTable();

      DataColumn col = new DataColumn();
      col.DataType = typeof(string);
      col.ColumnName = "Name";
      _table.Columns.Add(col);

      col = new DataColumn();
      col.DataType = typeof(string);
      col.ColumnName = "Address";
      _table.Columns.Add(col);

      col = new DataColumn();
      col.DataType = typeof(int);
      col.ColumnName = "ZIP Code";
      _table.Columns.Add(col);

      DataRow row = _table.NewRow();
      row["Name"] = "John Q. Public";
      row["Address"] = "123 Main Street";
      row["ZIP Code"] = 98000;
      _table.Rows.Add(row);
    }

    [ConnectionProvider("Row")]
    public IWebPartRow GetConnectionInterface()
		{
      return new RowProviderWebPart();
    }

    public PropertyDescriptorCollection Schema 
		{
      get 
      {
        return TypeDescriptor.GetProperties(_table.DefaultView[0]);
			}
    }

		public void GetRowData(RowCallback callback)
		{
			callback(_table.Rows);
		}

  } // RowProviderWebPart


  // This sample code creates a Web Parts control that acts as a consumer 
  // of row data.
  [AspNetHostingPermission(SecurityAction.Demand,
    Level = AspNetHostingPermissionLevel.Minimal)]
  [AspNetHostingPermission(SecurityAction.InheritanceDemand,
    Level = AspNetHostingPermissionLevel.Minimal)]  
  public sealed class RowConsumerWebPart : WebPart 
  {
    private IWebPartRow _provider;
		private ICollection _tableData;
	
		private void GetRowData(object rowData)
		{
			_tableData = (ICollection)rowData;
		}

		protected override void OnPreRender(EventArgs e)
		{
			if (_provider != null)
			{
				_provider.GetRowData(new RowCallback(GetRowData));
			}
		}


    protected override void RenderContents(HtmlTextWriter writer) 
    {
      if (_provider != null) 
      {
        PropertyDescriptorCollection props = _provider.Schema;
		    int count = 0;
        if (props != null && props.Count > 0 && _tableData != null) 
        {
            foreach (PropertyDescriptor prop in props) 
			      {
				      foreach (DataRow o in _tableData)
				      {
					      writer.Write(prop.DisplayName + ": " + o[count]);
					      writer.WriteBreak();
					      writer.WriteLine();
					      count = count + 1;
				      }
            }
        }
        else 
        {
          writer.Write("No data");
        }
      }
      else 
      {
        writer.Write("Not connected");
      }
    }

    [ConnectionConsumer("Row")]
    public void SetConnectionInterface(IWebPartRow provider) 
		{
      _provider = provider;
    }

  } // RowConsumerWebPart
    
} // Samples.AspNet.CS.Controls 


The second part of the code example is the Web page that declares the static connection and hosts the controls. Near the top of the page is a Register directive that declares the namespace of the source code contained in the App_Code directory. The connection is declared using an <asp:webpartconnection> element. The custom consumer and provider controls are declared in a <zonetemplate> element within an <asp:webpartzone> element, which is required for them to be able to connect (they must reside within a zone that inherits from the WebPartZoneBase class).

<%@ page language="C#" %>
<%@ Register tagprefix="IRow" 
    Namespace="Samples.AspNet.CS.Controls" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>IRow Test Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
      <asp:webpartmanager ID="WebPartManager1" runat="server">
        <staticconnections>
          <asp:webpartconnection ID="wp1" ProviderID="provider1" 
            ConsumerID="consumer1">
          </asp:webpartconnection>
        </staticconnections>
      </asp:webpartmanager>
       
        <asp:webpartzone ID="WebPartZone1" runat="server">
          <ZoneTemplate>
            <irow:RowProviderWebPart ID="provider1" runat="server" 
              Title="Row Provider Control" />
            <irow:RowConsumerWebPart ID="consumer1" runat="server" 
              Title="Row Consumer Control" />
          </ZoneTemplate>
        </asp:webpartzone>
    </div>
    </form>
</body>
</html>

Load the page in a browser. The consumer control displays the data provided from the specified row, which the provider makes available through an instance of the IWebPartRow interface.

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

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