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DataBoundControlAdapter Class

Note: This class is new in the .NET Framework version 2.0.

Customizes the behavior of a DataBoundControl object with which the adapter is associated for specific browser requests.

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

public class DataBoundControlAdapter : WebControlAdapter
public class DataBoundControlAdapter extends WebControlAdapter
public class DataBoundControlAdapter extends WebControlAdapter

A control derived from the DataBoundControl class is bound to a data source and generates its user interface or child control hierarchy by enumerating the items in the data source to which it is bound. DataBoundControl is an abstract base class that defines the common characteristics of all controls that can be bound to a data source, such as the DataGrid and ListBox controls. For more information, see DataBoundControl.

A DataBoundControlAdapter modifies the behavior of a DataBoundControl for a specific browser or class of browsers, or acts as a filter on some capability. Much of the adaptability in rendering behavior can be encapsulated in the specialized classes that derive from the HtmlTextWriter class. Therefore, it is likely that a single adapter can be used for a number of browser class behaviors or that inclusion of the adaptability in the HtmlTextWriter classes can make the use of a control adapter unnecessary.

Each control has explicit mappings to adapters through the .browser definition files, if there are <controlAdapter> entries in these files. Thus, any access to the Adapter property of the DataBoundControl uses the HttpBrowserCapabilities object extracted from the .browser definition files to perform the lookup for the mapping of the adapter to control.

During processing, the .NET Framework intercepts calls to the methods of a control that could be browser specific. If a control adapter is attached, the .NET Framework calls the associated adapter methods. For more information, see ControlAdapter.

The M:System.Web.UI.WebControls.Adapters.DataBoundControlAdapter.PerformDataBinding(System.Collections.IEnumerable) method binds an enumerable collection to the associated DataBoundControl. The Control property returns a strongly typed reference to the DataBoundControl.

The following code examples create and use two derived controls:

  • The MyDataBound class, derived from DataBoundControl, is a simple read-only grid control.

  • The MyDataBoundAdapter class, derived from DataBoundControlAdapter, renders the grid data as a one-dimensional list with row separators, suitable for small screen browsers.

The first code example uses a Web page to declare a MyDataBound control and an instance of ObjectDataSource that provides data in the form of a DataView object.

The second code example contains the derived MyDataBound and MyDataBoundAdapter classes:

  • The MyDataBound class overrides the PerformDataBinding method to save an IEnumerator collection for the data source, and overrides the RenderContents method to render the data source as an HTML <table>.

  • The MyDataBoundAdapter class overrides PerformDataBinding to save the data source to a one-dimensional ArrayList and add row separators. It overrides RenderContents to render the ArrayList as a list of fields separated by <br /> tags.

using System;
using System.Data;
using System.Web;
using System.Web.UI;
using System.Collections;
using System.Security.Permissions;

namespace MyControls
{
    // MyDataBound control is a simple read-only grid control.
    [AspNetHostingPermission(SecurityAction.Demand,
        Level = AspNetHostingPermissionLevel.Minimal)]
    [AspNetHostingPermission(SecurityAction.InheritanceDemand,
        Level = AspNetHostingPermissionLevel.Minimal)]
    public class MyDataBound : System.Web.UI.WebControls.DataBoundControl
    {
        // This is an enumerator for the data source.
        IEnumerator dataSourceEnumerator = null;

        // Render the data source as a table, without row and column headers.
        protected override void RenderContents(
            System.Web.UI.HtmlTextWriter writer)
        {
            // Render the <table> tag.
            writer.RenderBeginTag(HtmlTextWriterTag.Table);

            // Render the table rows.
            while (dataSourceEnumerator.MoveNext())
            {
                // Get the next data row as an object array.
                object[] dataArray = 
                    ((DataRowView)dataSourceEnumerator.Current).Row.ItemArray;

                // Render the <tr> tag.
                writer.RenderBeginTag(HtmlTextWriterTag.Tr);

                // Render the fields of the row.
                for(int col = 0; col<dataArray.GetLength(0) ; col++)
                {
                    //Render the <td> tag, the field data and the </td> tag.
                    writer.RenderBeginTag(HtmlTextWriterTag.Td);
                    writer.Write(dataArray[col]);
                    writer.RenderEndTag();
                }
                // Render the </tr> tag.
                writer.RenderEndTag();
            }
            // Render the </table> tag.
            writer.RenderEndTag();
        }

        // Data binding consists of saving an enumerator for the data.
        protected override void PerformDataBinding(IEnumerable data)
        {
            dataSourceEnumerator = data.GetEnumerator();
        }
    }

    // MyDataBoundAdapter modifies a MyDataBound control to display a
    // grid as a list with row separators.
    [AspNetHostingPermission(SecurityAction.Demand,
        Level = AspNetHostingPermissionLevel.Minimal)]
    [AspNetHostingPermission(SecurityAction.InheritanceDemand,
        Level = AspNetHostingPermissionLevel.Minimal)]
    public class MyDataBoundAdapter :
        System.Web.UI.WebControls.Adapters.DataBoundControlAdapter
    {
        // Returns a strongly-typed reference to the MyDataBound control.
        public new MyDataBound Control
        {
            get
            {
                return (MyDataBound)base.Control;
            }
        }

        // One-dimensional list for the grid data.
        ArrayList dataArray = new ArrayList();

        // Copy grid data to one-dimensional list, add row separators.
        protected override void PerformDataBinding(IEnumerable data)
        {
            IEnumerator dataSourceEnumerator = data.GetEnumerator();

            // Iterate through the table rows.
            while (dataSourceEnumerator.MoveNext())
            {
                // Add the next data row to the ArrayList.
                dataArray.AddRange(
                    ((DataRowView)dataSourceEnumerator.Current).Row.ItemArray);

                // Add a separator to the ArrayList.
                dataArray.Add("----------");
            }
        }

        // Render the data source as a one-dimensional list.
        protected override void RenderContents(
            System.Web.UI.HtmlTextWriter writer)
        {
            // Render the data list.
            for( int col=0; col<dataArray.Count;col++)
            {
                writer.Write(dataArray[col]);
                writer.WriteBreak();
            }
        }
    }
}

The third code example uses a configuration file to specify that no control adapter is to be used with MyDataBound controls for Microsoft Internet Explorer browsers, and that a MyDataBoundAdapter is used with MyDataBound controls for Openwave UP browsers.

  • AspNetHostingPermission  for verifying at compilation time that the immediate caller into DataBoundControlAdapter has this permission. Associated enumerations: LinkDemand, Minimal
  • AspNetHostingPermission  for verifying at load time that the class derived from DataBoundControlAdapter has this permission. Associated enumerations: InheritanceDemand, Minimal

System.Object
   System.Web.UI.Adapters.ControlAdapter
     System.Web.UI.WebControls.Adapters.WebControlAdapter
      System.Web.UI.WebControls.Adapters.DataBoundControlAdapter

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows 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 .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0

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