DetailsViewModeEventHandler Delegate (System.Web.UI.WebControls)

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.NET Framework Class Library
DetailsViewModeEventHandler Delegate

Represents the method that handles the ModeChanging event of a DetailsView control.

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)
Syntax
Visual Basic
Public Delegate Sub DetailsViewModeEventHandler ( _
	sender As Object, _
	e As DetailsViewModeEventArgs _
)
C#
public delegate void DetailsViewModeEventHandler(
	Object sender,
	DetailsViewModeEventArgs e
)
Visual C++
public delegate void DetailsViewModeEventHandler(
	Object^ sender, 
	DetailsViewModeEventArgs^ e
)
F#
type DetailsViewModeEventHandler = 
    delegate of 
        sender:Object * 
        e:DetailsViewModeEventArgs -> unit

Parameters

sender
Type: System.Object
The source of the event.
e
Type: System.Web.UI.WebControls.DetailsViewModeEventArgs
A DetailsViewModeEventArgs that contains the event data.
Remarks

The ModeChanging event is raised when a DetailsView control attempts to change between edit, insert, and read-only mode, but before the mode actually changes. This allows you to provide an event handler that performs a custom routine, such as configuring the DetailsView control for a specific mode or canceling the mode change, whenever this event occurs.

When you create a DetailsViewModeEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.

Examples

The following code example demonstrates how to programmatically add a DetailsViewModeEventHandler delegate to the ModeChanging event of a DetailsView control.

Visual Basic


<%@ Page language="VB"%>

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

  Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)

    ' Create a new DetailsView object.
    Dim customerDetailsView As New DetailsView()

    ' Set the DetailsView object's properties.
    customerDetailsView.ID = "CustomerDetailsView"
    customerDetailsView.DataSourceID = "DetailsViewSource"
    customerDetailsView.AutoGenerateRows = True
    customerDetailsView.AutoGenerateEditButton = True
    customerDetailsView.AllowPaging = True

    Dim keyArray() As String = {"CustomerID"}
    customerDetailsView.DataKeyNames = keyArray

    ' Programmatically register the event-handling method
    ' for the ItemInserted event of a DetailsView control.
    AddHandler customerDetailsView.ModeChanging, AddressOf CustomerDetailsView_ModeChanging

    ' Add the DetailsView object to the Controls collection
    ' of the PlaceHolder control.
    DetailsViewPlaceHolder.Controls.Add(customerDetailsView)

  End Sub

  Sub CustomerDetailsView_ModeChanging(ByVal sender As Object, ByVal e As DetailsViewModeEventArgs)

    ' Use the sender parameter to access the DetailsView
    ' control that raised the event.
    Dim customerDetailsView As DetailsView = CType(sender, DetailsView)

    ' Use the NewMode property to determine the mode to which the 
    ' DetailsView control is transitioning.
    Select Case e.NewMode

      Case DetailsViewMode.Edit
        ' Hide the pager row and clear the Label control
        ' when transitioning to edit mode.
        customerDetailsView.AllowPaging = False
        MessageLabel.Text = ""

      Case DetailsViewMode.ReadOnly
        ' Display the pager row and confirmation message
        ' when transitioning to edit mode.
        customerDetailsView.AllowPaging = True
        If e.CancelingEdit Then

          MessageLabel.Text = "Update canceled."

        Else

          MessageLabel.Text = "Update completed."

        End If

      Case DetailsViewMode.Insert
        ' Cancel the mode change if the DetailsView
        ' control attempts to transition to insert 
        ' mode.
        e.Cancel = True

      Case Else
        MessageLabel.Text = "Unsupported mode."

    End Select

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>DetailsViewModeEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">

      <h3>DetailsViewModeEventHandler Example</h3>

      <!-- Use a PlaceHolder control as the container for the -->
      <!-- dynamically generated DetailsView control.         -->       
      <asp:PlaceHolder id="DetailsViewPlaceHolder"
        runat="server"/>

      <br/><br/>

      <asp:label id="MessageLabel"
        forecolor="Red"
        runat="server"/>

      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the Northwind sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the web.config file.                            -->
      <asp:sqldatasource id="DetailsViewSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address], 
          [City], [PostalCode], [Country] From [Customers]"
        updatecommand="Update [Customers] Set 
          [CompanyName]=@CompanyName, [Address]=@Address, 
          [City]=@City, [PostalCode]=@PostalCode, 
          [Country]=@Country 
          Where [CustomerID]=@CustomerID" 
        connectionstring=
          "<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>

    </form>
  </body>
</html>
C#


<%@ Page language="C#" %>

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

  void Page_Load(Object sender, EventArgs e)
  {

    // Create a new DetailsView object.
    DetailsView customerDetailsView = new DetailsView();

    // Set the DetailsView object's properties.
    customerDetailsView.ID = "CustomerDetailsView";
    customerDetailsView.DataSourceID = "DetailsViewSource";
    customerDetailsView.AutoGenerateRows = true;
    customerDetailsView.AutoGenerateEditButton = true;
    customerDetailsView.AllowPaging = true;
    customerDetailsView.DataKeyNames = new String[1] { "CustomerID" };

    // Programmatically register the event-handling method
    // for the ItemInserted event of a DetailsView control.
    customerDetailsView.ModeChanging += new DetailsViewModeEventHandler(this.CustomerDetailsView_ModeChanging);

    // Add the DetailsView object to the Controls collection
    // of the PlaceHolder control.
    DetailsViewPlaceHolder.Controls.Add(customerDetailsView);

  }

  void CustomerDetailsView_ModeChanging(Object sender, DetailsViewModeEventArgs e)
  {

    // Use the sender parameter to access the DetailsView
    // control that raised the event.
    DetailsView customerDetailsView = (DetailsView)sender;

    // Use the NewMode property to determine the mode to which the 
    // DetailsView control is transitioning.
    switch (e.NewMode)
    {
      case DetailsViewMode.Edit:
        // Hide the pager row and clear the Label control
        // when transitioning to edit mode.
        customerDetailsView.AllowPaging = false;
        MessageLabel.Text = "";
        break;
      case DetailsViewMode.ReadOnly:
        // Display the pager row and confirmation message
        // when transitioning to edit mode.
        customerDetailsView.AllowPaging = true;
        if (e.CancelingEdit)
        {
          MessageLabel.Text = "Update canceled.";
        }
        else
        {
          MessageLabel.Text = "Update completed.";
        }
        break;
      case DetailsViewMode.Insert:
        // Cancel the mode change if the DetailsView
        // control attempts to transition to insert 
        // mode.
        e.Cancel = true;
        break;
      default:
        MessageLabel.Text = "Unsupported mode.";
        break;
    }

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>DetailsViewModeEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">

      <h3>DetailsViewModeEventHandler Example</h3>

      <!-- Use a PlaceHolder control as the container for the -->
      <!-- dynamically generated DetailsView control.         -->       
      <asp:PlaceHolder id="DetailsViewPlaceHolder"
        runat="server"/>

      <br/><br/>

      <asp:label id="MessageLabel"
        forecolor="Red"
        runat="server"/>

      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the Northwind sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the web.config file.                            -->
      <asp:sqldatasource id="DetailsViewSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address], 
          [City], [PostalCode], [Country] From [Customers]"
        updatecommand="Update [Customers] Set 
          [CompanyName]=@CompanyName, [Address]=@Address, 
          [City]=@City, [PostalCode]=@PostalCode, 
          [Country]=@Country 
          Where [CustomerID]=@CustomerID" 
        connectionstring=
          "<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>

    </form>
  </body>
</html>

The following code example demonstrates how to declaratively add a DetailsViewModeEventHandler delegate to the ModeChanging event of a DetailsView control.

Visual Basic


<%@ Page language="VB" autoeventwireup="false" %>

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

  Sub CustomerDetailsView_ModeChanging(ByVal sender As Object, ByVal e As DetailsViewModeEventArgs) Handles CustomerDetailsView.ModeChanging

    ' Use the NewMode property to determine the mode to which the 
    ' DetailsView control is transitioning.
    Select Case e.NewMode

      Case DetailsViewMode.Edit
        ' Hide the pager row and clear the Label control
        ' when transitioning to edit mode.
        CustomerDetailsView.AllowPaging = False
        MessageLabel.Text = ""

      Case DetailsViewMode.ReadOnly
        ' Display the pager row and confirmation message
        ' when transitioning to edit mode.
        CustomerDetailsView.AllowPaging = True
        If e.CancelingEdit Then

          MessageLabel.Text = "Update canceled."

        Else

          MessageLabel.Text = "Update completed."

        End If

      Case DetailsViewMode.Insert
        ' Cancel the mode change if the DetailsView
        ' control attempts to transition to insert 
        ' mode.
        e.Cancel = True

      Case Else
        MessageLabel.Text = "Unsupported mode."

    End Select

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>DetailsViewModeEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">

      <h3>DetailsViewModeEventHandler Example</h3>

      <asp:detailsview id="CustomerDetailsView"
        datasourceid="DetailsViewSource"
        datakeynames="CustomerID"
        autogeneraterows="true"
        autogenerateeditbutton="true" 
        allowpaging="true"
        runat="server">

      </asp:detailsview>

      <br/><br/>

      <asp:label id="MessageLabel"
        forecolor="Red"
        runat="server"/>

      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the Northwind sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the web.config file.                            -->
      <asp:sqldatasource id="DetailsViewSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address], 
          [City], [PostalCode], [Country] From [Customers]"
        updatecommand="Update [Customers] Set 
          [CompanyName]=@CompanyName, [Address]=@Address, 
          [City]=@City, [PostalCode]=@PostalCode, 
          [Country]=@Country 
          Where [CustomerID]=@CustomerID" 
        connectionstring=
          "<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>

    </form>
  </body>
</html>
C#


<%@ Page language="C#" %>

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

  void CustomerDetailsView_ModeChanging(Object sender, DetailsViewModeEventArgs e)
  {

    // Use the NewMode property to determine the mode to which the 
    // DetailsView control is transitioning.
    switch (e.NewMode)
    {
      case DetailsViewMode.Edit:
        // Hide the pager row and clear the Label control
        // when transitioning to edit mode.
        CustomerDetailsView.AllowPaging = false;
        MessageLabel.Text = "";
        break;
      case DetailsViewMode.ReadOnly:
        // Display the pager row and confirmation message
        // when transitioning to edit mode.
        CustomerDetailsView.AllowPaging = true;
        if (e.CancelingEdit)
        {
          MessageLabel.Text = "Update canceled.";
        }
        else
        {
          MessageLabel.Text = "Update completed.";
        }
        break;
      case DetailsViewMode.Insert:
        // Cancel the mode change if the DetailsView
        // control attempts to transition to insert 
        // mode.
        e.Cancel = true;
        break;
      default:
        MessageLabel.Text = "Unsupported mode.";
        break;
    }

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>DetailsViewModeEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">

      <h3>DetailsViewModeEventHandler Example</h3>

      <asp:detailsview id="CustomerDetailsView"
        datasourceid="DetailsViewSource"
        datakeynames="CustomerID"
        autogeneraterows="true"
        autogenerateeditbutton="true" 
        allowpaging="true"
        onmodechanging="CustomerDetailsView_ModeChanging" 
        runat="server">

      </asp:detailsview>

      <br/><br/>

      <asp:label id="MessageLabel"
        forecolor="Red"
        runat="server"/>

      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the Northwind sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the web.config file.                            -->
      <asp:sqldatasource id="DetailsViewSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address], 
          [City], [PostalCode], [Country] From [Customers]"
        updatecommand="Update [Customers] Set 
          [CompanyName]=@CompanyName, [Address]=@Address, 
          [City]=@City, [PostalCode]=@PostalCode, 
          [Country]=@Country 
          Where [CustomerID]=@CustomerID" 
        connectionstring=
          "<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>

    </form>
  </body>
</html>
Version Information

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0
Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Reference

System.Web.UI.WebControls Namespace
DetailsView
DetailsViewModeEventArgs
ModeChanging
OnModeChanging

Other Resources

Events and Delegates