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FormViewModeEventHandler Delegate

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

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

public delegate void FormViewModeEventHandler(
	Object sender,
	FormViewModeEventArgs e
)

Parameters

sender
Type: System.Object

The source of the event.

e
Type: System.Web.UI.WebControls.FormViewModeEventArgs

A FormViewModeEventArgs that contains the event data.

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

When you create a FormViewModeEventHandler 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.

The following example demonstrates how to programmatically add a FormViewModeEventHandler delegate to the ModeChanging event of a FormView control.

Security noteSecurity Note:

The control in this example has a text box that accepts user input, which is a potential security threat. By default, ASP.NET Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview.

<%@ Page language="C#" %>
<%@ import namespace="System.Data"%>

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

  // To dynamically create a template for a FormView control, 
  // you must create a custom template class to represent  
  // the template. This template class represents the item 
  // template for a FormView control. 
  private sealed class EmployeeItemTemplate : ITemplate
  {

    // When implementing the ITemplate interface, you must 
    // implement the InstantiateIn method. The FormView 
    // control calls this method to create the template's  
    // content.  
    void ITemplate.InstantiateIn(Control container)
    {
      // Create the child controls contained in the template. 
      // For this example, the item template displays the 
      // FirstName and LastName fields from the data source. 
      // To support data binding, create event handlers  
      // for the DataBinding event of each child control. 
      // The event handlers must bind the appropriate value  
      // to each control.
      Label firstNameLabel = new Label();
      firstNameLabel.ID = "FirstNameLabel";
      firstNameLabel.DataBinding += new EventHandler(FirstNameLabel_DataBinding);

      LiteralControl nameLineBreak = new LiteralControl("<br/>");
      LiteralControl buttonLineBreak = new LiteralControl("<br/>");

      Label lastNameLabel = new Label();
      lastNameLabel.ID = "LastNameLabel";
      lastNameLabel.DataBinding += new EventHandler(LastNameLabel_DataBinding);

      Button editButton = new Button();
      editButton.ID = "EditButton";
      editButton.CommandName = "Edit";
      editButton.Text = "Edit";

      // Add the controls to the Controls collection of the  
      // container control.
      container.Controls.Add(firstNameLabel);
      container.Controls.Add(nameLineBreak);
      container.Controls.Add(lastNameLabel);
      container.Controls.Add(buttonLineBreak);
      container.Controls.Add(editButton);

    }

    // This event handler binds the value of the FirstName field 
    // to the FirstNameLabel Label control displayed in the template. 
    private void FirstNameLabel_DataBinding(Object sender, EventArgs e)
    {
      // Use the sender parameter to retrieve the Label control 
      // being bound to data.
      Label firstNameLabelControl = (Label)sender;

      // Retrieve the value to bind to the Label control. First, 
      // use the NamingContainer property to retrieve the parent  
      // control of the Label control. In this example, the parent  
      // control is the FormView control.
      FormView formViewContainer = (FormView)firstNameLabelControl.NamingContainer;

      // Get the data item bound to the FormView control.
      DataRowView rowView = (DataRowView)formViewContainer.DataItem;

      // Use the data item to retrieve the value of the FirstName field. 
      // Set the Text property of the Label control to this value.        
      firstNameLabelControl.Text = rowView["FirstName"].ToString();
    }

    // This event handler binds the value of the LastName field 
    // to the LastNameLabel Label control displayed in the template. 
    private void LastNameLabel_DataBinding(Object sender, EventArgs e)
    {
      // Use the sender parameter to retrieve the Label control 
      // being bound to data.
      Label lastNameLabelControl = (Label)sender;

      // Retrieve the value to bind to the Label control. First, 
      // use the NamingContainer property to retrieve the parent  
      // control of the Label control. In this example, the parent  
      // control is the FormView control.
      FormView formViewContainer = (FormView)lastNameLabelControl.NamingContainer;

      // Get the data item bound to the FormView control.
      DataRowView rowView = (DataRowView)formViewContainer.DataItem;

      // Use the data item to retrieve the value of the LastName field. 
      // Set the Text property of the Label control to this value.         
      lastNameLabelControl.Text = rowView["LastName"].ToString();
    }

  }

  // This template class represents the edit item 
  // template for a FormView control. 
  private sealed class EmployeeEditItemTemplate : ITemplate
  {

    void ITemplate.InstantiateIn(Control container)
    {
      // Create the child controls contained in the template. 
      // The edit item template should contain the input  
      // controls for the user to edit a record.
      TextBox firstNameTextBox = new TextBox();
      firstNameTextBox.ID = "FirstNameTextBox";

      LiteralControl nameLineBreak = new LiteralControl("<br/>");
      LiteralControl buttonLineBreak = new LiteralControl("<br/>");

      TextBox lastNameTextBox = new TextBox();
      lastNameTextBox.ID = "LastNameTextBox";

      Button updateButton = new Button();
      updateButton.ID = "UpdateButton";
      updateButton.CommandName = "Update";
      updateButton.Text = "Update";

      Button cancelButton = new Button();
      cancelButton.ID = "CancelButton";
      cancelButton.CommandName = "Cancel";
      cancelButton.Text = "Cancel";

      // Add the controls to the Controls collection of the  
      // container control.
      container.Controls.Add(firstNameTextBox);
      container.Controls.Add(nameLineBreak);
      container.Controls.Add(lastNameTextBox);
      container.Controls.Add(buttonLineBreak);
      container.Controls.Add(updateButton);
      container.Controls.Add(cancelButton);

    }
  }

  void Page_Load(Object sender, EventArgs e)
  {

    // Create a new FormView object.
    FormView employeesFormView = new FormView();

    // Set the FormView object's properties.
    employeesFormView.ID = "EmployeesFormView";
    employeesFormView.DataSourceID = "EmployeeSource";
    employeesFormView.AllowPaging = true;
    employeesFormView.HeaderText = "Employee Name";
    employeesFormView.DataKeyNames = new String[1] { "EmployeeID" };

    // Programmatically register the event handlers for the  
    // the FormView control.
    employeesFormView.ModeChanging += new FormViewModeEventHandler(EmployeeFormView_ModeChanging);
    employeesFormView.ItemUpdating += new FormViewUpdateEventHandler(EmployeeFormView_ItemUpdating);

    // Create the dynamic templates using the custom template classes.
    employeesFormView.ItemTemplate = new EmployeeItemTemplate();
    employeesFormView.EditItemTemplate = new EmployeeEditItemTemplate();

    // Add the FormView object to the Controls collection 
    // of the PlaceHolder control.
    FormViewPlaceHolder.Controls.Add(employeesFormView);

  }

  void EmployeeFormView_ItemUpdating(Object sender, FormViewUpdateEventArgs e)
  {

    // Because the FormView control is dynamically generated,  
    // the NewValues collection must be programmatically populated 
    // with the values for the record to update. 

    // Use the sender argument to retrieve the FormView 
    // control that raised the event.
    FormView employeeFormView = (FormView)sender;

    // Retrieve the data row from the FormView control.
    FormViewRow row = employeeFormView.Row;

    // Retrieve the TextBox controls that contain the updated values  
    // entered by the user. 
    TextBox firstNameTextBox = (TextBox)row.FindControl("FirstNameTextBox");
    TextBox lastNameTextBox = (TextBox)row.FindControl("LastNameTextBox");

    if (firstNameTextBox != null && lastNameTextBox != null)
    {
      // Add the new values to the NewValues collections.
      e.NewValues.Add("FirstName", firstNameTextBox.Text);
      e.NewValues.Add("LastName", lastNameTextBox.Text);
    }

  }

  void EmployeeFormView_ModeChanging(Object sender, FormViewModeEventArgs e)
  {

    // Use the sender argument to retrieve the FormView 
    // control that raised the event.
    FormView employeeFormView = (FormView)sender;

    // Use the NewMode property to determine the mode to which the  
    // FormView control is transitioning. 
    switch (e.NewMode)
    {
      case FormViewMode.Edit:
        // Hide the pager row and clear the Label control 
        // when transitioning to edit mode.
        employeeFormView.AllowPaging = false;
        MessageLabel.Text = "";
        break;
      case FormViewMode.ReadOnly:
        // Display the pager row and confirmation message 
        // when transitioning to edit mode.
        employeeFormView.AllowPaging = true;
        if (e.CancelingEdit)
        {
          MessageLabel.Text = "Update canceled.";
        }
        else
        {
          MessageLabel.Text = "Update completed.";
        }
        break;
      case FormViewMode.Insert:
        // Cancel the mode change if the FormView 
        // 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>FormView Example</title>
</head>
<body>
    <form id="form1" runat="server">

      <h3>FormView Example</h3>

      <!-- Use a PlaceHolder control as the container for the -->
      <!-- dynamically generated FormView control.            -->       
      <asp:placeholder id="FormViewPlaceHolder"
        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="EmployeeSource"
        selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
        updatecommand="Update [Employees] Set [LastName]=@LastName, [FirstName]=@FirstName Where [EmployeeID]=@EmployeeID"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>

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

The following example demonstrates how to declaratively add a FormViewModeEventHandler delegate to the ModeChanging event of a FormView control.

Security noteSecurity Note:

The control in this example has a text box that accepts user input, which is a potential security threat. By default, ASP.NET Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview.

<%@ 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 EmployeeFormView_ModeChanging(Object sender, FormViewModeEventArgs e)
  {

    // Use the NewMode property to determine the mode to which the  
    // FormView control is transitioning. 
    switch (e.NewMode)
    {
      case FormViewMode.Edit:
        // Hide the pager row and clear the Label control 
        // when transitioning to edit mode.
        EmployeeFormView.AllowPaging = false;
        MessageLabel.Text = "";
        break;
      case FormViewMode.ReadOnly:
        // Display the pager row and confirmation message 
        // when transitioning to edit mode.
        EmployeeFormView.AllowPaging = true;
        if (e.CancelingEdit)
        {
          MessageLabel.Text = "Update canceled.";
        }
        else
        {
          MessageLabel.Text = "Update completed.";
        }
        break;
      case FormViewMode.Insert:
        // Cancel the mode change if the FormView 
        // 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>FormViewModeEventArgs Example</title>
</head>
<body>
    <form id="form1" runat="server">

      <h3>FormViewModeEventArgs Example</h3>

      <asp:formview id="EmployeeFormView"
        datasourceid="EmployeeSource"
        allowpaging="true"
        datakeynames="EmployeeID"
        emptydatatext="No employees found."
        onmodechanging="EmployeeFormView_ModeChanging"  
        runat="server">

        <itemtemplate>
          <table>
            <tr>
              <td rowspan="6">
                <asp:image id="EmployeeImage"
                  imageurl='<%# Eval("PhotoPath") %>'
                  alternatetext='<%# Eval("LastName") %>' 
                  runat="server"/>
              </td>
              <td colspan="2">
                  &nbsp; 
              </td>
            </tr>
            <tr>
              <td>
                <b>Name:</b>
              </td>
              <td>
                <%# Eval("FirstName") %> <%# Eval("LastName") %>
              </td>
            </tr>
            <tr>
              <td>
                <b>Title:</b>
              </td>
              <td>
                <%# Eval("Title") %>
              </td>
            </tr>
            <tr>
              <td>
                <b>Hire Date:</b>                 
              </td>
              <td>
                <%# Eval("HireDate","{0:d}") %>
              </td>
            </tr>
            <tr style="height:150" valign="top">
              <td>
                <b>Address:</b>
              </td>
              <td>
                <%# Eval("Address") %><br/>
                <%# Eval("City") %> <%# Eval("Region") %>
                <%# Eval("PostalCode") %><br/>
                <%# Eval("Country") %>   
              </td>
            </tr>
            <tr>
              <td colspan="2">
                <asp:linkbutton id="Edit"
                  text="Edit"
                  commandname="Edit"
                  runat="server"/> 
              </td>
            </tr>
          </table>       
        </itemtemplate>
        <edititemtemplate>
          <table>
            <tr>
              <td rowspan="6">
                <asp:image id="EmployeeEditImage"
                  imageurl='<%# Eval("PhotoPath") %>'
                  alternatetext='<%# Eval("LastName") %>' 
                  runat="server"/>
              </td>
              <td colspan="2">
                  &nbsp; 
              </td>
            </tr>
            <tr>
              <td>
                <b><asp:Label runat="server" 
                  AssociatedControlID="FirstNameUpdateTextBox" 
                  Text="Name" />:</b>
              </td>
              <td>
                <asp:textbox id="FirstNameUpdateTextBox"
                  text='<%# Bind("FirstName") %>'
                  accesskey="n" tabindex="1" runat="server"/>
                <asp:textbox id="LastNameUpdateTextBox"
                  text='<%# Bind("LastName") %>'
                  accesskey="l" tabindex="2" runat="server"/>
              </td>
            </tr>
            <tr>
              <td>
                <b><asp:Label runat="server" 
                  AssociatedControlID="TitleUpdateTextBox" 
                  Text="Title" />:</b>
              </td>
              <td>
                <asp:textbox id="TitleUpdateTextBox"
                  text='<%# Bind("Title") %>'
                  accesskey="t" tabindex="3" runat="server"/> 
              </td>
            </tr>
            <tr>
                <b><asp:Label runat="server" 
                  AssociatedControlID="HireDateUpdateTextBox" 
                  Text="Hire Date" />:</b>
              <td>
                <asp:textbox id="HireDateUpdateTextBox"
                  text='<%# Bind("HireDate", "{0:d}") %>'
                  accesskey="h" tabindex="4" runat="server" />
              </td>
            </tr>
            <tr style="height:150" valign="top">
              <td>
                <b><asp:Label runat="server" 
                  AssociatedControlID="AddressUpdateTextBox" 
                  Text="Address" />:</b>
              </td>
              <td>
                <asp:textbox id="AddressUpdateTextBox"
                  text='<%# Bind("Address") %>'
                  accesskey="a" tabindex="5" runat="server"/>
                <br/>
                <asp:textbox id="CityUpdateTextBox"
                  text='<%# Bind("City") %>'
                  accesskey="c" tabindex="6" runat="server"/> 
                <asp:textbox id="RegionUpdateTextBox"
                  text='<%# Bind("Region") %>'
                  width="40"
                  accesskey="r" tabindex="7" runat="server"/>
                <asp:textbox id="PostalCodeUpdateTextBox"
                  text='<%# Bind("PostalCode") %>'
                  width="60"
                  accesskey="p" tabindex="8" runat="server"/>
                <br/>
                <asp:textbox id="CountryUpdateTextBox"
                  text='<%# Bind("Country") %>'
                  accesskey="u" tabindex="9" runat="server"/> 
              </td>
            </tr>
            <tr>
              <td colspan="2">
                <asp:linkbutton id="UpdateButton"
                  text="Update" tabindex="10" 
                  commandname="Update"
                  runat="server"/>
                <asp:linkbutton id="CancelButton"
                  text="Cancel" tabindex="11" 
                  commandname="Cancel"
                  runat="server"/> 
              </td>
            </tr>
          </table>       
        </edititemtemplate>

      </asp:formview>

      <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="EmployeeSource"
        selectcommand="Select [EmployeeID], [LastName], [FirstName], [Title], [Address], [City], [Region], [PostalCode], [Country], [HireDate], [PhotoPath] From [Employees]"
        updatecommand="Update [Employees] Set [LastName]=@LastName, [FirstName]=@FirstName, [Title]=@Title, [Address]=@Address, [City]=@City, [Region]=@Region, [PostalCode]=@PostalCode, [Country]=@Country Where [EmployeeID]=@EmployeeID"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>

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

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

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