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FormView.ItemUpdating Event

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

Occurs when an Update button within a FormView control is clicked, but before the update operation.

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

public event FormViewUpdateEventHandler ItemUpdating
/** @event */
public void add_ItemUpdating (FormViewUpdateEventHandler value)

/** @event */
public void remove_ItemUpdating (FormViewUpdateEventHandler value)

JScript supports the use of events, but not the declaration of new ones.

The FormView control raises the ItemUpdating event when an Update button (a button with its CommandName property set to "Update") within the control is clicked, but before the FormView control updates the record. This allows you to provide an event-handling method that performs a custom routine, such as HTML encoding the values of a record before updating it in the data source, whenever this event occurs.

A FormViewUpdateEventArgs object is passed to the event-handling method, which allows you to determine the value of an optional command argument sent to the FormView control and to indicate that the update operation should be canceled. The command argument value corresponds to the CommandArgument property of the Update button. When the CommandArgument property of the Update button is set, use the CommandArgument property to determine the value of the command argument. To cancel the update operation, set the Cancel property to true. You can also read or modify the new values entered by the user by using the Keys and NewValues properties. The Keys property contains the key fields, while the NewValues property contains the non-key fields. If you need to access the original non-key field values, use the OldValues property.

For more information about handling events, see Consuming Events.

The following example demonstrates how to use the ItemUpdating event to cancel an update operation.


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

<script runat="server">

  void EmployeeFormView_ItemUpdating(Object sender, FormViewUpdateEventArgs e)
  {

    // Validate the field values entered by the user. This
    // example determines whether the user left any fields
    // empty. The names of the empty fields are added to
    // an ArrayList object.
     
    // Use the NewValues property to access the new 
    // values entered by the user.
    ArrayList emptyFieldList = ValidateFields((OrderedDictionary)e.NewValues);

    if (emptyFieldList.Count > 0)
    {

      // The user left some fields empty. Display an error message.
      
      // Use the Keys property to retrieve the key field value.
      String keyValue = e.Keys["EmployeeID"].ToString();

      MessageLabel.Text = "You must enter a value for each field of record " +
        keyValue + ".<br/>The following fields are missing:<br/><br/>";

      // Display the missing fields.
      foreach (String value in emptyFieldList)
      {
        // Use the OldValues property to access the original value
        // of a field.
        MessageLabel.Text += value + " - Original Value = " + 
          e.OldValues[value].ToString() + "<br>";
      }

      // Cancel the update operation.
      e.Cancel = true;

    }
    else
    {
      // The field values passed validation. Clear the
      // error message label.
      MessageLabel.Text = "";
    }

  }

  ArrayList ValidateFields(OrderedDictionary list)
  {
    
    // Create an ArrayList object to store the
    // names of any empty fields.
    ArrayList emptyFieldList = new ArrayList();

    // Iterate though the field values entered by
    // the user and check for an empty field.
    foreach (DictionaryEntry entry in list)
    {
      if (entry.Value.Equals(""))
      {
        // Add the field name to the ArrayList object.
        emptyFieldList.Add(entry.Key.ToString());
      }
    }

    return emptyFieldList;
  }

  void EmployeeFormView_ModeChanged(Object sender, EventArgs e)
  {
      // Clear the error message label.
      MessageLabel.Text = "";
  }

</script>

<html>
  <body>
    <form runat="server">
        
      <h3>FormViewUpdateEventArgs Example</h3>
                       
      <asp:formview id="EmployeeFormView"
        datasourceid="EmployeeSource"
        allowpaging="true"
        datakeynames="EmployeeID"
        emptydatatext="No employees found."
        onitemupdating="EmployeeFormView_ItemUpdating"
        onmodechanged="EmployeeFormView_ModeChanged"   
        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 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>Name:</b>
              </td>
              <td>
                <asp:textbox id="FirstNameUpdateTextBox"
                  text='<%# Bind("FirstName") %>'
                  runat="server"/>
                <asp:textbox id="LastNameUpdateTextBox"
                  text='<%# Bind("LastName") %>'
                  runat="server"/>
              </td>
            </tr>
            <tr>
              <td>
                <b>Title:</b>
              </td>
              <td>
                <asp:textbox id="TitleUpdateTextBox"
                  text='<%# Bind("Title") %>'
                  runat="server"/> 
              </td>
            </tr>
            <tr height="150" valign="top">
              <td>
                <b>Address:</b>
              </td>
              <td>
                <asp:textbox id="AddressUpdateTextBox"
                  text='<%# Bind("Address") %>'
                  runat="server"/>
                <br/>
                <asp:textbox id="CityUpdateTextBox"
                  text='<%# Bind("City") %>'
                  runat="server"/> 
                <asp:textbox id="RegionUpdateTextBox"
                  text='<%# Bind("Region") %>'
                  width="40"
                  runat="server"/>
                <asp:textbox id="PostalCodeUpdateTextBox"
                  text='<%# Bind("PostalCode") %>'
                  width="60"
                  runat="server"/>
                <br/>
                <asp:textbox id="CountryUpdateTextBox"
                  text='<%# Bind("Country") %>'
                  runat="server"/> 
              </td>
            </tr>
            <tr>
              <td colspan="2">
                <asp:linkbutton id="UpdateButton"
                  text="Update"
                  commandname="Update"
                  runat="server"/>
                <asp:linkbutton id="CancelButton"
                  text="Cancel"
                  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 98, Windows 2000 SP4, 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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