FormView.ItemUpdating Event

 

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 ItemUpdating As FormViewUpdateEventHandler

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 NIB: Consuming Events.

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


<%@ 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 EmployeeFormView_ItemUpdating(ByVal sender As Object, ByVal e As FormViewUpdateEventArgs) Handles EmployeeFormView.ItemUpdating

    ' 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.
    Dim emptyFieldList As ArrayList = ValidateFields(CType(e.NewValues, OrderedDictionary))

    If emptyFieldList.Count > 0 Then

      ' The user left some fields empty. Display an error message.

      ' Use the Keys property to retrieve the key field value.
      Dim keyValue As String = 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.
      Dim value As String
      For Each value In emptyFieldList

        ' Use the OldValues property access the original value
        ' of a field.
        MessageLabel.Text &= value & " - Original Value = " & _
          e.OldValues(value).ToString() & "<br />"

      Next

      ' Cancel the update operation.
      e.Cancel = True

    Else

      ' The field values passed validation. Clear the
      ' error message label.
      MessageLabel.Text = ""

    End If

  End Sub

  Function ValidateFields(ByVal list As OrderedDictionary) As ArrayList

    ' Create an ArrayList object to store the
    ' names of any empty fields.
    Dim emptyFieldList As New ArrayList()

    ' Iterate though the field values entered by
    ' the user and check for an empty field.
    Dim entry As DictionaryEntry
    For Each entry In list

      If entry.Value.Equals("") Then

        ' Add the field name to the ArrayList object.
        emptyFieldList.Add(entry.Key.ToString())

      End If

    Next

    Return emptyFieldList

  End Function

  Sub EmployeeFormView_ModeChanged(ByVal sender As Object, ByVal e As EventArgs) Handles EmployeeFormView.ModeChanged

    ' Clear the error message label.
    MessageLabel.Text = ""

  End Sub

</script>

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

      <h3>FormViewUpdateEventArgs Example</h3>

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

.NET Framework
Available since 2.0
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