GridViewCancelEditEventHandler Delegato

  • Riferimento

Definizione

Spazio dei nomi:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Rappresenta il metodo che gestisce l'evento RowCancelingEdit di un controllo GridView.

public delegate void GridViewCancelEditEventHandler(System::Object ^ sender, GridViewCancelEditEventArgs ^ e);
public delegate void GridViewCancelEditEventHandler(object sender, GridViewCancelEditEventArgs e);
type GridViewCancelEditEventHandler = delegate of obj * GridViewCancelEditEventArgs -> unit
Public Delegate Sub GridViewCancelEditEventHandler(sender As Object, e As GridViewCancelEditEventArgs)

Parametri

sender
Object

Origine dell'evento.

e
GridViewCancelEditEventArgs

Oggetto GridViewCancelEditEventArgs contenente i dati dell'evento.

Esempio

Nell'esempio seguente viene illustrato come aggiungere a livello di codice un GridViewCancelEditEventHandler delegato all'evento RowCancelingEdit di un GridView controllo.


<%@ 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 GridView object.
    GridView customerGridView = new GridView();
         
    // Set the GridView object's properties.
    customerGridView.ID = "CustomersGridView";
    customerGridView.DataSourceID = "CustomersSqlDataSource";
    customerGridView.AutoGenerateColumns = true;
    customerGridView.AutoGenerateEditButton = true;
    customerGridView.DataKeyNames = new String[] { "CustomerID" };
        
    // Programmatically register the event-handling methods.
    customerGridView.RowCancelingEdit += new GridViewCancelEditEventHandler(this.CustomersGridView_RowCancelingEdit);
    customerGridView.RowUpdated += new GridViewUpdatedEventHandler(this.CustomersGridView_RowUpdated);
        
    // Add the GridView object to the Controls collection
    // of the PlaceHolder control.
    GridViewPlaceHolder.Controls.Add(customerGridView);
        
  }

  void CustomersGridView_RowCancelingEdit(Object sender, GridViewCancelEditEventArgs e)
  {
    
    // Display a message indicating that the update operation was canceled.
    Message.Text = "Update for row " + e.RowIndex.ToString() + " canceled."; 
    
  }

  void CustomersGridView_RowUpdated(Object sender, GridViewUpdatedEventArgs e)
  {

    // The update operation was successful. Clear the message label.
    Message.Text = "";

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewCancelEditEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewCancelEditEventHandler Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"
        runat="server"/>
                
      <br/>
            
      <asp:placeholder id="GridViewPlaceHolder"
        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="CustomersSqlDataSource"  
        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">
      </asp:sqldatasource>
            
    </form>
  </body>
</html>


<%@ 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 GridView object.
    Dim customerGridView As New GridView()
         
    ' Set the GridView object's properties.
    customerGridView.ID = "CustomersGridView"
    customerGridView.DataSourceID = "CustomersSqlDataSource"
    customerGridView.AutoGenerateColumns = True
    customerGridView.AutoGenerateEditButton = True
    customerGridView.DataKeyNames = New [String]() {"CustomerID"}
        
    ' Programmatically register the event-handling methods.
    AddHandler customerGridView.RowCancelingEdit, AddressOf CustomersGridView_RowCancelingEdit
    AddHandler customerGridView.RowUpdated, AddressOf CustomersGridView_RowUpdated
        
    ' Add the GridView object to the Controls collection
    ' of the PlaceHolder control.
    GridViewPlaceHolder.Controls.Add(customerGridView)
        
  End Sub
    
  Sub CustomersGridView_RowCancelingEdit(ByVal sender As Object, ByVal e As GridViewCancelEditEventArgs)
    
    ' Display a message indicating that the update operation was canceled.
    Message.Text = "Update for row " + e.RowIndex.ToString() + " canceled."
    
  End Sub
    
  Sub CustomersGridView_RowUpdated(ByVal sender As Object, ByVal e As GridViewUpdatedEventArgs)

    ' The update operation was successful. Clear the message label.
    Message.Text = ""

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewCancelEditEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewCancelEditEventHandler Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"
        runat="server"/>
                
      <br/>
            
      <asp:placeholder id="GridViewPlaceHolder"
        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="CustomersSqlDataSource"  
        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">
      </asp:sqldatasource>
            
    </form>
  </body>
</html>

Nell'esempio seguente viene illustrato come aggiungere in modo dichiarativo un GridViewCancelEditEventHandler delegato all'evento RowCancelingEdit di un GridView controllo.


<%@ 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 CustomersGridView_RowCancelingEdit(Object sender, GridViewCancelEditEventArgs e)
  {
    
    // Retrieve the row that raised the event from the Rows
    // collection of the GridView control.
    GridViewRow row = CustomersGridView.Rows[e.RowIndex];
    
    // The update operation was canceled. Display the 
    // primary key of the row. In this example, the primary
    // key is displayed in the second column of the GridView
    // control. To access the text of the column, use the Cells
    // collection of the row.
    Message.Text = "Update for item " + row.Cells[1].Text + " Canceled."; 
    
  }

  void CustomersGridView_RowEditing(Object sender, GridViewEditEventArgs e)
  {

    // The GridView control is entering edit mode. Clear the message label.
    Message.Text = "";

  }
  
  void CustomersGridView_RowUpdated(Object sender, GridViewUpdatedEventArgs e)
  {

    // The update operation was successful. Clear the message label.
    Message.Text = "";

  }
    
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridView RowCancelingEdit Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridView RowCancelingEdit Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"
        runat="server"/>
                
      <br/>
      
      <!-- The GridView control automatically sets the columns     -->
      <!-- specified in the datakeynames attribute as read-only.   -->
      <!-- No input controls are rendered for these columns in     -->
      <!-- edit mode.                                              -->
      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSqlDataSource" 
        autogeneratecolumns="true"
        autogenerateeditbutton="true"
        allowpaging="true" 
        datakeynames="CustomerID"
        onrowcancelingedit="CustomersGridView_RowCancelingEdit"
        onrowediting="CustomersGridView_RowEditing" 
        onrowupdated="CustomersGridView_RowUpdated"    
        runat="server">
      </asp:gridview>
            
      <!-- 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="CustomersSqlDataSource"  
        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">
      </asp:sqldatasource>
            
    </form>
  </body>
</html>


<%@ 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 CustomersGridView_RowCancelingEdit(ByVal sender As Object, ByVal e As GridViewCancelEditEventArgs)
    
    ' Retrieve the row that raised the event from the Rows
    ' collection of the GridView control.
    Dim row As GridViewRow = CustomersGridView.Rows(e.RowIndex)
    
    ' The update operation was canceled. Display the 
    ' primary key of the row. In this example, the primary
    ' key is displayed in the second column of the GridView
    ' control. To access the text of the column, use the Cells
    ' collection of the row.
    Message.Text = "Update for item " & row.Cells(1).Text & " Canceled."
    
  End Sub

  Sub CustomersGridView_RowEditing(ByVal sender As Object, ByVal e As GridViewEditEventArgs)

    ' The GridView control is entering edit mode. Clear the message label.
    Message.Text = ""

  End Sub
  
  Sub CustomersGridView_RowUpdated(ByVal sender As Object, ByVal e As GridViewUpdatedEventArgs)
    
    ' The update operation was successful. Clear the message label.
    Message.Text = ""

  End Sub
    
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridView RowCancelingEdit Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridView RowCancelingEdit Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"
        runat="server"/>
                
      <br/>
      
      <!-- The GridView control automatically sets the columns     -->
      <!-- specified in the datakeynames attribute as read-only.   -->
      <!-- No input controls are rendered for these columns in     -->
      <!-- edit mode.                                              -->
      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSqlDataSource" 
        autogeneratecolumns="true"
        autogenerateeditbutton="true"
        allowpaging="true" 
        datakeynames="CustomerID"
        onrowcancelingedit="CustomersGridView_RowCancelingEdit"
        onrowediting="CustomersGridView_RowEditing" 
        onrowupdated="CustomersGridView_RowUpdated"    
        runat="server">
      </asp:gridview>
            
      <!-- 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="CustomersSqlDataSource"  
        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">
      </asp:sqldatasource>
            
    </form>
  </body>
</html>

Commenti

L'evento RowCancelingEdit viene generato quando viene fatto clic sul pulsante Annulla di una riga in modalità di modifica, ma prima che la riga esca dalla modalità di modifica. In questo modo è possibile fornire un metodo di gestione eventi che esegue una routine personalizzata, ad esempio l'arresto dell'operazione di annullamento se la riga verrà inserita in uno stato non desiderato, ogni volta che si verifica questo evento.

Quando si crea un delegato GridViewCancelEditEventHandler, si identifica il metodo che gestirà l'evento. Per associare l'evento al gestore eventi in uso, aggiungere all'evento un'istanza del delegato. Il gestore eventi viene chiamato ogni volta che si verifica l'evento, a meno che non venga rimosso il delegato. Per altre informazioni sui delegati del gestore eventi, vedere Gestione e generazione di eventi.

Metodi di estensione

GetMethodInfo(Delegate)

Ottiene un oggetto che rappresenta il metodo rappresentato dal delegato specificato.

Si applica a

Vedi anche