GridViewPageEventHandler Delegato

Definizione

Rappresenta il metodo che gestisce l'evento PageIndexChanging di un controllo GridView.Represents the method that handles the PageIndexChanging event of a GridView control.

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

Parametri

sender
Object

Origine dell'evento.The source of the event.

e
GridViewPageEventArgs

Oggetto GridViewPageEventArgs che contiene i dati dell'evento.A GridViewPageEventArgs object that contains the event data.

Ereditarietà
GridViewPageEventHandler

Esempi

Nell'esempio seguente viene illustrato come aggiungere un GridViewPageEventHandler delegato PageIndexChanging a livello di codice all'evento di GridView un controllo.The following example demonstrates how to programmatically add a GridViewPageEventHandler delegate to the PageIndexChanging event of a GridView control.


<%@ 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 control.
    GridView customersGridView = new GridView();

    // Set the GridView object's properties.
    customersGridView.ID = "CustomersGridView";
    customersGridView.DataSourceID = "CustomersSource";
    customersGridView.AutoGenerateColumns = true;
    customersGridView.EmptyDataText = "No data available.";
    customersGridView.AllowPaging = true;
    customersGridView.AutoGenerateEditButton = true;
    customersGridView.PagerSettings.Mode = PagerButtons.Numeric;
    customersGridView.PagerSettings.Position = PagerPosition.Bottom;
    customersGridView.PagerSettings.PageButtonCount = 10;
    customersGridView.PagerStyle.BackColor = System.Drawing.Color.LightBlue;
    customersGridView.DataKeyNames = new String[] { "CustomerID" };

    // Programmatically register the event-handling methods.
    customersGridView.PageIndexChanging += new GridViewPageEventHandler(this.CustomersGridView_PageIndexChanging);
    customersGridView.RowCancelingEdit += new GridViewCancelEditEventHandler(this.CustomersGridView_RowCancelingEdit);

    // Add the GridView control to the Controls collection
    // of the PlaceHolder control.
    GridViewPlaceHolder.Controls.Add(customersGridView);
    
  }          

  void CustomersGridView_PageIndexChanging(Object sender, GridViewPageEventArgs e)
  {

    // User the sender parameter to retrieve the GridView control
    // that raised the event.
    GridView customersGridView = (GridView)sender;
    
    // Cancel the paging operation if the user attempts to navigate
    // to another page while the GridView control is in edit mode. 
    if (customersGridView.EditIndex != -1)
    {
      // Use the cancel property to cancel the paging operation.
      e.Cancel = true;
      
      // Display an error message.
      int newPageNumber = e.NewPageIndex + 1;
      Message.Text = "Please update the record before moving to page " +
        newPageNumber.ToString() + ".";
    }
    else
    {
      // Clear the error message.
      Message.Text = "";
    }
    
  }

  void CustomersGridView_RowCancelingEdit(Object sender, GridViewCancelEditEventArgs e)
  {
    // Clear the error message.
    Message.Text = "";
  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewPageEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewPageEventHandler 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="CustomersSource"
        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>


<%@ 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 control.
    Dim customersGridView As New GridView()

    ' Set the GridView object's properties.
    customersGridView.ID = "CustomersGridView"
    customersGridView.DataSourceID = "CustomersSource"
    customersGridView.AutoGenerateColumns = True
    customersGridView.EmptyDataText = "No data available."
    customersGridView.AllowPaging = True
    customersGridView.AutoGenerateEditButton = True
    customersGridView.PagerSettings.Mode = PagerButtons.Numeric
    customersGridView.PagerSettings.Position = PagerPosition.Bottom
    customersGridView.PagerSettings.PageButtonCount = 10
    customersGridView.PagerStyle.BackColor = System.Drawing.Color.LightBlue
    Dim keyArray() As String = {"CustomerID"}
    customersGridView.DataKeyNames = keyArray

    ' Programmatically register the event-handling methods.
    AddHandler customersGridView.PageIndexChanging, AddressOf CustomersGridView_PageIndexChanging
    AddHandler customersGridView.RowCancelingEdit, AddressOf CustomersGridView_RowCancelingEdit

    ' Add the GridView control to the Controls collection
    ' of the PlaceHolder control.
    GridViewPlaceHolder.Controls.Add(customersGridView)
    
  End Sub

  Sub CustomersGridView_PageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs)

    ' User the sender parameter to retrieve the GridView control
    ' that raised the event.
    Dim customersGridView As GridView = CType(sender, GridView)
    
    ' Cancel the paging operation if the user attempts to navigate
    ' to another page while the GridView control is in edit mode. 
    If customersGridView.EditIndex <> -1 Then
    
      ' Use the cancel property to cancel the paging operation.
      e.Cancel = True
      
      ' Display an error message.
      Dim newPageNumber As Integer = e.NewPageIndex + 1
      Message.Text = "Please update the record before moving to page " & _
        newPageNumber.ToString() & "."
    
    Else
    
      ' Clear the error message.
      Message.Text = ""
    
    End If
    
  End Sub

  Sub CustomersGridView_RowCancelingEdit(ByVal sender As Object, ByVal e As GridViewCancelEditEventArgs)
  
    ' Clear the error message.
    Message.Text = ""
    
  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewPageEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewPageEventHandler 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="CustomersSource"
        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>

Nell'esempio seguente viene illustrato come aggiungere GridViewPageEventHandler PageIndexChanging in modo dichiarativo un delegato all'evento GridView di un controllo.The following example demonstrates how to declaratively add a GridViewPageEventHandler delegate to the PageIndexChanging event of a GridView control.


<%@ 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_PageIndexChanging(Object sender, GridViewPageEventArgs e)
  {
    
    // Cancel the paging operation if the user attempts to navigate
    // to another page while the GridView control is in edit mode. 
    if (CustomersGridView.EditIndex != -1)
    {
      // Use the Cancel property to cancel the paging operation.
      e.Cancel = true;
      
      // Display an error message.
      int newPageNumber = e.NewPageIndex + 1;
      Message.Text = "Please update the record before moving to page " +
        newPageNumber.ToString() + ".";
    }
    else
    {
      // Clear the error message.
      Message.Text = "";
    }
    
  }

  void CustomersGridView_RowCancelingEdit(Object sender, GridViewCancelEditEventArgs e)
  {
    // Clear the error message.
    Message.Text = "";
  }

</script>

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

      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSource" 
        autogeneratecolumns="true"
        emptydatatext="No data available." 
        allowpaging="true"
        autogenerateeditbutton="true"
        datakeynames="CustomerID"  
        onpageindexchanging="CustomersGridView_PageIndexChanging"
        onrowcancelingedit="CustomersGridView_RowCancelingEdit" 
        runat="server">
                
        <pagersettings mode="Numeric"
          position="Bottom"           
          pagebuttoncount="10"/>
                      
        <pagerstyle backcolor="LightBlue"/>
                
      </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="CustomersSource"
        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>


<%@ 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_PageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs)
    
    ' Cancel the paging operation if the user attempts to navigate
    ' to another page while the GridView control is in edit mode. 
    If CustomersGridView.EditIndex <> -1 Then
    
      ' Use the Cancel property to cancel the paging operation.
      e.Cancel = True
      
      ' Display an error message.
      Dim newPageNumber As Integer = e.NewPageIndex + 1
      Message.Text = "Please update the record before moving to page " & _
        newPageNumber.ToString() & "."
    
    Else
    
      ' Clear the error message.
      Message.Text = ""
    
    End If
    
  End Sub

  Sub CustomersGridView_RowCancelingEdit(ByVal sender As Object, ByVal e As GridViewCancelEditEventArgs)
  
    ' Clear the error message.
    Message.Text = ""
    
  End Sub

</script>

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

      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSource" 
        autogeneratecolumns="true"
        emptydatatext="No data available." 
        allowpaging="true"
        autogenerateeditbutton="true"
        datakeynames="CustomerID"  
        onpageindexchanging="CustomersGridView_PageIndexChanging"
        onrowcancelingedit="CustomersGridView_RowCancelingEdit" 
        runat="server">
                
        <pagersettings mode="Numeric"
          position="Bottom"           
          pagebuttoncount="10"/>
                      
        <pagerstyle backcolor="LightBlue"/>
                
      </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="CustomersSource"
        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>

Commenti

Il GridView controllo genera l' PageIndexChanging evento quando si fa clic su un pulsante del cercapersone CommandName , ovvero un pulsante con la relativa proprietà impostata su "Page", all'interno del GridView controllo, ma prima che il controllo gestisca l'operazione di paging.The GridView control raises the PageIndexChanging event when a pager button (a button with its CommandName property set to "Page") within the control is clicked, but before the GridView control handles the paging operation. Questo consente di fornire un metodo di gestione degli eventi che esegue una routine personalizzata, ad esempio l'annullamento dell'operazione di paging, ogni volta che si verifica questo evento.This allows you to provide an event-handling method that performs a custom routine, such as canceling the paging operation, whenever this event occurs.

Nota

I pulsanti di spostamento si trovano in genere nella riga del GridView cercapersone di un controllo.Pager buttons are usually located in the pager row of a GridView control.

Quando si crea un delegato GridViewPageEventHandler, si identifica il metodo che gestirà l'evento.When you create a GridViewPageEventHandler delegate, you identify the method that will handle the event. Per associare l'evento al gestore eventi in uso, aggiungere all'evento un'istanza del delegato.To associate the event with your event handler, add an instance of the delegate to the event. Il gestore eventi viene chiamato ogni volta che si verifica l'evento, a meno che non venga rimosso il delegato.The event handler is called whenever the event occurs, unless you remove the delegate. Per ulteriori informazioni sui delegati del gestore eventi, vedere gestione e generazione di eventi.For more information about event-handler delegates, see Handling and Raising Events.

Metodi di estensione

GetMethodInfo(Delegate)

Ottiene un oggetto che rappresenta il metodo rappresentato dal delegato specificato.Gets an object that represents the method represented by the specified delegate.

Si applica a

Vedi anche