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GridViewSelectEventHandler délégué

 

Date de publication : novembre 2016

Représente la méthode qui gère les SelectedIndexChanging événements d’un GridView contrôle.

Espace de noms:   System.Web.UI.WebControls
Assembly:  System.Web (dans System.Web.dll)

public delegate void GridViewSelectEventHandler(
	object sender,
	GridViewSelectEventArgs e
)

Paramètres

sender
Type: System.Object

Source de l'événement.

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

Objet GridViewSelectEventArgs qui contient les données d'événement.

Le SelectedIndexChanging événement est déclenché lorsqu’un bouton de sélection (un bouton avec son CommandName propriété la valeur « Select ») est activé, mais avant que le GridView contrôle gère l’opération de sélection. Cela vous permet de fournir une méthode de gestion d’événements qui exécute une routine personnalisée, par exemple l’annulation de l’opération de sélection, chaque fois que cet événement se produit.

Lorsque vous créez un délégué GridViewSelectEventHandler, vous identifiez la méthode qui gérera l'événement. Pour associer l'événement au gestionnaire d'événements, ajoutez une instance du délégué à l'événement. Le gestionnaire d'événements est appelé chaque fois qu'un événement se produit, sauf si vous supprimez le délégué. Pour plus d'informations sur les délégués de gestionnaires d'événements, consultez la page NIB : événements et délégués.

L’exemple suivant montre comment ajouter par programme un GridViewSelectEventHandler déléguer à la SelectedIndexChanging événements d’un GridView contrôle.


<%@ 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 authorGridView = new GridView();

        // Set the GridView object's properties.
        authorGridView.ID = "AuthorGridView";
        authorGridView.DataSourceID = "AuthorsSqlDataSource"; 
        authorGridView.AutoGenerateColumns = true;
        authorGridView.AutoGenerateSelectButton = true;
        authorGridView.AllowPaging = true; 
        authorGridView.SelectedIndex = 1;
        authorGridView.SelectedRowStyle.BackColor = System.Drawing.Color.LightCyan;
        authorGridView.SelectedRowStyle.ForeColor = System.Drawing.Color.DarkBlue;
        authorGridView.SelectedRowStyle.Font.Bold = true;

        // Programmatically register the event-handling methods.
        authorGridView.SelectedIndexChanged += new EventHandler(this.AuthorsGridView_SelectedIndexChanged);
        authorGridView.SelectedIndexChanging += new GridViewSelectEventHandler(this.AuthorsGridView_SelectedIndexChanging);

        // Add the GridView object to the Controls collection
        // of the PlaceHolder control.
        GridViewPlaceHolder.Controls.Add(authorGridView);

    }

    void AuthorsGridView_SelectedIndexChanged(Object sender, EventArgs e)
    {

        // Get the currently selected row using the SelectedRow property.
        GridView AuthorsGridView = (GridView)sender;
        GridViewRow row = AuthorsGridView.SelectedRow;

        // Display the author's name from the selected row.
        // In this example, the second and third columns contain
        // the author's last and first name, respectively.
        Message.Text = "You selected " + row.Cells[2].Text +
            " " + row.Cells[1].Text + ".";

    }

    void AuthorsGridView_SelectedIndexChanging(Object sender, GridViewSelectEventArgs e)
    {

        // Get the currently selected row. Because the SelectedIndexChanging event
        // occurs before the select operation in the GridView control, the
        // SelectedRow property cannot be used. Instead, use the Rows collection
        // and the NewSelectedIndex property of the e argument passed to this 
        // event handler.
        GridView AuthorsGridView = (GridView)sender;
        GridViewRow row = AuthorsGridView.Rows[e.NewSelectedIndex];

        // If the user selects an author with the last name White,
        // cancel the selection operation and display an error message.
        if(row.Cells[1].Text == "White")
        {

            e.Cancel = true;
            Message.Text = "You cannot select " + row.Cells[2].Text +
            " " + row.Cells[1].Text + ".";

        }

    }

</script>

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

            <h3>GridViewSelectEventHandler Example</h3>

            <asp:placeholder id="GridViewPlaceHolder"
                runat="Server"/>

            <!-- This example uses Microsoft SQL Server and connects -->
            <!-- to the Pubs sample database.                         -->
            <asp:sqldatasource id="AuthorsSqlDataSource"  
                selectcommand="SELECT [au_lname], [au_fname], [address], [city], [state], [zip], [contract] FROM [authors]"
                connectionstring="server=localhost;database=pubs;integrated security=SSPI"
                runat="server">
            </asp:sqldatasource>

            <br/>

            <asp:label id="Message"
                runat="server"/>

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

L’exemple suivant montre comment ajouter de façon déclarative un GridViewSelectEventHandler déléguer à la SelectedIndexChanging événements d’un GridView contrôle.


<%@ 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_SelectedIndexChanged(Object sender, EventArgs e)
  {
    // Get the currently selected row using the SelectedRow property.
    GridViewRow row = CustomersGridView.SelectedRow;

    // Display the first name from the selected row.
    // In this example, the third column (index 2) contains
    // the first name.
    MessageLabel.Text = "You selected " + row.Cells[2].Text + ".";
  }

  void CustomersGridView_SelectedIndexChanging(Object sender, GridViewSelectEventArgs e)
  {
    // Get the currently selected row. Because the SelectedIndexChanging event
    // occurs before the select operation in the GridView control, the
    // SelectedRow property cannot be used. Instead, use the Rows collection
    // and the NewSelectedIndex property of the e argument passed to this 
    // event handler.
    GridViewRow row = CustomersGridView.Rows[e.NewSelectedIndex];

    // You can cancel the select operation by using the Cancel
    // property. For this example, if the user selects a customer with 
    // the ID "ANATR", the select operation is canceled and an error message
    // is displayed.
    if (row.Cells[1].Text == "ANATR")
    {
      e.Cancel = true;
      MessageLabel.Text = "You cannot select " + row.Cells[2].Text + "."; 
    }
  }

</script>

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

     <h3>GridView Select Example</h3>

     <asp:gridview id="CustomersGridView" 
       datasourceid="CustomersSource" 
       autogeneratecolumns="False"
       autogenerateselectbutton="True"
       selectedindex="1"
       onselectedindexchanged="CustomersGridView_SelectedIndexChanged"
       onselectedindexchanging="CustomersGridView_SelectedIndexChanging"   
       runat="server" DataKeyNames="CustomerID">

         <Columns>
             <asp:BoundField DataField="CustomerID" 
                 HeaderText="CustomerID" 
                 InsertVisible="False" ReadOnly="True" 
                 SortExpression="CustomerID" />
             <asp:BoundField DataField="FirstName" 
                 HeaderText="FirstName" 
                 SortExpression="FirstName" />
             <asp:BoundField DataField="MiddleName" 
                 HeaderText="MiddleName" 
                 SortExpression="MiddleName" />
             <asp:BoundField DataField="LastName" 
                 HeaderText="LastName" 
                 SortExpression="LastName" />
             <asp:BoundField DataField="Phone" 
                 HeaderText="Phone" 
                 SortExpression="Phone" />
         </Columns>

       <selectedrowstyle backcolor="LightCyan"
         forecolor="DarkBlue"
         font-bold="true"/>  

     </asp:gridview>

      <br/>

      <asp:label id="MessageLabel"
        forecolor="Red"
        runat="server"/>

      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the 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, FirstName, MiddleName, LastName, Phone FROM SalesLT.Customer"
        connectionstring="<%$ ConnectionStrings:AdventureWorksLTConnectionString %>" 
        runat="server"/>

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

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