ObjectDataSourceObjectEventHandler Delegato

Definizione

Rappresenta il metodo che gestirà gli eventi ObjectCreating e ObjectCreated del controllo ObjectDataSource.Represents the method that will handle the ObjectCreating and ObjectCreated events of the ObjectDataSource control.

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

Parametri

sender
Object

Origine dell'evento.The source of the event.

e
ObjectDataSourceEventArgs

Oggetto ObjectDataSourceEventArgs che contiene i dati dell'evento.An ObjectDataSourceEventArgs that contains the event data.

Ereditarietà
ObjectDataSourceObjectEventHandler

Esempi

Nell'esempio di codice riportato di seguito viene illustrato ObjectDataSource come utilizzare un controllo con un oggetto GridView business e un controllo per recuperare e visualizzare informazioni.The following code example demonstrates how to use an ObjectDataSource control with a business object and a GridView control to retrieve and display information. In questo esempio, come in molti scenari reali, potrebbe non essere possibile o appropriato utilizzare un'istanza predefinita dell'oggetto business con il ObjectDataSource controllo.In this example, as in many real-world scenarios, it might not be possible or appropriate to use a default instance of the business object with the ObjectDataSource control. In questo esempio, ObjectDataSource non è in grado di chiamare correttamente il costruttore senza parametri perché genererà un'eccezione.In this example, the ObjectDataSource cannot successfully call the parameterless constructor because it will throw an exception. In alcuni casi, il costruttore senza parametri potrebbe essere protetto e in altri potrebbe non inizializzare l'oggetto business allo stato desiderato.In some cases, the parameterless constructor might be protected, and in others it might not initialize the business object to a desired state. Qualunque sia il motivo, è possibile creare un'istanza dell'oggetto business autonomamente e impostare l' ObjectInstance istanza sulla proprietà ObjectDataSourceEventArgs dell'oggetto passato al gestore.Whatever the reason, you can instantiate the business object yourself and set the instance to the ObjectInstance property of the ObjectDataSourceEventArgs object that is passed to the handler. Si tratta dell'istanza dell'oggetto business che ObjectDataSource verrà utilizzata da per eseguire le operazioni.This is the business object instance that the ObjectDataSource will use to perform its work.

<%@ Import namespace="Samples.AspNet.CS" %>
<%@ 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">
private void NorthwindLogicCreating(object sender, ObjectDataSourceEventArgs e)
{
    // Create an instance of the business object using a non-default constructor.
    EmployeeLogic eLogic = new EmployeeLogic("Not created by the default constructor!");
    
    // Set the ObjectInstance property so that the ObjectDataSource uses the created instance.
    e.ObjectInstance = eLogic;
}

</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - C# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1">
        </asp:gridview>

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          onobjectcreating="NorthwindLogicCreating"
          typename="Samples.AspNet.CS.EmployeeLogic" >
        </asp:objectdatasource>

    </form>
  </body>
</html>
<%@ Import namespace="Samples.AspNet.VB" %>
<%@ 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">
Private Sub NorthwindLogicCreating(sender As Object, e As ObjectDataSourceEventArgs)

    ' Create an instance of the business object using a non-default constructor.
    Dim eLogic As EmployeeLogic = New EmployeeLogic("Not created by the default constructor!")
    
    ' Set the ObjectInstance property so that the ObjectDataSource uses the created instance.
    e.ObjectInstance = eLogic
    
End Sub ' NorthwindLogicCreating

</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - VB Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1">
        </asp:gridview>

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          onobjectcreating="NorthwindLogicCreating"
          typename="Samples.AspNet.VB.EmployeeLogic" >
        </asp:objectdatasource>

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

Nell'esempio di codice seguente viene illustrato l'oggetto business di base di esempio usato nell'esempio precedente.The following code example demonstrates the example basic business object used in the preceding example.

namespace Samples.AspNet.CS {

using System;
using System.Collections;
using System.Web.UI;
using System.Web.UI.WebControls;

  public class EmployeeLogic {

    public EmployeeLogic() {  
        throw new NotSupportedException("Initialize data.");
    }
    
    public EmployeeLogic(string data) {
        _data = data;
    }

    private string _data;
    
    // Returns a collection of NorthwindEmployee objects.
    public ICollection GetAllEmployees () {
      ArrayList al = new ArrayList();      
      al.Add(_data);        
      return al;
    }
    
  }

}
Imports System.Collections
Imports System.Web.UI
Imports System.Web.UI.WebControls

Namespace Samples.AspNet.VB
  Public Class EmployeeLogic
    
    
    Public Sub New() 
        Throw New NotSupportedException("Initialize data.")
    
    End Sub
    
    
    Public Sub New(ByVal data As String) 
        _data = data
    
    End Sub
    
    Private _data As String
    
    
    ' Returns a collection of NorthwindEmployee objects.
    Public Function GetAllEmployees() As ICollection 
        Dim al As New ArrayList()
        al.Add(_data)
        Return al
    
    End Function 'GetAllEmployees
  End Class
End Namespace ' Samples.AspNet.VB

Commenti

Quando si crea un delegato di ObjectDataSourceObjectEventHandler, si identifica il metodo con cui gestire l'evento.When you create an ObjectDataSourceObjectEventHandler 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 altre informazioni su come gestire gli eventi, vedere la gestione e generazione di eventi.For more information about how to handle events, 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