ObjectDataSourceView.Deleting Evento

Definição

Ocorre antes de uma operação Delete.Occurs before a Delete operation.

public:
 event System::Web::UI::WebControls::ObjectDataSourceMethodEventHandler ^ Deleting;
public event System.Web.UI.WebControls.ObjectDataSourceMethodEventHandler Deleting;
member this.Deleting : System.Web.UI.WebControls.ObjectDataSourceMethodEventHandler 
Public Custom Event Deleting As ObjectDataSourceMethodEventHandler 

Tipo de evento

ObjectDataSourceMethodEventHandler

Exemplos

O exemplo de código a seguir demonstra como usar um ObjectDataSource controle com um objeto comercial e um GridView controle para excluir dados.The following code example demonstrates how to use an ObjectDataSource control with a business object and a GridView control to delete data. GridViewInicialmente, o exibe um conjunto de todos os funcionários, usando o método especificado pela SelectMethod propriedade para recuperar os dados do EmployeeLogic objeto.The GridView initially displays a set of all employees, using the method that is specified by the SelectMethod property to retrieve the data from the EmployeeLogic object. Como a AutoGenerateDeleteButton propriedade é definida como true , o GridView controle exibe automaticamente um botão de exclusão .Because the AutoGenerateDeleteButton property is set to true, the GridView control automatically displays a Delete button.

Se você clicar no botão excluir , a Delete operação será executada usando o método especificado pela DeleteMethod propriedade e quaisquer parâmetros especificados na DeleteParameters coleção.If you click the Delete button, the Delete operation is performed using the method that is specified by the DeleteMethod property and any parameters that are specified in the DeleteParameters collection. Neste exemplo de código, algumas etapas de pré-processamento e pós-processamento também são executadas.In this code example, some preprocessing and post-processing steps are also performed. O NorthwindEmployeeDeleting delegado é chamado para manipular o Deleting evento antes que a Delete operação seja executada, e o NorthwindEmployeeDeleted delegado é chamado para manipular o Deleted evento após a conclusão da Delete operação, para executar uma manipulação de exceção.The NorthwindEmployeeDeleting delegate is called to handle the Deleting event before the Delete operation is performed, and the NorthwindEmployeeDeleted delegate is called to handle the Deleted event after the Delete operation has completed, to perform an exception handling. Neste exemplo, se um NorthwindDataException for lançado, ele será tratado por este delegado.In this example, if a NorthwindDataException is thrown, it is handled by this delegate.

Para examinar a implementação do EmployeeLogic objeto comercial de camada intermediária que este exemplo de código usa, consulte ObjectDataSourceStatusEventArgs .To examine the implementation of the EmployeeLogic middle-tier business object that this code example uses, see ObjectDataSourceStatusEventArgs.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS" Assembly="Samples.AspNet.CS" %>
<%@ 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 NorthwindEmployeeDeleting(object source, ObjectDataSourceMethodEventArgs e)
{
  // The GridView passes the ID of the employee
  // to be deleted. However, the buisiness object, EmployeeLogic,
  // requires a NorthwindEmployee parameter, named "ne". Create
  // it now and add it to the parameters collection.
  IDictionary paramsFromPage = e.InputParameters;
  if (paramsFromPage["EmpID"] != null) {
    NorthwindEmployee ne
      = new NorthwindEmployee( Int32.Parse(paramsFromPage["EmpID"].ToString()));
    // Remove the old EmpID parameter.
    paramsFromPage.Clear();
    paramsFromPage.Add("ne", ne);
  }
}

private void NorthwindEmployeeDeleted(object source, ObjectDataSourceStatusEventArgs e)
{
  // Handle the Exception if it is a NorthwindDataException
  if (e.Exception != null)
  {

    // Handle the specific exception type. The ObjectDataSource wraps
    // any Exceptions in a TargetInvokationException wrapper, so
    // check the InnerException property for expected Exception types.
    if (e.Exception.InnerException is NorthwindDataException)
    {
      Label1.Text = e.Exception.InnerException.Message;
      // Because the exception is handled, there is
      // no reason to throw it.
      e.ExceptionHandled = true;
    }
  }
}

</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"
          autogeneratedeletebutton="true"
          autogeneratecolumns="false"
          datakeynames="EmpID">
          <columns>
            <asp:boundfield headertext="EmpID" datafield="EmpID" />
            <asp:boundfield headertext="First Name" datafield="FirstName" />
            <asp:boundfield headertext="Last Name" datafield="LastName" />
          </columns>
        </asp:gridview>

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          deletemethod="DeleteEmployee"
          ondeleting="NorthwindEmployeeDeleting"
          ondeleted="NorthwindEmployeeDeleted"
          typename="Samples.AspNet.CS.EmployeeLogic">
          <deleteparameters>
            <asp:parameter name="EmpID" type="Int32" />
          </deleteparameters>
        </asp:objectdatasource>

        <asp:label id="Label1" runat="server" />

    </form>
  </body>
</html>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB" Assembly="Samples.AspNet.VB" %>
<%@ 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">
' Called before a Delete operation.
    Private Sub NorthwindEmployeeDeleting(ByVal source As Object, ByVal e As ObjectDataSourceMethodEventArgs)

        ' The GridView passes the ID of the employee
        ' to be deleted. However, the business object, EmployeeLogic,
        ' requires a NorthwindEmployee parameter, named "ne". Create
        ' it now and add it to the parameters collection.
        Dim paramsFromPage As IDictionary = e.InputParameters
  
        If Not paramsFromPage("EmpID") Is Nothing Then
    
            Dim ne As New NorthwindEmployee(paramsFromPage("EmpID").ToString())
            ' Remove the old EmpID parameter.
            paramsFromPage.Clear()
            paramsFromPage.Add("ne", ne)
    
    
        End If
    End Sub ' NorthwindEmployeeDeleting

    ' Called after a Delete operation.
    Private Sub NorthwindEmployeeDeleted(ByVal source As Object, ByVal e As ObjectDataSourceStatusEventArgs)
        ' Handle the Exception if it is a NorthwindDataException.
        If Not e.Exception Is Nothing Then

            ' Handle the specific exception type. The ObjectDataSource wraps
            ' any Exceptions in a TargetInvokationException wrapper, so
            ' check the InnerException property for the expected Exception types.
            If e.Exception.InnerException.GetType().Equals(GetType(NorthwindDataException)) Then

                Label1.Text = e.Exception.InnerException.Message
                ' Because the exception is handled, there is
                ' no reason to throw it.
                e.ExceptionHandled = True
      
            End If
        End If
    End Sub ' NorthwindEmployeeDeleted
</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"
          autogeneratedeletebutton="true"
          autogeneratecolumns="false"
          datakeynames="EmpID">
          <columns>
            <asp:boundfield headertext="EmpID" datafield="EmpID" />
            <asp:boundfield headertext="First Name" datafield="FirstName" />
            <asp:boundfield headertext="Last Name" datafield="LastName" />
          </columns>
        </asp:gridview>

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          deletemethod="DeleteEmployee"
          ondeleting="NorthwindEmployeeDeleting"
          ondeleted="NorthwindEmployeeDeleted"
          typename="Samples.AspNet.VB.EmployeeLogic">
          <deleteparameters>
            <asp:parameter name="EmpID" type="Int32" />
          </deleteparameters>
        </asp:objectdatasource>

        <asp:label id="Label1" runat="server" />

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

Comentários

Manipule o Deleting evento para executar operações de inicialização adicionais que são específicas para seu aplicativo, para validar os valores dos parâmetros ou para alterar os valores de parâmetro antes que o ObjectDataSource controle execute a Delete operação.Handle the Deleting event to perform additional initialization operations that are specific to your application, to validate the values of parameters, or to change the parameter values before the ObjectDataSource control performs the Delete operation. Os parâmetros estão disponíveis como uma IDictionary coleção que é acessada pela InputParameters propriedade, que é exposta pelo ObjectDataSourceMethodEventArgs objeto.The parameters are available as an IDictionary collection that is accessed by the InputParameters property, which is exposed by the ObjectDataSourceMethodEventArgs object.

Para obter mais informações sobre como lidar com eventos, consulte manipulando e gerando eventos.For more information about how to handle events, see Handling and Raising Events.

Aplica-se a

Confira também