SqlDataSourceView.OnUpdating(SqlDataSourceCommandEventArgs) Metodo

Riferimento

Definizione

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

Assembly:: System.Web.dll

Importante

Alcune informazioni sono relative alla release non definitiva del prodotto, che potrebbe subire modifiche significative prima della release definitiva. Microsoft non riconosce alcuna garanzia, espressa o implicita, in merito alle informazioni qui fornite.

Genera l'evento Updating prima del tentativo del controllo SqlDataSource di eseguire un'operazione di aggiornamento.

protected:
 virtual void OnUpdating(System::Web::UI::WebControls::SqlDataSourceCommandEventArgs ^ e);

protected virtual void OnUpdating (System.Web.UI.WebControls.SqlDataSourceCommandEventArgs e);

abstract member OnUpdating : System.Web.UI.WebControls.SqlDataSourceCommandEventArgs -> unit
override this.OnUpdating : System.Web.UI.WebControls.SqlDataSourceCommandEventArgs -> unit

Protected Overridable Sub OnUpdating (e As SqlDataSourceCommandEventArgs)

Parametri

e: SqlDataSourceCommandEventArgs

Oggetto SqlDataSourceCommandEventArgs che contiene i dati dell'evento.

Esempio

Nell'esempio di codice seguente viene illustrato come visualizzare i dati recuperati da un database di Microsoft SQL Server in un DropDownList controllo e aggiornare il record usando un TextBox controllo. Nell'esempio viene illustrato come usare un oggetto per aggiungere il DbTransaction contesto delle transazioni quando si usa il controllo per aggiornare i SqlDataSource dati.

<%@Page  Language="C#" %>
<%@Import Namespace="System.Data" %>
<%@Import Namespace="System.Data.Common" %>
<%@Import Namespace="System.Data.SqlClient" %>
<%@Import Namespace="System.Diagnostics" %>
<!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 On_Click(Object source, EventArgs e) {    
    SqlDataSource1.Update();
 }

 private void OnSqlUpdating(Object source, SqlDataSourceCommandEventArgs e) {
    DbCommand command = e.Command;
    DbConnection cx  = command.Connection;    
    cx.Open();    
    DbTransaction tx = cx.BeginTransaction();
    command.Transaction = tx;
 }

 private void OnSqlUpdated(Object source, SqlDataSourceStatusEventArgs e) {
    DbCommand command = e.Command;
    DbTransaction tx = command.Transaction;
    
    // In this code example the OtherProcessSucceeded variable represents
    // the outcome of some other process that occurs whenever the data is 
    // updated, and must succeed for the data change to be committed. For 
    // simplicity, we set this value to true. 
    bool OtherProcessSucceeded = true;
    
    if (OtherProcessSucceeded) {
        tx.Commit();
        Label2.Text="The record was updated successfully!";
    }
    else {
        tx.Rollback();
        Label2.Text="The record was not updated.";
    }
 }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="form1" runat="server">
      <asp:SqlDataSource
          id="SqlDataSource1"
          runat="server"
          ConnectionString="<%$ ConnectionStrings:MyNorthwind%>"
          SelectCommand="SELECT EmployeeID, LastName, Address FROM Employees"
          UpdateCommand="UPDATE Employees SET Address=@Address WHERE EmployeeID=@EmployeeID"
          OnUpdating="OnSqlUpdating"
          OnUpdated ="OnSqlUpdated">
          <UpdateParameters>
              <asp:ControlParameter Name="Address" ControlId="TextBox1" PropertyName="Text"/>
              <asp:ControlParameter Name="EmployeeID" ControlId="DropDownList1" PropertyName="SelectedValue"/>
          </UpdateParameters>
      </asp:SqlDataSource>

      <asp:DropDownList
          id="DropDownList1"
          runat="server"
          DataTextField="LastName"
          DataValueField="EmployeeID"
          DataSourceID="SqlDataSource1">
      </asp:DropDownList>

      <br />
      <asp:Label id="Label1" runat="server" Text="Enter a new address for the selected user."
        AssociatedControlID="TextBox1" />
      <asp:TextBox id="TextBox1" runat="server" />
      <asp:Button id="Submit" runat="server" Text="Submit" OnClick="On_Click" />

      <br /><asp:Label id="Label2" runat="server" Text="" />

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

<%@Page  Language="VB" %>
<%@Import Namespace="System.Data" %>
<%@Import Namespace="System.Data.Common" %>
<%@Import Namespace="System.Diagnostics" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

 Sub On_Click(ByVal source As Object, ByVal e As EventArgs)
        SqlDataSource1.Update()
 End Sub 'On_Click

 Sub On_Sql_Updating(ByVal source As Object, ByVal e As SqlDataSourceCommandEventArgs)
     Dim command as DbCommand
     Dim connection as DbConnection
     Dim transaction as DbTransaction
     
     command    = e.Command
     connection = command.Connection     
     connection.Open()     
     transaction = connection.BeginTransaction()
     command.Transaction = transaction
 
 End Sub 'On_Sql_Updating
 
 Sub On_Sql_Updated(ByVal source As Object, ByVal e As SqlDataSourceStatusEventArgs)
 
    Dim command As DbCommand
    Dim transaction As DbTransaction
    
    command = e.Command
    transaction = command.Transaction
    
    ' In this code example the OtherProcessSucceeded variable represents
    ' the outcome of some other process that occurs whenever the data is 
    ' updated, and must succeed for the data change to be committed. For 
    ' simplicity, we set this value to true. 
    Dim OtherProcessSucceeded as Boolean = True
    
    If (OtherProcessSucceeded) Then
        transaction.Commit()
        Label2.Text="The record was updated successfully!"
    Else    
        transaction.Rollback()
        Label2.Text="The record was not updated."
    End If
 End Sub ' On_Sql_Updated
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="form1" runat="server">
      <asp:SqlDataSource
          id="SqlDataSource1"
          runat="server"
          ConnectionString="<%$ ConnectionStrings:MyNorthwind%>"
          SelectCommand="SELECT EmployeeID, LastName, Address FROM Employees"
          UpdateCommand="UPDATE Employees SET Address=@Address WHERE EmployeeID=@EmployeeID"
          OnUpdating="On_Sql_Updating"
          OnUpdated ="On_Sql_Updated">
          <UpdateParameters>
              <asp:ControlParameter Name="Address" ControlId="TextBox1" PropertyName="Text"/>
              <asp:ControlParameter Name="EmployeeID" ControlId="DropDownList1" PropertyName="SelectedValue"/>
          </UpdateParameters>
      </asp:SqlDataSource>

      <asp:DropDownList
          id="DropDownList1"
          runat="server"
          DataTextField="LastName"
          DataValueField="EmployeeID"
          DataSourceID="SqlDataSource1">
      </asp:DropDownList>

      <br />
      <asp:Label id="Label1" runat="server" Text="Enter a new address for the selected user."
        AssociatedControlID="TextBox1" />
      <asp:TextBox id="TextBox1" runat="server" />
      <asp:Button id="Submit" runat="server" Text="Submit" OnClick="On_Click" />

      <br /><asp:Label id="Label2" runat="server" Text="" />

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

Commenti

Quando viene generato un evento, il gestore dell'evento viene richiamato tramite un delegato. Per altre informazioni su come gestire gli eventi, vedere la gestione e generazione di eventi.

Il metodo OnUpdating consente inoltre alle classi derivate di gestire l'evento senza associare un delegato. È la tecnica consigliata per la gestione dell'evento in una classe derivata.

Note per gli eredi

Quando si esegue l'override di OnUpdating(SqlDataSourceCommandEventArgs) in una classe derivata, assicurarsi di chiamare il OnUpdating(SqlDataSourceCommandEventArgs) metodo per la classe base in modo che i delegati registrati ricevano l'evento.

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