PostBackTrigger PostBackTrigger PostBackTrigger PostBackTrigger Class

Definition

Definiert ein Steuerelement in einem UpdatePanel-Steuerelement als Postbacksteuerelement.Defines a control inside a UpdatePanel control as a postback control.

public ref class PostBackTrigger : System::Web::UI::UpdatePanelControlTrigger
public class PostBackTrigger : System.Web.UI.UpdatePanelControlTrigger
type PostBackTrigger = class
    inherit UpdatePanelControlTrigger
Public Class PostBackTrigger
Inherits UpdatePanelControlTrigger
Vererbung

Beispiele

Im folgenden Beispiel wird gezeigt, wie ein PostBackTrigger -Steuerelement für ein UpdatePanel -Steuerelement deklarativ definiert wird.The following example shows how to declaratively define a PostBackTrigger control for an UpdatePanel control. Im Panel ermöglicht ein FileUpload -Steuerelement Benutzern das Hochladen einer Datei.In the panel, a FileUpload control enables users to upload a file. Benutzer müssen zunächst überprüfen, ob die hoch zuladende Datei vorhanden ist.Users must first check whether the file to upload exists. Das Button Steuerelement, das den Ereignishandler aufruft, um den Dateinamen zu überprüfen, bewirkt ein asynchrones Postback.The Button control that calls the event handler to check the file name causes an asynchronous postback. Das Button Steuerelement, das die Datei hochlädt, wird jedoch PostBackTriggerals registriert, da Dateien nicht asynchron hochgeladen werden können.However, the Button control that uploads the file is registered as a PostBackTrigger, because files cannot be uploaded asynchronously.

<%@ 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 string saveDir = @"Uploads\";
    
    protected void UploadButton_Click(object sender, EventArgs e)
    {
        if (FileUpload1.HasFile && FileUpload1.FileBytes.Length < 10000 &&
            !CheckForFileName())
        {
            string savePath = Request.PhysicalApplicationPath + saveDir +
                Server.HtmlEncode(FileName.Text);
            //Remove comment from the next line to upload file.
            //FileUpload1.SaveAs(savePath);
            UploadStatusLabel.Text = "The file was processed successfully.";
        }
        else
        {
            UploadStatusLabel.Text = "You did not specify a file to upload, or a file name, or the file was too large. Please try again.";
        }
    }

    protected void CheckButton_Click(object sender, EventArgs e)
    {
        if (FileName.Text.Length > 0)
        {
            string s = CheckForFileName() ? "exists already." : "does not exist.";
            UploadStatusLabel.Text = "The file name choosen " + s;
        }
        else
        {
            UploadStatusLabel.Text = "Specify a file name to check.";
        }
    }
    private Boolean CheckForFileName()
    {
        System.IO.FileInfo fi = new System.IO.FileInfo(Request.PhysicalApplicationPath + 
            saveDir + Server.HtmlEncode(FileName.Text));
            return fi.Exists;
    }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>PostBackTrigger Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <asp:ScriptManager ID="ScriptManager1" runat="server" />
    The upload button is defined as a PostBackTrigger.<br/>
    <asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" runat="server">
    <ContentTemplate>
    <fieldset>
    <legend>FileUpload in an UpdatePanel</legend>
       First, enter a file name to upload your file to: 
       <asp:TextBox ID="FileName" runat="server" />
       <asp:Button ID="CheckButton" Text="Check" runat="server" OnClick="CheckButton_Click" />
       <br />
       Then, browse and find the file to upload:
       <asp:FileUpload id="FileUpload1"                 
           runat="server">
       </asp:FileUpload>
       <br />
       <asp:Button id="UploadButton" 
           Text="Upload file"
           OnClick="UploadButton_Click"
           runat="server">
       </asp:Button>    
       <br />
       <asp:Label id="UploadStatusLabel"
           runat="server" style="color:red;">
       </asp:Label>           
    </fieldset>
    </ContentTemplate>
    <Triggers>
    <asp:PostBackTrigger ControlID="UploadButton" />
    </Triggers>
    </asp:UpdatePanel>
    </div>
    </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">

    Private saveDir As String = "Uploads\\"

    Protected Sub UploadButton_Click(ByVal sender As Object, ByVal e As EventArgs)
        
        If (FileUpload1.HasFile AndAlso FileUpload1.FileBytes.Length < 10000 AndAlso _
           Not (CheckForFileName())) Then
            Dim savePath As String = Request.PhysicalApplicationPath & saveDir & _
               Server.HtmlEncode(FileName.Text)
            'Remove comment from the next line to upload file.
            'FileUpload1.SaveAs(savePath)
            UploadStatusLabel.Text = "The file was processed successfully."
        Else
            UploadStatusLabel.Text = "You did not specify a file to upload, or a file name, or the file was too large. Please try again."
        End If
        
    End Sub

    Protected Sub CheckButton_Click(ByVal sender As Object, ByVal e As EventArgs)
        If (FileName.Text.Length > 0) Then
            Dim s As String
            If (CheckForFileName()) Then
                s = "exists already."
            Else
                s = "does not exist."
            End If
            UploadStatusLabel.Text = "The file name choosen " & s
        Else
            UploadStatusLabel.Text = "Specify a file name to check."
        End If
    End Sub

    Private Function CheckForFileName() As Boolean
        Dim fi As New System.IO.FileInfo(Request.PhysicalApplicationPath & _
           saveDir & Server.HtmlEncode(FileName.Text))
        Return fi.Exists
    End Function

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>PostBackTrigger Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <asp:ScriptManager ID="ScriptManager1" runat="server" />
    The upload button is defined as a PostBackTrigger.<br/>
    <asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" runat="server">
    <ContentTemplate>
    <fieldset>
    <legend>FileUpload in an UpdatePanel</legend>
       First, enter a file name to upload your file to: 
       <asp:TextBox ID="FileName" runat="server" />
       <asp:Button ID="CheckButton" Text="Check" runat="server" OnClick="CheckButton_Click" />
       <br />
       Then, browse and find the file to upload:
       <asp:FileUpload id="FileUpload1"                 
           runat="server">
       </asp:FileUpload>
       <br />
       <asp:Button id="UploadButton" 
           Text="Upload file"
           OnClick="UploadButton_Click"
           runat="server">
       </asp:Button>    
       <br />
       <asp:Label id="UploadStatusLabel"
           runat="server" style="color:red;">
       </asp:Label>           
    </fieldset>
    </ContentTemplate>
    <Triggers>
    <asp:PostBackTrigger ControlID="UploadButton" />
    </Triggers>
    </asp:UpdatePanel>
    </div>
    </form>
</body>
</html>

Hinweise

Verwenden Sie PostBackTrigger das-Steuerelement, um UpdatePanel Steuerelemente in einem-Steuerelement zu aktivieren, damit ein Postback statt eines asynchronen Postbacks ausgelöst wird.Use the PostBackTrigger control to enable controls inside an UpdatePanel to cause a postback instead of performing an asynchronous postback.

Verwenden Sie RegisterPostBackControl die-Methode ScriptManager des-Steuer Elements, um ein Post Back Steuerelement Programm gesteuert zu registrieren.Use the RegisterPostBackControl method of the ScriptManager control to programmatically register a postback control. Sie können dann die Update -Methode UpdatePanel des-Steuer Elements aufzurufen, wenn das-Steuerelement des-Elements ein Postback ausführtYou can then call the Update method of the UpdatePanel control when the trigger control performs a postback.

Hinweis

Programmgesteuerte hinzu PostBackTrigger fügen von Steuerelementen wird nicht unterstützt.Programmatically adding PostBackTrigger controls is not supported.

Wenn ein PostBackTrigger -Steuerelement sowohl als als auch AsyncPostBackTrigger als Steuerelement festgelegt wird, wird eine-Ausnahme ausgelöst.If a control is set as both a PostBackTrigger and AsyncPostBackTrigger control, an exception is thrown.

Konstruktoren

PostBackTrigger() PostBackTrigger() PostBackTrigger() PostBackTrigger()

Initialisiert eine neue Instanz der PostBackTrigger-Klasse.Initializes a new instance of the PostBackTrigger class.

Eigenschaften

ControlID ControlID ControlID ControlID

Ruft den Namen des Steuerelements ab, das ein PostBackTrigger-Steuerelement für ein UpdatePanel-Steuerelement darstellt, oder legt diesen fest.Gets or sets the name of the control that is an PostBackTrigger control for an UpdatePanel control.

Owner Owner Owner Owner

Ruft einen Verweis auf das UpdatePanel-Steuerelement ab, das das Ziel des UpdatePanelTrigger darstellt.Gets a reference to the UpdatePanel control that the UpdatePanelTrigger targets.

(Inherited from UpdatePanelTrigger)

Methoden

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Bestimmt, ob das angegebene Objekt mit dem aktuellen Objekt identisch ist.Determines whether the specified object is equal to the current object.

(Inherited from Object)
FindTargetControl(Boolean) FindTargetControl(Boolean) FindTargetControl(Boolean) FindTargetControl(Boolean)

Sucht nach dem in der ControlID-Eigenschaft angegebenen Steuerelement.Searches for the control specified in the ControlID property.

(Inherited from UpdatePanelControlTrigger)
GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Fungiert als Standardhashfunktion.Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

Ruft den Type der aktuellen Instanz ab.Gets the Type of the current instance.

(Inherited from Object)
HasTriggered() HasTriggered() HasTriggered() HasTriggered()

Gibt einen Wert zurück, der angibt, ob der Trigger aktiviert wurde.Returns a value that indicates whether the trigger was activated.

Initialize() Initialize() Initialize() Initialize()

Initialisiert das PostBackTrigger-Objekt.Initializes the PostBackTrigger object.

MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Erstellt eine flache Kopie des aktuellen Object.Creates a shallow copy of the current Object.

(Inherited from Object)
ToString() ToString() ToString() ToString()

Gibt eine Zeichenfolge zurück, die das aktuelle PostBackTrigger-Objekt darstellt.Returns a string that represents the current PostBackTrigger object.

Gilt für:

Siehe auch