TextBox.AutoPostBack TextBox.AutoPostBack TextBox.AutoPostBack TextBox.AutoPostBack Property

Definition

Gets or sets a value that indicates whether an automatic postback to the server occurs when the TextBox control loses focus.

public:
 virtual property bool AutoPostBack { bool get(); void set(bool value); };
[System.Web.UI.Themeable(false)]
public virtual bool AutoPostBack { get; set; }
member this.AutoPostBack : bool with get, set
Public Overridable Property AutoPostBack As Boolean

Property Value

true if an automatic postback occurs when the TextBox control loses focus; otherwise, false. The default is false.

Examples

The following example shows how to use the AutoPostBack property to automatically display the sum of the values entered in the text boxes when the TextBox control loses focus.

Important

This example has a text box that accepts user input, which is a potential security threat. By default, ASP.NET Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview.

<%@ Page Language="C#" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" > 

<head>
    <title> TextBox Example </title>
<script runat="server">

      protected void Page_Load(Object sender, EventArgs e)
      {
         int Answer;

         // Due to a timing issue with when page validation occurs, call the
         // Validate method to ensure that the values on the page are valid.
         Page.Validate();

         // Add the values in the text boxes if the page is valid.
         if(Page.IsValid)
         {
            Answer = Convert.ToInt32(Value1.Text) + Convert.ToInt32(Value2.Text);

            AnswerMessage.Text = Answer.ToString();
         }

      }

   </script>

</head>

<body>

   <form id="form1" runat="server">

      <h3> TextBox Example </h3>

      <table>

         <tr>

            <td colspan="5">

               Enter integer values into the text boxes. <br />
               The two values are automatically added <br />
               when you tab out of the text boxes. <br />

            </td>

         </tr>

         <tr>

            <td colspan="5">

               &nbsp;

            </td>

         </tr>

         <tr align="center">

            <td>

               <asp:TextBox ID="Value1"
                    Columns="2"
                    MaxLength="3"
                    AutoPostBack="True"
                    Text="1"
                    runat="server"/>

            </td>

            <td>

               + 

            </td>

            <td>

               <asp:TextBox ID="Value2"
                    Columns="2"
                    MaxLength="3"
                    AutoPostBack="True"
                    Text="1"
                    runat="server"/>

            </td>

            <td>

               =

            </td>

            <td>
               
               <asp:Label ID="AnswerMessage"
                    runat="server"/>

            </td>

         </tr>

         <tr>

            <td colspan="2">

               <asp:RequiredFieldValidator
                    ID="Value1RequiredValidator"
                    ControlToValidate="Value1"
                    ErrorMessage="Please enter a value.<br />"
                    EnableClientScript="False"
                    Display="Dynamic"
                    runat="server"/>

               <asp:RangeValidator
                    ID="Value1RangeValidator"
                    ControlToValidate="Value1"
                    Type="Integer"
                    MinimumValue="1"
                    MaximumValue="100"
                    ErrorMessage="Please enter an integer <br /> between than 1 and 100.<br />"
                    EnableClientScript="False"
                    Display="Dynamic"
                    runat="server"/>

            </td>

            <td colspan="2">

               <asp:RequiredFieldValidator
                    ID="Value2RequiredValidator"
                    ControlToValidate="Value2"
                    ErrorMessage="Please enter a value.<br />"
                    EnableClientScript="False"
                    Display="Dynamic"
                    runat="server"/>

               <asp:RangeValidator
                    ID="Value2RangeValidator"
                    ControlToValidate="Value2"
                    Type="Integer"
                    MinimumValue="1"
                    MaximumValue="100"
                    ErrorMessage="Please enter an integer <br /> between than 1 and 100.<br />"
                    EnableClientScript="False"
                    Display="Dynamic"
                    runat="server"/>

            </td>

            <td>

               &nbsp
 
            </td>

         </tr>

      </table>

   </form>

</body>
</html>
<%@ Page Language="VB" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" > 

<head>
    <title> TextBox Example </title>
<script runat="server">

      Protected Sub Page_Load(sender As Object, e As EventArgs)
    
         Dim Answer As Integer

         ' Due to a timing issue with when page validation occurs, call the
         ' Validate method to ensure that the values on the page are valid.
         Page.Validate()

         ' Add the values in the text boxes if the page is valid.
         If Page.IsValid Then
 
            Answer = Convert.ToInt32(Value1.Text) + Convert.ToInt32(Value2.Text)

            AnswerMessage.Text = Answer.ToString()

         End If

      End Sub

   </script>

</head>

<body>

   <form id="form1" runat="server">

      <h3> TextBox Example </h3>

      <table>

         <tr>

            <td colspan="5">

               Enter integer values into the text boxes. <br />
               The two values are automatically added <br />
               when you tab out of the text boxes. <br />

            </td>

         </tr>

         <tr>

            <td colspan="5">

               &nbsp;

            </td>

         </tr>

         <tr align="center">

            <td>

               <asp:TextBox ID="Value1"
                    Columns="2"
                    MaxLength="3"
                    AutoPostBack="True"
                    Text="1"
                    runat="server"/>

            </td>

            <td>

               + 

            </td>

            <td>

               <asp:TextBox ID="Value2"
                    Columns="2"
                    MaxLength="3"
                    AutoPostBack="True"
                    Text="1"
                    runat="server"/>

            </td>

            <td>

               =

            </td>

            <td>
               
               <asp:Label ID="AnswerMessage"
                    runat="server"/>

            </td>

         </tr>

         <tr>

            <td colspan="2">

               <asp:RequiredFieldValidator
                    ID="Value1RequiredValidator"
                    ControlToValidate="Value1"
                    ErrorMessage="Please enter a value.<br />"
                    EnableClientScript="False"
                    Display="Dynamic"
                    runat="server"/>

               <asp:RangeValidator
                    ID="Value1RangeValidator"
                    ControlToValidate="Value1"
                    Type="Integer"
                    MinimumValue="1"
                    MaximumValue="100"
                    ErrorMessage="Please enter an integer <br /> between than 1 and 100.<br />"
                    EnableClientScript="False"
                    Display="Dynamic"
                    runat="server"/>

            </td>

            <td colspan="2">

               <asp:RequiredFieldValidator
                    ID="Value2RequiredValidator"
                    ControlToValidate="Value2"
                    ErrorMessage="Please enter a value.<br />"
                    EnableClientScript="False"
                    Display="Dynamic"
                    runat="server"/>

               <asp:RangeValidator
                    ID="Value2RangeValidator"
                    ControlToValidate="Value2"
                    Type="Integer"
                    MinimumValue="1"
                    MaximumValue="100"
                    ErrorMessage="Please enter an integer <br /> between than 1 and 100.<br />"
                    EnableClientScript="False"
                    Display="Dynamic"
                    runat="server"/>

            </td>

            <td>

               &nbsp
 
            </td>

         </tr>

      </table>

   </form>

</body>
</html>

Remarks

Use the AutoPostBack property to specify whether an automatic postback to the server will occur when the TextBox control loses focus. Pressing the ENTER or the TAB key while in the TextBox control is the most common way to change focus.

Note

If the TextBox control's parent container contains a button marked as the default button (for example, if the container's DefaultButton or DefaultButton property is set), the default button's Click event is not raised in response to the automatic postback.

This property cannot be set by themes or style sheet themes. For more information, see ThemeableAttribute and ASP.NET Themes and Skins.

Applies to

See also