HttpCapabilitiesBase.RequiresSpecialViewStateEncoding Property

Reference

Definition

Namespace:: System.Web.Configuration

Assembly:: System.Web.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Gets a value indicating whether the browser requires VIEWSTATE values to be specially encoded.

public:
 virtual property bool RequiresSpecialViewStateEncoding { bool get(); };

public virtual bool RequiresSpecialViewStateEncoding { get; }

member this.RequiresSpecialViewStateEncoding : bool

Public Overridable ReadOnly Property RequiresSpecialViewStateEncoding As Boolean

Property Value

Boolean

true if the browser requires VIEWSTATE values to be specially encoded; otherwise, false. The default is false.

Examples

The following code example shows how to determine whether the browser requires VIEWSTATE values to be specially encoded.

<%@ 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">
    void Page_Load(Object Sender, EventArgs e)
    {
        CheckBrowserCaps();
    }

    void CheckBrowserCaps()
    {
        String labelText = "";
        System.Web.HttpBrowserCapabilities myBrowserCaps = Request.Browser;
        if (((System.Web.Configuration.HttpCapabilitiesBase)myBrowserCaps).RequiresSpecialViewStateEncoding)
        {
            labelText = "Browser requires view state values to be specially encoded.";
        }
        else
        {
            labelText = "Browser does not require view state values to be specially encoded.";
        }

        Label1.Text = labelText;
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>Browser Capabilities Sample</title>
</head>
<body>
    <form runat="server" id="form1">
        <div>
            Browser Capabilities:
            <p/><asp:Label ID="Label1" Runat="server" />
        </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">
    Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
        CheckBrowserCaps()
    End Sub

    Function CheckBrowserCaps()

        Dim labelText As String = ""
        Dim myBrowserCaps As System.Web.HttpBrowserCapabilities = Request.Browser
        If (CType(myBrowserCaps, System.Web.Configuration.HttpCapabilitiesBase)).RequiresSpecialViewStateEncoding Then
            labelText = "Browser requires view state values to be specially encoded."
        Else
            labelText = "Browser does not require view state values to be specially encoded."
        End If

        Label1.Text = labelText

    End Function 'CheckBrowserCaps
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>Browser Capabilities Sample</title>
</head>
<body>
    <form runat="server" id="form1">
        <div>
            Browser Capabilities:
            <p/><asp:Label ID="Label1" Runat="server" />
        </div>
    </form>
</body>
</html>

Remarks

HTTP is a stateless protocol, and VIEWSTATE is one mechanism used to persist client changes across multiple requests. Each control on a Web page contains a ViewState property, which represents the accumulation of any changes made by the client. In a Web Forms page, these changes are encoded in postback data as the value of an HTML <input> element with a type attribute of hidden. For example:

<input type="hidden" name="__VIEWSTATE" value="t0PH_u56?cDxleHQ7P=" />

If true, non-alphabetic characters in the VIEWSTATE value will not be sent correctly by the browser, nor by an intermediate gateway. To correct this, server-control adapters replace non-alphabetic characters in the VIEWSTATE value with ones that do not require encoding in HTTP requests.

Applies to

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