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HtmlTextWriter.TagKey Property

Gets or sets the HtmlTextWriterTag value for the specified HTML element.

[Visual Basic]
Protected Property TagKey As HtmlTextWriterTag
[C#]
protected HtmlTextWriterTag TagKey {get; set;}
[C++]
protected: __property HtmlTextWriterTag get_TagKey();
protected: __property void set_TagKey(HtmlTextWriterTag);
[JScript]
protected function get TagKey() : HtmlTextWriterTag;
protected function set TagKey(HtmlTextWriterTag);

Property Value

The HTML element that is having its opening tag rendered.

Exceptions

Exception Type Condition
ArgumentOutOfRangeException The property value cannot be set.

Remarks

This property is of use only to classes that inherit HtmlTextWriter. You should read or set this property only in a call to the RenderBeginTag method; this is the only time it is set to a consistent value.

Example

[Visual Basic, C#, C++] The following example shows a custom HtmlTextWriter class that overrides the RenderBeforeContent method. It uses the value of TagKey property to determine whether a server control using HtmlTextWriter object is rendering an HTML < label > element. If it is, a < font > element with a color attribute set to red is returned to modify the formatting of the label's text.

[Visual Basic] 
' Override the RenderBeforeContent method to write
' a font element that applies red to the text in a Label element.
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _ 
Protected Overrides Function RenderBeforeContent() As String
   ' Check to determine whether the element being rendered
   ' is a label element. If so, render the opening tag
   ' of the font element; otherwise, call the base method.
   If TagKey = HtmlTextWriterTag.Label Then
      Return "<font color=""red"">"
   Else
      Return MyBase.RenderBeforeContent()
   End If
End Function 'RenderBeforeContent


[C#] 
// Override the RenderBeforeContent method to write
// a font element that applies red to the text in a Label element.
[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
protected override string RenderBeforeContent()
{
   // Check to determine whether the element being rendered
   // is a label element. If so, render the opening tag
   // of the font element; otherwise, call the base method.
   if(TagKey == HtmlTextWriterTag.Label)
   {
      return "<font color=\"red\">";
   }
   else
   {
      return base.RenderBeforeContent();
   }
}

[C++] 
// Override the RenderBeforeContent method to write
// a font element that applies red to the text in a Label element.
protected:
   [System::Security::Permissions::PermissionSet(System::Security::Permissions::SecurityAction::Demand, Name="FullTrust")] 
   String* RenderBeforeContent() {
// Check to determine whether the element being rendered
// is a label element. If so, render the opening tag
// of the font element; otherwise, call the base method.
if (TagKey == HtmlTextWriterTag::Label) {
   return S"<font color=\"red\">";
} else {
   return __super::RenderBeforeContent();
}
   }

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 2000, Windows XP Professional, Windows Server 2003 family

See Also

HtmlTextWriter Class | HtmlTextWriter Members | System.Web.UI Namespace | TagName

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