TagKey Property
Collapse the table of content
Expand the table of content

HtmlTextWriter.TagKey Property

 

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

Namespace:   System.Web.UI
Assembly:  System.Web (in System.Web.dll)

protected HtmlTextWriterTag TagKey { get; set; }

Property Value

Type: System.Web.UI.HtmlTextWriterTag

The markup element that is having its opening tag rendered.

Exception Condition
ArgumentOutOfRangeException

The property value cannot be set.

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

The following code example demonstrates an overridden version of the RenderBeforeContent method in a class that derives from the HtmlTextWriter class. It uses the value of the TagKey property to determine whether a server control using the custom HtmlTextWriter object is rendering a <label> markup element. If it is, a <font> element with a color attribute set to red is returned to modify the formatting of the <label> element's text.

// Override the RenderBeforeContent method to write
// a font element that applies red to the text in a Label element.
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();
    }
}

.NET Framework
Available since 1.1
Return to top
Show:
© 2016 Microsoft