HtmlTextWriter.FilterAttributes Method
Definition
Important
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Removes all the markup and style attributes on all properties of the page or Web server control.
protected:
virtual void FilterAttributes();protected virtual void FilterAttributes ();abstract member FilterAttributes : unit -> unit
override this.FilterAttributes : unit -> unitProtected Overridable Sub FilterAttributes ()Examples
The following code example shows how to use a custom class, derived from the HtmlTextWriter class, that overrides the FilterAttributes method. When called, the FilterAttributes override checks whether the text writer renders any <label> or <a> elements:
If a
<label>element is being rendered, the FilterAttributes method checks whether astyleattribute is rendered on the element and, if not, creates astyleattribute and sets it tocolor: blue.If an
<a>element is being rendered, the FilterAttributes method determines whether anhrefattribute is included and, if not, adds anhrefto the URL http://www.cohowinery.com.
// Override the FilterAttributes method to check whether
// <label> and <anchor> elements contain specific attributes.
virtual void FilterAttributes() override
{
// If the <label> element is rendered and a style
// attribute is not defined, add a style attribute
// and set its value to blue.
if ( TagKey == HtmlTextWriterTag::Label )
{
if ( !IsAttributeDefined( HtmlTextWriterAttribute::Style ) )
{
AddAttribute( "style", EncodeAttributeValue( "color:blue", true ) );
Write( NewLine );
Indent = 3;
OutputTabs();
}
}
// If an <anchor> element is rendered and an href
// attribute has not been defined, call the AddAttribute
// method to add an href attribute
// and set it to http://www.cohowinery.com.
// Use the EncodeUrl method to convert any spaces to %20.
if ( TagKey == HtmlTextWriterTag::A )
{
if ( !IsAttributeDefined( HtmlTextWriterAttribute::Href ) )
{
AddAttribute( "href", EncodeUrl( "http://www.cohowinery.com" ) );
}
}
// Call the FilterAttributes method of the base class.
__super::FilterAttributes();
}
// Override the FilterAttributes method to check whether
// <label> and <anchor> elements contain specific attributes.
protected override void FilterAttributes()
{
// If the <label> element is rendered and a style
// attribute is not defined, add a style attribute
// and set its value to blue.
if (TagKey == HtmlTextWriterTag.Label)
{
if (!IsAttributeDefined(HtmlTextWriterAttribute.Style))
{
AddAttribute("style", EncodeAttributeValue("color:blue", true));
Write(NewLine);
Indent = 3;
OutputTabs();
}
}
// If an <anchor> element is rendered and an href
// attribute has not been defined, call the AddAttribute
// method to add an href attribute
// and set it to http://www.cohowinery.com.
// Use the EncodeUrl method to convert any spaces to %20.
if (TagKey == HtmlTextWriterTag.A)
{
if (!IsAttributeDefined(HtmlTextWriterAttribute.Href))
{
AddAttribute("href", EncodeUrl("http://www.cohowinery.com"));
}
}
// Call the FilterAttributes method of the base class.
base.FilterAttributes();
}
' Override the FilterAttributes method to check whether
' <label> and <anchor> elements contain specific attributes.
Protected Overrides Sub FilterAttributes()
' If the <label> element is rendered and a style
' attribute is not defined, add a style attribute
' and set its value to blue.
If TagKey = HtmlTextWriterTag.Label Then
If Not IsAttributeDefined(HtmlTextWriterAttribute.Style) Then
AddAttribute("style", EncodeAttributeValue("color:blue", True))
Write(NewLine)
Indent = 3
OutputTabs()
End If
End If
' If an <anchor> element is rendered and an href
' attribute has not been defined, call the AddAttribute
' method to add an href attribute
' and set it to http://www.cohowinery.com.
' Use the EncodeUrl method to convert any spaces to %20.
If TagKey = HtmlTextWriterTag.A Then
If Not IsAttributeDefined(HtmlTextWriterAttribute.Href) Then
AddAttribute("href", EncodeUrl("http://www.cohowinery.com"))
End If
End If
' Call the FilterAttributes method of the base class.
MyBase.FilterAttributes()
End Sub
Remarks
Before attributes are rendered on a markup element, the FilterAttributes method is called. In turn, the FilterAttributes method calls the OnAttributeRender and OnStyleAttributeRender methods for each attribute and style to render.
