HtmlTextWriter.IsAttributeDefined Method
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Determines whether the specified markup attribute and its value are rendered during the next call to the RenderBeginTag method.
| IsAttributeDefined(HtmlTextWriterAttribute) |
Determines whether the specified markup attribute and its value are rendered during the next call to the RenderBeginTag method. |
| IsAttributeDefined(HtmlTextWriterAttribute, String) |
Determines whether the specified markup attribute and its value are rendered during the next call to the RenderBeginTag method. |
Determines whether the specified markup attribute and its value are rendered during the next call to the RenderBeginTag method.
protected:
bool IsAttributeDefined(System::Web::UI::HtmlTextWriterAttribute key);protected bool IsAttributeDefined(System.Web.UI.HtmlTextWriterAttribute key);member this.IsAttributeDefined : System.Web.UI.HtmlTextWriterAttribute -> boolProtected Function IsAttributeDefined (key As HtmlTextWriterAttribute) As BooleanParameters
The HtmlTextWriterAttribute associated with the markup attribute.
Returns
true if the attribute is rendered during the next call to the RenderBeginTag method; otherwise, false.
Examples
The following code example shows how to use an override of the RenderBeginTag method in a class that inherits from the HtmlTextWriter class. The RenderBeginTag override checks whether a <font> markup element will be rendered. If so, the override calls the IsAttributeDefined method to check whether the <font> element contains a Size attribute. If not, the AddAttribute method calls the GetAttributeKey method, which defines the Size attribute and sets its value to 30pt.
// If the tagKey parameter is set to a <font> element
// but a size attribute is not defined on the element,
// the AddStyleAttribute method adds a size attribute
// and sets it to 30 point.
if ( tagKey == HtmlTextWriterTag::Font )
{
if ( !IsAttributeDefined( HtmlTextWriterAttribute::Size ) )
{
AddAttribute( GetAttributeKey( "size" ), "30pt" );
}
}
// If the tagKey parameter is set to a <font> element
// but a size attribute is not defined on the element,
// the AddStyleAttribute method adds a size attribute
// and sets it to 30 point.
if (tagKey == HtmlTextWriterTag.Font)
{
if (!IsAttributeDefined(HtmlTextWriterAttribute.Size))
{
AddAttribute(GetAttributeKey("size"), "30pt");
}
}
' If the tagKey parameter is set to a <font> element
' but a size attribute is not defined on the element,
' the AddStyleAttribute method adds a size attribute
' and sets it to 30 point.
If tagKey = HtmlTextWriterTag.Font Then
If Not IsAttributeDefined(HtmlTextWriterAttribute.Size) Then
AddAttribute(GetAttributeKey("size"), "30pt")
End If
End If
Remarks
To obtain the value to be assigned to the HtmlTextWriterAttribute object, use the IsAttributeDefined(HtmlTextWriterAttribute, String) overload instead of this one.
See also
Applies to
.NET Framework 4.8.1 and other versions
| Product | Versions |
|---|---|
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
Determines whether the specified markup attribute and its value are rendered during the next call to the RenderBeginTag method.
protected:
bool IsAttributeDefined(System::Web::UI::HtmlTextWriterAttribute key, [Runtime::InteropServices::Out] System::String ^ % value);protected bool IsAttributeDefined(System.Web.UI.HtmlTextWriterAttribute key, out string value);member this.IsAttributeDefined : System.Web.UI.HtmlTextWriterAttribute * string -> boolProtected Function IsAttributeDefined (key As HtmlTextWriterAttribute, ByRef value As String) As BooleanParameters
The HtmlTextWriterAttribute associated with the markup attribute.
- value
- String
The value assigned to the attribute.
Returns
true if the attribute is rendered during the next call to the RenderBeginTag method; otherwise, false.
Remarks
If the IsAttributeDefined method returns true, the value to be assigned to the HtmlTextWriterAttribute object is returned in the value parameter.
See also
Applies to
.NET Framework 4.8.1 and other versions
| Product | Versions |
|---|---|
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
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