[ExtenderControlProperty] [ClientPropertyName("rotationInterval")] [DefaultValue(3), DisplayName("RotationInterval(seconds))")] public int RotationInterval { get; set; } [ExtenderControlProperty] [ClientPropertyName("imageList")] public string ImageList { get; set; }

In 5, the ScriptComponentDescriptor class contained a series of methods that provided functionality to add properties, events, components, and element references to it so that they could be included in the $create statement that was generated for us by the ScriptManager To add these entries, we override the GetScriptDescriptors method in the ExtenderControl- or ScriptControl-based class and add entries for properties, events, components, and elements matching our class properties to the SysComponent-based classes on the client This type of work was tedious and is where attributes provide a simpler approach The Toolkit comes with a series of attributes that are applied to a property that simplify the registration of properties with the ScriptComponentDescriptor The list in Table 101 compares the attributes to their ScriptComponentDescriptor method counterparts and provides a good reference as we detail the attributes

Table 101 Attributes and ScriptComponentDescriptor Methods Comparison Attribute ExtenderControlProperty ExtenderControlEvent ElementReference ComponentReference ScriptComponentDescriptor Method AddProperty AddEvent AddElementProperty AddComponentProperty

The ExtenderControlProperty attribute shown in Listing 103 is used to decorate a property that is going to be registered with the Script ComponentDescriptor If the ClientPropertyName attribute is not used, the name of the property with its current casing is used by the Script ComponentDescriptor If the ClientPropertyName attribute is used, the name provided to the attribute is used instead

The naming structure for JavaScript is a little different from NET, which should be taken into consideration if you leave the Client PropertyName attribute blank In NET, a property for a person s rst name would be FirstName, whereas in JavaScript it would be firstName

[ExtenderControlProperty] [ClientPropertyName("rotationInterval")] public int RotationInterval { get { return rotationInterval; } set { rotationInterval = value; } }

The RequiredProperty attribute (not shown in Table 101) enables you to ensure that a particular property has a value In fact, the Toolkit goes through a validation check before continuing with the attribute-processing step to ensure that all elds that require a value actually have one If you do not add a value, you receive an error during runtime as the page containing the control is rendered To round out the remaining attributes, the ExtenderControlEvent attribute is used to decorate a property that contains the name of a function that will be handling an event The ElementReference attribute is used to decorate a property that contains the name of an HTML element that will be referenced Finally, the ComponentReference attribute is used to decorate a property that contains the name of a control that will be referenced

In 5, we were forced to add script entries by building up a strongly typed collection of ScriptReference values and return them in our GetScriptReferences override Just as in the case with the Script ComponentDescriptor, this method was tedious and error prone The Toolkit comes with three attributes that are applied at the class level that make adding script references easy (see Table 102)

Table 102 ScriptReference-Related Attributes Attribute ClientScriptResource RequiredScript ClientCSSResource Description

Creates a ScriptReference for the speci ed script Ensures referenced script is included Includes a CSS le in the control

The ClientScriptResource attribute is used to create a ScriptReference entry for the speci ed script The attribute assigns the script type to the Assembly property and path to the Name property of the ScriptReference and leaves all the other values at their defaults The one nice feature about this attribute is the ability to order the scripts so that they are loaded in a speci c order, which can help in situations where dependencies occur The RequiredScript attribute shown in Listing 104 is designed to ensure that the referenced script is included before the scripts that are included with the ClientScriptResource attribute This attribute can accept a type or a script name and is mostly used with the type overload, which provides the ability to drill down into the type and extract associated ClientScriptResource attributes applied to the type The attribute also enables you to set the order that it is loaded, which again helps in situations where dependencies occur