Dropdown List Box 

Definition

A control with a dropdown arrow that the user clicks to display a list of options. An item in the dropdownListBox is called listBoxItem. The dropdownListBox supports client side eventing. See the EventValidationComponent description for more details.

·        design

Sets the design of the dropdownListBox.

·        enabled - inherited from EventValidationComponent.

A boolean value that defines if the dropdownListBox is click able. If the dropdownListBox is disabled (enabled = false) it is not selectable. A disabled dropdownListBox has a different color for the displayed listBoxItem.

·        id

Identification name of the dropdownListBox.

·        jsObjectNeeded - inherited from Component.

A boolean value that defines if a JavaScript object has to be generated for the dropdownListBox component.

·        labeled

Notify the component that a label has assigned to it. See the HTMLB Javadoc for more details on the LabeledComponent class.

·        model

Defines the model which provides the dropdownListBox with data. How to work with the IListModel.

·        nameOfKeyColumn

Specifies the name of the column that contains the key. This is used when you use an underlying table in the model.

·        nameOfValueColumn

Specifies the name of the column that contains the visible text. This is used when you use an underlying table in the model.

·        onClientSelect 

Defines the JavaScript fragment that is executed when the user clicks on the dropdownListbox. If both events ('onSelect' and 'onClientSelect') are specified, the 'onClientSelect' event handling method is activated first. By default the 'onSelect' event handling method is activated afterwards. In the JavaScript fragment you can cancel the activation of the 'onSelect' event handling method with the command

htmlbevent.cancelSubmit=true;

The 'onClientSelect' event is useful to pre process the form and only send the form to client if the preprocessing was successful (for example, date validation, valid number format etc.) to save client/server interaction.

 

A dropdownListbox click usually activates the client/server interaction. If an input field has to be filled out for further processing, the JavaScript fragment can check the necessary input on the client side and display a message if the necessary input is missing, without server interaction.

 

To use JavaScript the JSP has to use the page tag (see page tag).

·        onSelect

Defines the event handling method that will be processed when the user clicks on the enabled dropdownListbox. If you do not define a onClick event the dropdownListbox can be clicked but no event is generated.

·        requiresValidation

A boolean value that defines if the selected value in the dropdownListBox has to be validated before a server event is generated.

·        selection

Specifies the key of the listBoxItem which is displayed in the dropdownListBox.

·        tooltip

Defines the hint of the dropdownListBox which is displayed as the mouse cursor passes over the dropdownListBox, or as the mouse button is pressed but not released.

·        width

Defines the width of the dropdownListBox in pixel or percent.

 

Attributes	M	Values	Usage
design		STANDARD (d) SMALL	Taglib No tag available Classlib setDesign (DropdownListBoxDesign.SMALL)
enabled*		TRUE (d) FALSE	Taglib disabled="TRUE" Classlib setEnabled (false)
id	*	String (cs)	Taglib id = "listbox_te" Classlib setId ("listbox_te")
jsObjectNeeded**		TRUE (d) FALSE	Taglib jsObjectNeeded = "TRUE" Classlib setJsObjectNeeded (true)
labeled		TRUE FALSE (d)	Taglib No tag available Classlib setLabeled (true)
model		String	Taglib model = "mybean.model" Classlib setModel((IListModel) model)
nameOfKeyColumn		String	Taglib nameOfKeyColumn = "k1" Classlib setNameOfKeyColumn ("k1")
nameOfValueColumn		String	Taglib nameOfValueColumn = "v1" Classlib setNameOfValueColumn ("v1")
requiresValidation		TRUE FALSE (d)	Taglib No tag available Classlib setRequiresValidation(true)
selection		String	Taglib selection = "HD" Classlib setSelection("HD")
tooltip		String	Taglib tooltip = "select an item" Classlib setTooltip ("select an item")
width		Unit	Taglib width = "200" Classlib setWidth ("200")

* Method is inherited from the EventValidationComponent component. Therefor the attribute is different between the taglib and the classlib.

** Method is inherited from the Component component.

 

See the JavaScript API description for details how to access the component in JavaScript.

 

Events	M	Values	Usage
onClientSelect		String (cs)	Taglib onClientSelect="alert('Click')" Classlib setOnClientSelect("alert('Click')")
onSelect		String (cs)	Taglib onSelect="proc_listbox" Classlib setOnSelect ("proc_listbox")

 

To entries in the dropdownListBox are created with the listBoxItem control.

 

 

Example

using the taglib

<hbj:dropdownListBox            id="DDCitiesNearby"            tooltip="Cities surounding SAP"            selection="WD"            nameOfKeyColumn="KeyCol"            nameOfValueColumn="KeyVal"            onSelect="ProcessCity"            onClientSelect="PreprocessCity"            >               <hbj:listBoxItem key="HD" value="Heidelberg"    />               <hbj:listBoxItem key="HK" value="Hockenheim"    />               <hbj:listBoxItem key="WD" value="Walldorf"      />               <hbj:listBoxItem key="WL" value="Wiesloch"      />     </hbj:dropdownListBox>

 

using the classlib

Form form = (Form)this.getForm();     DropdownListBox ddl = new DropdownListBox("DDCitiesNearby");     ddl.setWidth("300");     ddl.addItem("HD","Heidelberg");     ddl.addItem("HK","Hockenheim");     ddl.addItem("WD","Walldorf");     ddl.addItem("WL","Wiesloch");     ddl.setOnSelect("ProcessCity");     ddl.setOnClientSelect("PreprocessCity");     ddl.setTooltip("Cities nearby");     ddl.setSelection("WD");     form.addComponent(ddl);

 

Result