Web Dynpro AbstractDropDownByKey API - IWDAbstractDropDownByKey 

Definition

The AbstractDropDownByKey class which implements the IWDAbstractDropDownByKey interface is the abstract base class of all dropdown list boxes that use the Key Binding Model for data binding.

The dropdown listbox offers a selection list to the user from which to choose one or no entry; it consists of a text field, a pushbutton and a selection list. An already selected list entry is displayed in the text field. When selecting the button, a list with all possible values is displayed.

The set of values that can be selected results from the value set of the data type of the attribute to which the selectedKey property is bound. The description for the value is displayed.

Data Binding

The context provides the content to be displayed within the UI element, the corresponding keys and the selected key.

The context must provide the node X that can contain 0 to n elements. (X.cardinality=0..n). The node must contain the attribute y whose data type can contain a value set (set of value/description pairs). The keys of the dropdown listbox are the values of this value set. The texts displayed in the selection list are the respective descriptions. The selected key is provided by the current value of the attribute y.

The selectedKey property of the DropDownByKey UI element is bound to the attribute y by assigning the path of the context X.y to the selectedKey property. For further information, refer to Data Binding of a Dropdown List Box and Radio Button Group. For a code example, refer to Key Binding.

Example for Data Binding of the DropDownByKey UI Element:

Procedure at design time:

       1.      Insert the DropDownByIndex UI element into the TestView (see 1).

       2.      Define in the Java Dictionary a simple data type.

       3.      Define the values and the respective descriptions (see table under 3) for this data type. Then create the context structure, as described in step 3.

       4.      Within any context structure, define a value attribute y of a simple data type, which contains the corresponding value set.

       5.      Bind the property selectedKey to the value attribute y with path <path>.y.

Behavior at runtime:

Step 5 shows the dropdown list box with the possible values Small, Medium, and Large, as it is displayed in the browser as the result of the declarative design time definitions.

Description of the UI Element Property

·        selectedKey
Use this property to determine the value from the value set, which is to be selected from the list of the dropdown listbox.

Overview of Inherited and Additional Properties

Name	Interface	Type	Initial Value	Bindable	Value Required
enabled	IWDUIElement	boolean	true	bindable	No
readOnly	AbstractDropDown	boolean	false	bindable	No
selectedKey	IWDAbstracDropDownByKey	String		bindable_mandatory	Yes
state	IWDAbstractDropDown	WDState	normal	bindable	No
tooltip	IWDUIElement	String (TranslatableText)		bindable	No
visible	IWDUIElement	WDVisibility	visible	bindable	No
width	IWDAbstractDropDown	String		bindable	No

Events

·        onSelect
This property can assign the action to be executed when the user selects a list entry from the dropdown list box.

Event Parameter	Type	Description
key	String	Key of the selected entry.

See Event Parameter and Parameter Mapping.

Subordinate Interfaces

IWDDropDownByKey.

Methods in the Web Dynpro IWDAbstractDropDownByKey API

Method Name	Parameter	Return Value	Short Description
bindingOfSelectedKey		String	Returns the path of the context element to which the selectedKey property is bound. Returns NULL if no binding exists.
bindSelectedKey	(String path)		Binds the value of the selectedKey property to the context element specified by the path.
getOnSelect		IWDAction	Returns the action that is executed when the onSelect event is triggered.
getSelectedKey		String	Returns the value of the selectedKey property.
mappingOfOnSelect		IWDParameterMapping	Returns the parameter mapping for the onSelect action.
setOnSelect	(IWDAction action)		Sets the action that is executed when the onSelect event is triggered.
setSelectedKey	(String value)	void	Sets the value of the selectedKey property.

 

Additional methods described in the following APIs are available using inheritance: IWDAbstractDropDown, IWDUIElement, IWDViewElement.

For detailed documentation of all inherited methods, see the documentation for the relevant APIs.