The Framework Web Dynpro for ABAP allows you to create and use your own input help components. A component meant to be an input help must implement the interface IWD_VALUE_HELP (see Working with Web Dynpro Component Interfaces in the area Cross-Component Programming in this documentation). After the freely programmed value help has been attached to a context attribute, the input help is automatically available for every input field linked with this attribute.
When programming with the help of interface IWD_VALUE_HELP, beware of the following:
· The method SET_VALUE_HELP_LISTENER at the interface controller of IWD_VALUE_HELP may be called only by the Web Dynpro Framework. With the help of this method, the framework passes a callback interface to the input help component. The input help component can use this interface to tell the framework that is shall be closed, for example, if data has been selected, if 'Cancel' has been applied or if an error has occurred. In addition, this interface contains the two attributes F4_CONTEXT_ELEMENT and F4_ATTRIBUTE_INFO. They describe the context element for which the F4 help has been requested.
· The events VH_WINDOW_CLOSED and VH_WINDOW_OPENED of the component interface may only be triggered by the framework. The events indicate the points in time when the input help window is closed or opened. When implementing the component interface IWD_VALUE_HELP, these events should be copied to the component interface of the input help component to make them available in the calling component and to allow its event handlers to register onto these events.
· The component interface IWD_VALUE_HELP has the interface view WD_VALUE_HELP. The views to be displayed in the input help window must be embedded into the window WD_VALUE_HELP, which belongs to the interface view.
You attach a freely programmed input help in analogy to the attachment of an OVS input help by following these steps:
1. Creating an input help component and implementing the component interface IWD_VALUE_HELP.
2. Creating a component usage for the input help component in your application component.
3. Attaching the component usage to the context attribute. In this case, for the input help mode choose free (either when creating the attribute or later in its properties table) and specify the respective component usage.
When you work with a freely programmed input help, you can still use the function Context Change Log. Note, however, that the values selected by the user are not automatically written to the change table; you must program this explcitly (see OVS Input Help and Context Change Log).