register-a-remove-change-handler-7cd046f.md

Register a Remove Change Handler

Register a Remove change type with its change handler to a control.

In the library.js file of the control library, map the change type for the remove action to the corresponding change handler.

If the default change type and change handler of the SAPUI5 flexibility library are suitable for the remove action of your control, simply enter default as the change handler. However, if at least one change type for a control does not use the default change handler, create a <control\>.flexibility.js file and refer to it as in the RemoveGroup example in the next code sample.

Let's take a look at an example. In the case of sap.ui.comp.smartform.Group, the change type hideControl is used, along with the default handler for this change type. On the other hand, for sap.ui.comp.smartform.SmartForm, a custom change handler is used to remove a group.

Sample Code:

Snippet of library.js

sap.ui.define(['sap/ui/core/Lib'], function(Library) {
  /**
  * SAPUI5 library with smart controls.
  *
  * @namespace
  * @name sap.ui.comp
  * @public
  */
  Library.init({
    extensions: {
        flChangeHandlers: {
            "sap.ui.comp.smartform.SmartForm": {
                "removeGroup": "sap/ui/comp/smartform/flexibility/changes/RemoveGroup",
            },
            "sap.ui.comp.smartform.Group": {
                "hideControl": "default"
            }
        }
    }
  });
});

The Default SAPUI5 Flexibility Change Handler

Whenever the Remove action on a control can be performed by simply setting its visible attribute to false, we recommend to reuse the default change handler HideControl for the implementation.

Custom Change Handler Implementation

If the default HideControl change handler is not sufficient, you can implement a change handler for removing a control (see Writing a Custom Change Handler).

The change handler will get the following information as change-specific information:

Sample Code:

Change specific info for the remove action

{
    removedElement : <element being removed>
}

Usually the removedElement equals the selector, but for some composite controls where you tweaked the design-time metadata you can deviate from this.