Backend

UI5 control properties can both display data and fire events. To run backend logic when an event fires, use the client->_event method.

Basic

As an example, we use the press property of a button. To fire events to the backend, assign the result of client->_event( `MY_EVENT_NAME` ) to the matching UI5 control property. The backend can then read the event details with client->get( )-event.

METHOD z2ui5_if_app~main.

    IF client->check_on_navigated( ).

      DATA(view) = z2ui5_cl_ui5_view_builder=>factory(
          )->ele( n = `View` ns = `mvc`
              )->a( n = `xmlns`     v = `sap.m`
              )->a( n = `xmlns:mvc` v = `sap.ui.core.mvc`

              )->ele( `Page`
                  )->tag( `Button`
                      )->a( n = `text`  v = `post`
                      )->a( n = `press` v = client->_event( `BUTTON_POST` ) ).

      client->view_display( view->stringify( ) ).

    ELSEIF client->check_on_event( `BUTTON_POST` ).
      client->message_box_display( `The button was pressed` ).

    ENDIF.

ENDMETHOD.

If the backend needs more details about the event, use the arg parameter to add extra info. Three prefixes are available:

• $source — the UI5 control that fired the event (e.g., ${$source>/text} returns the button text)
• $parameters — the event parameters defined by the UI5 control (e.g., ${$parameters>/id} returns the element ID)
• $event — the UI5 event object itself (e.g., $event>sId returns the event type like press). Note: unlike the other two prefixes, $event is written without the ${...} wrapper and without a leading / — see the Event section below.

arg carries one value, which is what most events need. For two or more, use t_arg instead and pass them as a table — t_arg = VALUE #( ( `${$source>/text}` ) ( `${$parameters>/id}` ) ) — and read them back in the same order with client->get_event_arg( 2 ), ( 3 ) and so on. The two are the same wire: arg = x is exactly t_arg = VALUE #( ( x ) ).

For details, see the UI5 docs on event handler arguments and sample Z2UI5_CL_SMP_APP_167.

Source

Send properties of the event source control to the backend. The syntax ${$source>/text} reads the text property of the UI5 control that fired the event — here, the button itself, returning the button's label (post):

METHOD z2ui5_if_app~main.

    IF client->check_on_navigated( ).

      DATA(view) = z2ui5_cl_ui5_view_builder=>factory(
          )->ele( n = `View` ns = `mvc`
              )->a( n = `xmlns`     v = `sap.m`
              )->a( n = `xmlns:mvc` v = `sap.ui.core.mvc`

              )->ele( `Page`
                  )->tag( `Button`
                      )->a( n = `text`  v = `post`
                      )->a( n = `press` v = client->_event(
                                            val = `BUTTON_POST`
                                            " reads the button text → result: "post"
                                            arg = `${$source>/text}` ) ).

      client->view_display( view->stringify( ) ).

    ELSEIF client->check_on_event( `BUTTON_POST` ).
      client->message_box_display( |The button text is { client->get_event_arg( ) }| ).

    ENDIF.

ENDMETHOD.

Parameters

Read parameters of the event. The syntax ${$parameters>/id} reads the id parameter out of the event's parameter map — UI5 builds a qualified ID like mainView--button_id:

METHOD z2ui5_if_app~main.

    IF client->check_on_navigated( ).

      DATA(view) = z2ui5_cl_ui5_view_builder=>factory(
          )->ele( n = `View` ns = `mvc`
              )->a( n = `xmlns`     v = `sap.m`
              )->a( n = `xmlns:mvc` v = `sap.ui.core.mvc`

              )->ele( `Page`
                  )->tag( `Button`
                      )->a( n = `id`    v = `button_id`
                      )->a( n = `text`  v = `post`
                      )->a( n = `press` v = client->_event(
                                            val = `BUTTON_POST`
                                            " reads the event parameter 'id' → result: "mainView--button_id"
                                            arg = `${$parameters>/id}` ) ).

      client->view_display( view->stringify( ) ).

    ELSEIF client->check_on_event( `BUTTON_POST` ).
      client->message_box_display( |The button id is { client->get_event_arg( ) }| ).

    ENDIF.

ENDMETHOD.

Event

Read specific properties of the event object. The syntax $event>sId reads the sId attribute of the UI5 event — here it returns the event type name (press). Note: there's no ${...} wrapper because $event directly references the event object:

METHOD z2ui5_if_app~main.

    IF client->check_on_navigated( ).

      DATA(view) = z2ui5_cl_ui5_view_builder=>factory(
          )->ele( n = `View` ns = `mvc`
              )->a( n = `xmlns`     v = `sap.m`
              )->a( n = `xmlns:mvc` v = `sap.ui.core.mvc`

              )->ele( `Page`
                  )->tag( `Button`
                      )->a( n = `text`  v = `post`
                      )->a( n = `press` v = client->_event(
                                            val = `BUTTON_POST`
                                            " reads an event-object attribute → result: "press"
                                            arg = `$event>sId` ) ).

      client->view_display( view->stringify( ) ).

    ELSEIF client->check_on_event( `BUTTON_POST` ).
      client->message_box_display( |The event id is { client->get_event_arg( ) }| ).

    ENDIF.

ENDMETHOD.

WARNING

You can read any object attribute, but use only public and released attributes to avoid compatibility issues with future UI5 versions.

More Than One Argument

get_event_arg( ) without a value reads the first argument, which is the only one a wire written with arg = carries. A wire written with t_arg carries as many as the table has rows, in that order, and get_event_arg( n ) reads position n; a position that does not exist answers the empty string, and the whole list is client->get( )-t_event_arg:

)->a( n = `press` v = client->_event(
                        val   = `ROW_PRESS`
                        t_arg = VALUE #( ( `${$source>/title}` )
                                         ( `${$parameters>/id}` )
                                         ( `$event>sId` ) ) ) )

CASE client->get( )-event.
    WHEN `ROW_PRESS`.
        DATA(lv_title) = client->get_event_arg( ).
        DATA(lv_id)    = client->get_event_arg( 2 ).
        DATA(lv_type)  = client->get_event_arg( 3 ).
ENDCASE.

An argument that starts with $ or { is written into the view raw, as a live UI5 expression — that is how ${$source>/KEY} reaches the handler as the row's value. The flip side is that data which may start with those characters (text a user typed, a key from a foreign system) would be evaluated rather than passed. A wire that carries data rather than bindings sets s_ctrl-check_arg_literal, which quotes every argument of that wire as a string; see the next section.

The Per-Wire Options: s_ctrl

_event( ) takes a third parameter, s_ctrl, a structure of flags that are baked into the wire when the view is built. Each one answers a question a plain press never asks:

Flag	What it decides
check_queue_last	While a roundtrip is in flight, the last event fired on this wire is kept and dispatched once the response has landed, instead of being dropped. One roundtrip at a time, order preserved, and the backend ends on the control's current value. This is the flag for a per-keystroke wire — liveChange, liveSearch, sliderChange — which without it loses every keystroke typed while a roundtrip runs, the last one included
check_no_busy	Keeps the global busy indicator down for this wire. The roundtrip, the busy state and the guard are unchanged; only the full-screen overlay is not shown. For a per-keystroke wire the overlay is the wrong feedback — the user is looking at the field, not waiting for a screen — and from the second character on it flashes over the field. Pair it with check_queue_last: nothing is lost and nothing blinks
check_prevent_default	Cancels the control's built-in default for this event before the roundtrip (oEvent.preventDefault( )) — a sap.tnt NavigationListItem press that must not select the item, a Link that must not follow its href. The event is still sent, so the backend decides what happens instead
prevent_default_expr	The same veto decided per firing instead of per wire: a client expression evaluated when the event fires, which cancels the default only when it is truthy, e.g. ${$parameters>/column}.getId().indexOf('COL_DATE') >= 0 — one wire protects one column and lets the rest through. Wins over the flag when both are set
check_arg_literal	Quotes every argument of this wire as a string. The form for a wire whose arguments are data rather than bindings — see More Than One Argument above

The live search is the case that needs two of them at once:

)->tag( `SearchField`
    )->a( n = `value`      v = client->_bind( mv_search )
    )->a( n = `liveChange` v = client->_event(
                                 val    = `SEARCH`
                                 s_ctrl = VALUE #( check_queue_last = abap_true
                                                   check_no_busy    = abap_true ) ) )

Without the first flag the busy guard drops every keystroke that lands on a roundtrip already in flight, and the list stays at the value of the last completed roundtrip until the user pauses and types again. Without the second one the overlay flashes over the field while they type. Sample Z2UI5_CL_SMP_APP_059 on Tables is the live search written out in full.

A Control in Another View Slot

The forms above read the control that fired, the event object, or a bound model property. None of them reaches a different control — an id is local to the view or fragment it was written in, and a ${...} is a binding path, so it addresses data and never a control.

$controller.slotValue( slot, id, getter ) reads what a control in a named view slot currently holds. The classic case is a dialog whose value the button that closes it has to carry:

)->a( n = `press` v = client->_event(
                        val = `SAVE`
                        arg = `$controller.slotValue('POPUP','myEditor','getImagePngDataURL')` ) ).

CASE client->get( )-event.
    WHEN `SAVE`.
        DATA(image) = client->get_event_arg( ).
        client->popup_destroy( ).
ENDCASE.

The slot is one of the cs_view keys — MAIN, NEST, NEST2, POPUP, POPOVER — and an empty slot searches every open one and then the global registry, the same resolution cs_event-control_by_id uses for cs_view-main.

The getter takes no arguments on purpose. To call a control, use cs_event-control_by_id, which has a method whitelist in front of it; this is a read.

It never throws, it logs

A closed slot, an unknown id, a method the control does not have, or a getter that raises — each is written to the browser console and sent as the empty string. That is deliberate: an argument expression is evaluated while UI5 dispatches the handler, so an expression that throws loses the whole event, leaving a button that does nothing and an app with no way to tell.

$controller.slotById( slot, id ) hands the control itself over, for a null-tolerant reader such as $controller.textPath( ). It answers null on a miss — and a method call on that null is exactly the throw the tip above describes, so prefer slotValue( ) whenever you want a value.

$controller.textPath( control ) is the other helper that addresses the live control tree rather than data: it answers the ancestor-text breadcrumb of the control that fired — the titles and labels on the way up from it — so a handler can tell which panel or tab a press came from without an id of its own: arg = `$controller.textPath( ${$parameters>/item} )` .

Model Properties

Read model properties bound to the event:

CLASS zcl_sample_event_model DEFINITION PUBLIC.

  PUBLIC SECTION.
    INTERFACES z2ui5_if_app.
    DATA name TYPE string.

  PROTECTED SECTION.
  PRIVATE SECTION.
ENDCLASS.

CLASS zcl_sample_event_model IMPLEMENTATION.
  METHOD z2ui5_if_app~main.

    IF client->check_on_navigated( ).

      DATA(view) = z2ui5_cl_ui5_view_builder=>factory(
          )->ele( n = `View` ns = `mvc`
              )->a( n = `xmlns`     v = `sap.m`
              )->a( n = `xmlns:mvc` v = `sap.ui.core.mvc`

              )->ele( `Page`
                  )->tag( `Input`
                      )->a( n = `value` v = client->_bind( name )
                  )->tag( `Button`
                      )->a( n = `text`  v = `post`
                      )->a( n = `press` v = client->_event(
                                            val = `BUTTON_POST`
                                            arg = `$` && client->_bind( name ) ) ).

      client->view_display( view->stringify( ) ).

    ELSEIF client->check_on_event( `BUTTON_POST` ).
      client->message_box_display( |The name is { client->get_event_arg( ) }| ).

    ENDIF.

ENDMETHOD.

ENDCLASS.

TIP

This is just a demo. Reading name directly would be easier — the framework updates it automatically.

Working Samples

Complete apps from the sample catalog that use what this page describes. Each is a single class in abap2UI5/samples unless its row names another of the three sample repositories — pull that repository with abapGit and start the class with ?app_start=<class>.

Sample	Class
Extra Arguments with t_arg	Z2UI5_CL_SMP_APP_167
Control Objects in t_arg (FacetFilter)	Z2UI5_CL_SMP_APP_197