Basics II

" @keywords binding _bind model attribute value input button roundtrip messagebox serialize
" @summary Binds a class attribute to an Input with _bind( ), so what the user types is in the ABAP variable on the next roundtrip - a Text shows it back and a MessageBox confirms the roundtrip.
" @docs https://abap2ui5.github.io/docs/cookbook/model/binding https://abap2ui5.github.io/docs/tutorials/walkthrough/step-4
CLASS z2ui5_cl_smp_app_494 DEFINITION PUBLIC.

  PUBLIC SECTION.
    INTERFACES z2ui5_if_app.

    DATA name     TYPE string.
    DATA greeting TYPE string.

  PROTECTED SECTION.
    DATA client TYPE REF TO z2ui5_if_client.

    METHODS view_display.

  PRIVATE SECTION.
ENDCLASS.


CLASS z2ui5_cl_smp_app_494 IMPLEMENTATION.

  METHOD z2ui5_if_app~main.

    me->client = client.
    IF client->check_on_init( ).
      name = `World`.
      view_display( ).
    ELSEIF client->check_on_navigated( ).
      view_display( ).
    ELSEIF client->check_on_event( `GREET` ).
      greeting = |Hello { name }!|.
      client->message_box_display( |Roundtrip done: the backend read NAME = '{ name }' and wrote GREETING back into the view.| ).
    ENDIF.

  ENDMETHOD.


  METHOD view_display.

    DATA(view) = z2ui5_cl_ui5_view_builder=>factory(
        )->ele( n = `View` ns = `mvc`
            )->a( n = `displayBlock` v = `true`
            )->a( n = `height`       v = `100%`
            )->a( n = `xmlns`        v = `sap.m`
            )->a( n = `xmlns:mvc`    v = `sap.ui.core.mvc`
            )->a( n = `xmlns:core`   v = `sap.ui.core`
            )->a( n = `xmlns:form`   v = `sap.ui.layout.form` ).
    DATA(page) = view->ele( `Shell`
        )->ele( `Page`
            )->a( n = `title`          v = `abap2UI5 - Basics II - Data Binding: Input and Button`
            )->a( n = `showNavButton`  b = client->check_app_prev_stack( )
            )->a( n = `navButtonPress` v = client->_event_nav_app_leave( ) ).

    page->tag( `MessageStrip`
        )->a( n = `text`     v = `client->_bind( name ) connects the public attribute NAME with the input ` &&
                   `below. Type a name and leave the field: the text ` &&
                   `next to it changes without any ABAP code, because both are bound to the ` &&
                   `same attribute. Press Greet and the backend reads NAME - already filled ` &&
                   `in, no event argument needed -, writes GREETING back into the view and ` &&
                   `confirms the roundtrip with a MessageBox.`
        )->a( n = `type`     v = `Information`
        )->a( n = `showIcon` b = abap_true
        )->a( n = `class`    v = `sapUiSmallMargin` ).

    page->ele( n = `SimpleForm` ns = `form`
        )->a( n = `title`    v = `Data Binding`
        )->a( n = `editable` b = abap_true
        )->ele( n = `content` ns = `form`
            )->tag( `Label`
                )->a( n = `text` v = `your name`
            )->tag( `Input`
                )->a( n = `value` v = client->_bind( name )
            )->tag( `Label`
                )->a( n = `text` v = `bound to the same attribute`
            )->tag( `Text`
                )->a( n = `text` v = client->_bind( name )
            )->tag( `Label`
                )->a( n = `text` v = `written by the backend`
            )->tag( `Text`
                )->a( n = `text` v = client->_bind( greeting )
            )->tag( `Button`
                )->a( n = `press` v = client->_event( `GREET` )
                )->a( n = `text`  v = `Greet` ).
    client->view_display( view->stringify( ) ).

  ENDMETHOD.
ENDCLASS.