Step 4: Data Binding

So far the app only talks. Now the user answers: an input field replaces the text, and whatever is typed into it arrives in your class — without a single line of transfer code:

CLASS zcl_app_walkthrough DEFINITION PUBLIC.
  PUBLIC SECTION.
    INTERFACES z2ui5_if_app.
    DATA recipient TYPE string.
ENDCLASS.

CLASS zcl_app_walkthrough IMPLEMENTATION.
  METHOD z2ui5_if_app~main.

    IF client->check_on_navigated( ).

      recipient = `World`.

      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( `Shell`
                  )->ele( `Page`
                      )->a( n = `title` v = `Walkthrough - Step 4`

                      )->tag( `Input`
                          )->a( n = `value` v = client->_bind( recipient )
                      )->tag( `Button`
                          )->a( n = `text`  v = `Say Hello`
                          )->a( n = `press` v = client->_event( `SAY_HELLO` ) ).

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

    ELSEIF client->check_on_event( `SAY_HELLO` ).

      client->message_toast_display( |Hello { recipient }!| ).

    ENDIF.

  ENDMETHOD.
ENDCLASS.

How the Value Travels

• DATA recipient TYPE string — a public attribute is the model. After every roundtrip the framework serializes the whole app instance into a draft on the server and restores it before the next one, so your class keeps its state without any session handling. Attributes you _bind( ) must be in the PUBLIC SECTION — the framework reaches them dynamically, and a private or protected one fails the roundtrip with BINDING_ERROR. (Everything else may stay protected; it is serialized either way. Full rules on the Binding page.)
• client->_bind( recipient ) connects the attribute to the value property of the input. When the button fires, the browser sends the current screen state along with the event — by the time your ELSEIF branch runs, recipient already holds what the user typed.
• Type it, press the button — the toast greets whatever name is in the field. Both directions, and you wrote no transfer code.

Next, the same binding moves a whole internal table into a list.

Working Samples

Complete apps from the sample catalogue that use what this page describes. Each is a single class — pull the repository with abapGit and start it with ?app_start=<class>.

Sample	Class
Basics II — Data Binding: Input and Button	Z2UI5_CL_SMP_APP_494