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Hello World

Basic Example

Every abap2UI5 app is an implementation of the Z2UI5_IF_APP interface. Create a new class with the following code:

abap
CLASS zcl_app_hello_world DEFINITION PUBLIC.

  PUBLIC SECTION.
    INTERFACES z2ui5_if_app.

ENDCLASS.

CLASS zcl_app_hello_world IMPLEMENTATION.
  METHOD z2ui5_if_app~main.

    client->message_box_display( `Hello World` ).
    
  ENDMETHOD.
ENDCLASS.

Head back to the landing page in your browser and enter Z2UI5_CL_APP_HELLO_WORLD to launch your app.

View Display

Now, let's add our first view to display a simple text:

abap
CLASS z2ui5_cl_app_hello_world DEFINITION PUBLIC.
  PUBLIC SECTION.
    INTERFACES z2ui5_if_app.
ENDCLASS.

CLASS z2ui5_cl_app_hello_world IMPLEMENTATION.
  METHOD z2ui5_if_app~main.

    DATA(view) = z2ui5_cl_xml_view=>factory(
      )->page( `abap2UI5 - Hello World`
      )->text( `My Text` ).
    client->view_display( view->stringify( ) ).

  ENDMETHOD.
ENDCLASS.

Event Handler

Next, we extend the app with a button and an event handler. To ensure that the view is only rendered at the start, we also check for the on_init event:

abap
CLASS z2ui5_cl_app_hello_world DEFINITION PUBLIC.
  PUBLIC SECTION.
    INTERFACES z2ui5_if_app.
ENDCLASS.

CLASS z2ui5_cl_app_hello_world IMPLEMENTATION.
  METHOD z2ui5_if_app~main.

    CASE abap_true.

      WHEN client->check_on_init( ).

        DATA(view) = z2ui5_cl_xml_view=>factory(
          )->page( `abap2UI5 - Hello World`
          )->text( `My Text`
          )->button( text = `post` press = client->_event( `POST` ) ).
        client->view_display( view->stringify( ) ).

      WHEN client->check_on_event( `POST` ).

        client->message_box_display( `Hello World!` ).

    ENDCASE.

  ENDMETHOD.
ENDCLASS.

Data Exchange

Finally, we add a public attribute and can send data to the backend:

abap
CLASS z2ui5_cl_app_hello_world DEFINITION PUBLIC.
  PUBLIC SECTION.
    INTERFACES z2ui5_if_app.
    DATA name TYPE string.
ENDCLASS.

CLASS z2ui5_cl_app_hello_world IMPLEMENTATION.
  METHOD z2ui5_if_app~main.

    CASE abap_true.

      WHEN client->check_on_init( ).

        DATA(view) = z2ui5_cl_xml_view=>factory( 
          )->page( `abap2UI5 - Hello World` 
          )->text( `My Text` 
          )->button(
            text  = `post`
            press = client->_event( `POST` )
          )->input( client->_bind_edit( name ) ).
        client->view_display( view->stringify( ) ).

      WHEN client->check_on_event( `POST` ).

        client->message_box_display( |Your name is { name }.| ).

    ENDCASE.

  ENDMETHOD.
ENDCLASS.

And that's it! Set a breakpoint to observe the communication and data updates in action. Now you can play around and experiment with modifying the view, events, and data exchange.

ABAP Language Versions

While you need to distinguish between Standard ABAP and ABAP for Cloud in the HTTP Handler, the apps themselves are independent. You're free to decide whether to develop your apps with ABAP Cloud compatibility or not.