ui: add a workaround for JavaGUI dyn form bug (#2873)

JavaGUI does not pass values of options from forms generated via
JavaScript.

This commit adds enhances the base page class to render stub forms
(empty form elements), so the page's JavaScript does not need to create
the form element on its own.

It is an optional behavior and can be enabled by redefining the method
get_events which should return table of required events and the base
page object will add the empty form elements for them. Every table line
will be converted to a form with id = "form_" + the event's name.

On the action submit SAP event in the common JavaScript, the method
checks if there is the stub form and if so, the method uses it instead
of creating the dynamic one. Otherwise, it follows the old approach that
creates the form at run-time.

--- v2

Use 'null' instead of 'undefined' to check the form was not found in
the JavaScript code.

---

Issues: #1866, #2769

src/ui/zabapgit_js_common.w3mi.data.js

@@ -93,11 +93,17 @@ function debugOutput(text, dstID) {
   stdout.innerHTML = stdout.innerHTML + wrapped;
 }
 
-// Create hidden form and submit with sapevent
+// Use a pre-created form or create a hidden form
+// and submit with sapevent
 function submitSapeventForm(params, action, method) {
-  var form = document.createElement("form");
+  var stub_form_id = "form_" + action;
-  form.setAttribute("method", method || "post");
+  var form = document.getElementById(stub_form_id);
-  form.setAttribute("action", "sapevent:" + action);
+
+  if (form === null) {
+    form = document.createElement("form");
+    form.setAttribute("method", method || "post");
+    form.setAttribute("action", "sapevent:" + action);
+  }
 
   for(var key in params) {
     var hiddenField = document.createElement("input");
@@ -107,7 +113,10 @@ function submitSapeventForm(params, action, method) {
     form.appendChild(hiddenField);
   }
 
-  document.body.appendChild(form);
+  if (form.id !== stub_form_id) {
+    document.body.appendChild(form);
+  }
+
   form.submit();
 }
 

src/ui/zcl_abapgit_gui_page.clas.abap

@@ -28,12 +28,28 @@ CLASS zcl_abapgit_gui_page DEFINITION PUBLIC ABSTRACT CREATE PUBLIC.
              page_menu    TYPE REF TO zcl_abapgit_html_toolbar,
            END OF  ty_control.
 
+    TYPES: BEGIN OF ty_event,
+             method TYPE string,
+             name TYPE string,
+           END OF  ty_event.
+
+    TYPES: tt_events TYPE STANDARD TABLE OF ty_event WITH DEFAULT KEY.
+
     DATA: ms_control TYPE ty_control.
 
     METHODS render_content ABSTRACT
       RETURNING VALUE(ro_html) TYPE REF TO zcl_abapgit_html
       RAISING   zcx_abapgit_exception.
 
+    METHODS get_events
+      RETURNING VALUE(rt_events) TYPE tt_events
+      RAISING   zcx_abapgit_exception.
+
+    METHODS render_event_as_form
+      IMPORTING is_event TYPE ty_event
+      RETURNING VALUE(ro_html) TYPE REF TO zcl_abapgit_html
+      RAISING   zcx_abapgit_exception.
+
     METHODS scripts
       RETURNING VALUE(ro_html) TYPE REF TO zcl_abapgit_html
       RAISING   zcx_abapgit_exception.
@@ -346,6 +362,19 @@ CLASS ZCL_ABAPGIT_GUI_PAGE IMPLEMENTATION.
 
   ENDMETHOD.
 
+  METHOD get_events.
+
+    " Return actions you need on your page.
+
+  ENDMETHOD.
+
+  METHOD render_event_as_form.
+
+    CREATE OBJECT ro_html.
+    ro_html->add(
+      |<form id='form_{ is_event-name }' method={ is_event-method } action='sapevent:{ is_event-name }'></from>| ).
+
+  ENDMETHOD.
 
   METHOD scripts.
 
@@ -434,7 +463,11 @@ CLASS ZCL_ABAPGIT_GUI_PAGE IMPLEMENTATION.
 
   METHOD zif_abapgit_gui_renderable~render.
 
-    DATA: lo_script TYPE REF TO zcl_abapgit_html.
+    DATA: lo_script TYPE REF TO zcl_abapgit_html,
+          lt_events TYPE zcl_abapgit_gui_page=>tt_events.
+
+    FIELD-SYMBOLS:
+          <ls_event> LIKE LINE OF lt_events.
 
     " Redirect
     IF ms_control-redirect_url IS NOT INITIAL.
@@ -455,6 +488,12 @@ CLASS ZCL_ABAPGIT_GUI_PAGE IMPLEMENTATION.
     ro_html->add( render_hotkey_overview( ) ).
     ro_html->add( render_content( ) ).
     ro_html->add( render_error_message_box( ) ).
+
+    lt_events = me->get_events( ).
+    LOOP AT lt_events ASSIGNING <ls_event>.
+      ro_html->add( render_event_as_form( <ls_event> ) ).
+    ENDLOOP.
+
     ro_html->add( footer( ) ).
     ro_html->add( '</body>' ).                              "#EC NOTEXT
 

src/ui/zcl_abapgit_gui_page_stage.clas.abap

@@ -23,6 +23,7 @@ CLASS zcl_abapgit_gui_page_stage DEFINITION
   PROTECTED SECTION.
     METHODS:
       render_content REDEFINITION,
+      get_events     REDEFINITION,
       scripts        REDEFINITION.
 
   PRIVATE SECTION.
@@ -147,7 +148,6 @@ CLASS ZCL_ABAPGIT_GUI_PAGE_STAGE IMPLEMENTATION.
 
   ENDMETHOD.
 
-
   METHOD find_transports.
     DATA: li_cts_api TYPE REF TO zif_abapgit_cts_api,
           ls_new     LIKE LINE OF rt_transports.
@@ -183,6 +183,17 @@ CLASS ZCL_ABAPGIT_GUI_PAGE_STAGE IMPLEMENTATION.
       CATCH zcx_abapgit_exception.
         ASSERT 1 = 2.
     ENDTRY.
+
+  ENDMETHOD.
+
+  METHOD get_events.
+
+    FIELD-SYMBOLS: <ls_event> TYPE zcl_abapgit_gui_page=>ty_event.
+
+    APPEND INITIAL LINE TO rt_events ASSIGNING <ls_event>.
+    <ls_event>-method = 'post'.
+    <ls_event>-name = 'stage_commit'.
+
   ENDMETHOD.