Editable ALV: editing and validation without drama

This is where CL_SALV_TABLE falls short and you drop down to CL_GUI_ALV_GRID. An editable ALV is not just putting cells in write mode: it is validating what the user types, offering value helps and persisting only what is correct. And all of that runs through events. Let us go to the real pattern.

Validate on the fly: the data_changed event

Every time the user modifies a cell, the grid fires data_changed. There you loop over the changed cells (mt_good_cells), read the value and decide whether it is valid. If it is not, you do not throw a dump: you register the error in the ALV’s own protocol.

METHOD handle_data_changed.
  DATA: ls_data_changed TYPE lvc_s_modi,
        lv_marca        TYPE zlo_marca.

  LOOP AT er_data_changed->mt_good_cells INTO ls_data_changed.
    CASE ls_data_changed-fieldname.
      WHEN 'MARCA'.
        er_data_changed->get_cell_value(
          EXPORTING
            i_row_id    = ls_data_changed-row_id
            i_fieldname = ls_data_changed-fieldname
          IMPORTING
            e_value     = lv_marca ).

        SELECT SINGLE marca FROM zco_marcas
          INTO lv_marca
          WHERE marca EQ lv_marca.
        IF sy-subrc NE 0.
          er_data_changed->add_protocol_entry(
            EXPORTING
              i_msgid     = 'ZCO_MSG'
              i_msgty     = 'E'
              i_msgno     = '000'
              i_msgv1     = text-m01
              i_msgv2     = lv_marca
              i_fieldname = ls_data_changed-fieldname
              i_row_id    = ls_data_changed-row_id ).
        ENDIF.
    ENDCASE.
  ENDLOOP.
ENDMETHOD.

add_protocol_entry is the key piece: it flags the cell in red and shows the message in the ALV’s standard protocol, without pulling the user out of context. The brand does not exist in zco_marcas -> visible error, edit not confirmed.

flowchart TB
  U["User edits MARCA cell"] --> DC["data_changed event"]
  DC --> V["SELECT SINGLE on zco_marcas"]
  V -->|"exists"| OK["cell accepted"]
  V -->|"missing"| ER["add_protocol_entry - cell in red"]
  OK --> DCF["data_changed_finished - flags row as modified"]

Custom value help: the onf4 event

For editable cells it pays to offer a tailored F4. You declare the column with f4availabl = abap_true in the catalog and implement onf4, which fills the values and returns them to the grid via er_event_data:

METHOD handle_onf4.
  DATA: lt_marcas     TYPE TABLE OF zco_marcas,
        lt_return_tab TYPE TABLE OF ddshretval,
        ls_return_tab TYPE ddshretval,
        ls_modify_data TYPE lvc_s_modi.
  FIELD-SYMBOLS <lt_modify_data> TYPE lvc_t_modi.

  CASE e_fieldname.
    WHEN 'MARCA'.
      SELECT marca FROM zco_marcas INTO TABLE lt_marcas WHERE marca NE space.
      CALL FUNCTION 'F4IF_INT_TABLE_VALUE_REQUEST'
        EXPORTING
          retfield    = 'MARCA'
          dynpprog    = sy-repid
          dynpnr      = sy-dynnr
          dynprofield = 'MARCA'
          value_org   = 'S'
        TABLES
          value_tab   = lt_marcas
          return_tab  = lt_return_tab.
      READ TABLE lt_return_tab INTO ls_return_tab INDEX 1.
      IF sy-subrc EQ 0.
        ls_modify_data-row_id    = es_row_no-row_id.
        ls_modify_data-fieldname = e_fieldname.
        ls_modify_data-value     = ls_return_tab-fieldval.
        ASSIGN er_event_data->m_data->* TO <lt_modify_data>.
        APPEND ls_modify_data TO <lt_modify_data>.
      ENDIF.
  ENDCASE.
  er_event_data->m_event_handled = abap_true.
ENDMETHOD.

Do not forget er_event_data->m_event_handled = abap_true: it tells the grid you have handled the F4 and it should not apply the standard one.

Persist only what is good

You flag the touched rows in data_changed_finished (with your own flag, here bbdd), and on “Save” you loop over only those and run MODIFY:

WHEN 'A_SAVE'.
  LOOP AT gt_vehiculos INTO ls_vehiculos WHERE bbdd EQ abap_true.
    MOVE-CORRESPONDING ls_vehiculos TO ls_bbdd_vehiculos.
    APPEND ls_bbdd_vehiculos TO lt_bbdd_vehiculos.
  ENDLOOP.
  IF sy-subrc EQ 0.
    MODIFY zco_vehiculos FROM TABLE lt_bbdd_vehiculos.
    IF sy-subrc EQ 0.
      MESSAGE s001(zco_msg).
    ENDIF.
  ENDIF.

An editable ALV without validation in data_changed is not a convenience: it is a direct route to shoving garbage into the database.

Next post we close the series with what holds all of this up: the field catalog, the layout and the variants the user saves and expects to find again.