Manual Field Catalog and Report Events (Program 2)

ABAP Reports Series · Blog 6 of 15

Manual Field Catalog and Report Events (Program 2)

Beginner to intermediate · 16 min read · Needs Blog 5

1. Why a manual field catalog?

In Blog 5, ALV built the field catalog from a dictionary structure. That is quick, but it has limits. You need a manual catalog when you want to:

Use a local type instead of a dictionary structure (no SE11 needed).
Show a calculated column that is not in the database, such as a status text.
Choose your own column headings and order.
Hide columns, mark key columns, or add totals.
Control column width and alignment.

2. SLIS_FIELDCAT_ALV: the essential fields

The field catalog is an internal table of type slis_t_fieldcat_alv. Each row is a structure of type slis_fieldcat_alv and describes one column.

Field	Purpose
`fieldname`	Column name in your output table. Use capitals.
`tabname`	Name of the output table in capitals, for example `'GT_VBAK'`.
`col_pos`	Column position, starting at 1.
`seltext_s` / `_m` / `_l`	Short, medium and long headings.
`outputlen`	Width in characters.
`key`	`'X'` marks a key column. It is highlighted and stays fixed when scrolling.
`do_sum`	`'X'` shows a total for a numeric column.
`cfieldname`	Name of the currency field for an amount column.
`no_out`	`'X'` hides the column by default. The user can show it later.
`just`	Alignment: `'L'`, `'R'` or `'C'`.
`hotspot`	`'X'` makes cells clickable (used in Blog 10).

3. The pattern for building a catalog

For each column, fill one structure and append it. A small helper routine avoids repeating the same lines.

" Long way: one column
DATA ls_fcat TYPE slis_fieldcat_alv.

ls_fcat-fieldname = 'VBELN'.
ls_fcat-tabname   = 'GT_VBAK'.
ls_fcat-col_pos   = 1.
ls_fcat-seltext_m = 'Sales Doc.'.
ls_fcat-outputlen = 10.
ls_fcat-key       = 'X'.
APPEND ls_fcat TO gt_fcat.
CLEAR ls_fcat.

Always CLEAR the structure

If you reuse ls_fcat for the next column without clearing it, settings such as key leak into columns that should not have them.

4. Report events: the lifecycle

A report is not read top to bottom. ABAP runs event blocks in a fixed order. Code placed under an event runs only when that event is triggered.

Order	Event	Runs when	Typical use
1	`LOAD-OF-PROGRAM`	Program is loaded	Rare
2	`INITIALIZATION`	Before the selection screen appears	Set default values
3	`AT SELECTION-SCREEN OUTPUT`	Each time the screen is shown	Show or hide fields (Blog 7)
4	`AT SELECTION-SCREEN`	User presses Enter or F8	Validate input
5	`START-OF-SELECTION`	User presses F8	Read data, main logic
6	`END-OF-SELECTION`	All data is processed	Display the result
7	`TOP-OF-PAGE`	A new list page starts	Page header (classical lists)
8	`AT LINE-SELECTION`	User double-clicks a list line	Drill-down (Blogs 8 and 9)

Do not use the same event twice

Each event may appear once. Statements written before any event are treated as part of START-OF-SELECTION, which can cause confusing behaviour. Always write the event keyword explicitly.

5. Program 2: full code

This report uses a local type, a calculated column (VBTXT), a manual field catalog, and an ALV header.

REPORT zalv_program2.

*---------------------------------------------------------------------*
* Types and data
*---------------------------------------------------------------------*
TYPES: BEGIN OF ty_vbak,
         vbeln TYPE vbak-vbeln,
         erdat TYPE vbak-erdat,
         ernam TYPE vbak-ernam,
         vbtyp TYPE vbak-vbtyp,
         vbtxt TYPE c LENGTH 15,    " calculated, not in the database
         netwr TYPE vbak-netwr,
         waerk TYPE vbak-waerk,
       END OF ty_vbak.

DATA: gt_vbak   TYPE STANDARD TABLE OF ty_vbak WITH DEFAULT KEY,
      gt_fcat   TYPE slis_t_fieldcat_alv,
      gs_layout TYPE slis_layout_alv,
      gv_repid  TYPE sy-repid,
      gv_erdat  TYPE vbak-erdat.

*---------------------------------------------------------------------*
* Selection screen
*---------------------------------------------------------------------*
SELECT-OPTIONS s_erdat FOR gv_erdat.
PARAMETERS p_max TYPE i DEFAULT 500.

*---------------------------------------------------------------------*
* Events
*---------------------------------------------------------------------*
INITIALIZATION.
  s_erdat-sign   = 'I'.
  s_erdat-option = 'BT'.
  s_erdat-low    = sy-datum - 30.
  s_erdat-high   = sy-datum.
  APPEND s_erdat.

AT SELECTION-SCREEN.
  IF p_max <= 0.
    MESSAGE 'Maximum rows must be greater than zero' TYPE 'E'.
  ENDIF.

START-OF-SELECTION.
  PERFORM get_data.

END-OF-SELECTION.
  IF gt_vbak IS NOT INITIAL.
    PERFORM build_fieldcat.
    PERFORM display_alv.
  ENDIF.

*---------------------------------------------------------------------*
* FORM get_data: read data and fill the calculated column
*---------------------------------------------------------------------*
FORM get_data.
  SELECT vbeln, erdat, ernam, vbtyp, netwr, waerk
    FROM vbak
    WHERE erdat IN @s_erdat
    ORDER BY erdat DESCENDING, vbeln
    INTO CORRESPONDING FIELDS OF TABLE @gt_vbak
    UP TO @p_max ROWS.

  IF sy-subrc <> 0.
    MESSAGE 'No sales orders found for your selection'
            TYPE 'S' DISPLAY LIKE 'E'.
    RETURN.
  ENDIF.

  LOOP AT gt_vbak ASSIGNING FIELD-SYMBOL(<ls_vbak>).
    <ls_vbak>-vbtxt = SWITCH #( <ls_vbak>-vbtyp
                          WHEN 'A' THEN 'Inquiry'
                          WHEN 'B' THEN 'Quotation'
                          WHEN 'C' THEN 'Order'
                          ELSE         'Other' ).
  ENDLOOP.
ENDFORM.

*---------------------------------------------------------------------*
* FORM add_col: helper to add one column to the field catalog
*---------------------------------------------------------------------*
FORM add_col USING pv_field TYPE slis_fieldname
                    pv_text  TYPE scrtext_m
                    pv_len   TYPE i
                    pv_key   TYPE c.
  DATA ls_fcat TYPE slis_fieldcat_alv.

  ls_fcat-fieldname = pv_field.
  ls_fcat-tabname   = 'GT_VBAK'.
  ls_fcat-col_pos   = lines( gt_fcat ) + 1.
  ls_fcat-seltext_s = pv_text.
  ls_fcat-seltext_m = pv_text.
  ls_fcat-seltext_l = pv_text.
  ls_fcat-outputlen = pv_len.
  ls_fcat-key       = pv_key.
  APPEND ls_fcat TO gt_fcat.
ENDFORM.

*---------------------------------------------------------------------*
* FORM build_fieldcat: define all columns
*---------------------------------------------------------------------*
FORM build_fieldcat.
  DATA ls_fcat TYPE slis_fieldcat_alv.

  PERFORM add_col USING 'VBELN' 'Sales Doc.'  12 'X'.
  PERFORM add_col USING 'ERDAT' 'Created on'  12 ''.
  PERFORM add_col USING 'ERNAM' 'Created by'  12 ''.
  PERFORM add_col USING 'VBTYP' 'Cat.'        5  ''.
  PERFORM add_col USING 'VBTXT' 'Category'    15 ''.

  " Amount column: needs a currency field and a total
  ls_fcat-fieldname  = 'NETWR'.
  ls_fcat-tabname    = 'GT_VBAK'.
  ls_fcat-col_pos    = lines( gt_fcat ) + 1.
  ls_fcat-seltext_s  = 'Net value'.
  ls_fcat-seltext_m  = 'Net value'.
  ls_fcat-seltext_l  = 'Net value'.
  ls_fcat-outputlen  = 16.
  ls_fcat-cfieldname = 'WAERK'.
  ls_fcat-do_sum     = 'X'.
  APPEND ls_fcat TO gt_fcat.
  CLEAR ls_fcat.

  PERFORM add_col USING 'WAERK' 'Currency' 8 ''.
ENDFORM.

*---------------------------------------------------------------------*
* FORM display_alv
*---------------------------------------------------------------------*
FORM display_alv.
  gv_repid = sy-repid.
  gs_layout-zebra             = 'X'.
  gs_layout-colwidth_optimize = 'X'.

  CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY'
    EXPORTING
      i_callback_program     = gv_repid
      i_callback_top_of_page = 'ALV_TOP_OF_PAGE'
      is_layout              = gs_layout
      it_fieldcat            = gt_fcat
    TABLES
      t_outtab               = gt_vbak
    EXCEPTIONS
      program_error          = 1
      OTHERS                 = 2.

  IF sy-subrc <> 0.
    MESSAGE 'ALV could not be displayed' TYPE 'S' DISPLAY LIKE 'E'.
  ENDIF.
ENDFORM.

*---------------------------------------------------------------------*
* FORM alv_top_of_page: ALV header (called by ALV itself)
*---------------------------------------------------------------------*
FORM alv_top_of_page.
  DATA lt_header TYPE slis_t_listheader.
  DATA ls_header TYPE slis_listheader.

  " Title
  ls_header-typ  = 'H'.
  ls_header-info = 'Sales Orders Report'.
  APPEND ls_header TO lt_header.
  CLEAR ls_header.

  " Selection info
  ls_header-typ  = 'S'.
  ls_header-key  = 'Period:'.
  ls_header-info = |{ s_erdat-low DATE = USER } to { s_erdat-high DATE = USER }|.
  APPEND ls_header TO lt_header.
  CLEAR ls_header.

  ls_header-typ  = 'S'.
  ls_header-key  = 'Records:'.
  ls_header-info = |{ lines( gt_vbak ) }|.
  APPEND ls_header TO lt_header.
  CLEAR ls_header.

  " Action line (shown in italics)
  ls_header-typ  = 'A'.
  ls_header-info = |Run by { sy-uname } on { sy-datum DATE = USER }|.
  APPEND ls_header TO lt_header.

  CALL FUNCTION 'REUSE_ALV_COMMENTARY_WRITE'
    EXPORTING
      it_list_commentary = lt_header.
ENDFORM.

6. Walkthrough

Part	What it does
`TYPES ty_vbak`	A local structure. No SE11 object is needed. It includes `VBTXT`, which does not exist in the database.
`START-OF-SELECTION`	Reads the data.
`END-OF-SELECTION`	Runs after the data is ready, so it builds the catalog and shows the grid.
`SWITCH` in `get_data`	Fills the calculated category text for each row.
`add_col`	A helper that builds one catalog row, so the catalog stays short and readable.
`NETWR` row	Sets `cfieldname` so amounts display with the right decimals, and `do_sum` for a total.
`tabname = 'GT_VBAK'`	Must match the output table name in capitals.
`is_layout`	Zebra stripes and optimized widths. Blog 10 covers layouts in depth.
`i_callback_top_of_page`	Names the form ALV calls to draw the header.

Why is the currency column still in the table?

cfieldname = 'WAERK' points to a column of the output table. That column must exist in the table, even if you decide to hide it with no_out.

The header is a table of lines of type slis_t_listheader. Each line has a type that controls its style:

typ	Style	Fields used
`H`	Large heading	`info`
`S`	Selection information, shown as label and value	`key` and `info`
`A`	Action text, shown in italics	`info`

After filling the table, call REUSE_ALV_COMMENTARY_WRITE inside the callback form. The header appears above the grid on every display.

8. TOP-OF-PAGE vs. ALV header

	Classical `TOP-OF-PAGE`	ALV header
Used with	`WRITE` lists	ALV grid
How it is triggered	Event keyword in your program	Callback named in `i_callback_top_of_page`
Content	`WRITE` statements	A header table and `REUSE_ALV_COMMENTARY_WRITE`
Form name	No form, an event block	Any form name you choose

Do not mix them up

The TOP-OF-PAGE event does not draw the header of an ALV grid. For a grid you must use the callback form. That is why the form here is named alv_top_of_page.

9. Try it yourself

Hide the VBTYP column by default with no_out = 'X', then show it again from the layout settings.
Right-align the Created by column with just = 'R'.
Change the order of the columns by editing the PERFORM add_col lines.
Add a second S line to the header showing the user’s selected maximum rows.
Add a new calculated column Size showing 'Large' when netwr is above 10,000.

10. Common mistakes

Wrong tabname. It must be the output table name in capitals. Otherwise columns are missing.
Lowercase fieldname. Use 'VBELN', not 'vbeln'.
Not clearing ls_fcat between columns, so settings carry over.
Missing currency column when cfieldname is set.
Duplicate col_pos values. Columns jump around or disappear.
Header form name misspelled in i_callback_top_of_page. The header is simply missing.
Header form in another program. Callback forms must be in the same program as i_callback_program.
Expecting the TOP-OF-PAGE event to draw the grid header. Use the callback instead.

Up next: Blog 7

Dynamic Selection Screens. Show and hide fields while the user is working, using AT SELECTION-SCREEN OUTPUT and LOOP AT SCREEN.

Cart

Cart

Manual Field Catalog + Report Events (Program 2)

Manual Field Catalog and Report Events (Program 2)

1. Why a manual field catalog?

2. SLIS_FIELDCAT_ALV: the essential fields

3. The pattern for building a catalog

4. Report events: the lifecycle

5. Program 2: full code

6. Walkthrough

7. The ALV header

8. TOP-OF-PAGE vs. ALV header

9. Try it yourself

10. Common mistakes

Up next: Blog 7