ALV Reports Part 3: OO ALV with CL_GUI_ALV_GRID and a Custom Container

📌 KEY POINTS
✅ CL_GUI_ALV_GRID is a GUI control placed in a container on your own dynpro screen.
✅ Flow: CALL SCREEN 100 → PBO creates container + grid once → set_table_for_first_display → PAI handles OK codes.
✅ It uses LVC types (lvc_t_fcat, lvc_s_layo) — not the SLIS types of REUSE_ALV.
⚠️ Create container and grid only once (IF go_grid IS INITIAL); later use refresh_table_display.

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▶ WHERE WE ARE
Parts 1–2 were full-screen ALVs without own screens. CL_GUI_ALV_GRID gives full control — events (Part 6, 8), editing (Part 9), several grids on one screen.

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▶ 1. BUILDING BLOCKS

• Screen 100 (SE51 or from SE80) with a Custom Control element named e.g. CC_ALV.
• GUI status (SE41) with BACK/EXIT/CANCEL functions, set in PBO.
• Container: CL_GUI_CUSTOM_CONTAINER EXPORTING container_name = 'CC_ALV'. (Alternative: CL_GUI_DOCKING_CONTAINER — no screen element needed.)
• Grid: CL_GUI_ALV_GRID EXPORTING i_parent = go_container.

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▶ 2. FIELD CATALOG AND LAYOUT (LVC)

• LVC_FIELDCATALOG_MERGE with i_structure_name builds lvc_t_fcat from DDIC; then adjust coltext, outputlen, do_sum.
• lvc_s_layo: zebra, cwidth_opt, sel_mode ('A' for multi-row selection), grid_title.

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▶ 3. FIRST DISPLAY AND REFRESH
go_grid->set_table_for_first_display( EXPORTING is_layout = gs_layout CHANGING it_outtab = gt_out it_fieldcatalog = gt_fcat ).

• Called once. After changing gt_out, call go_grid->refresh_table_display( ) — optionally with is_stable to keep scroll position.

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▶ 4. SCREEN FLOW
PBO: SET PF-STATUS, SET TITLEBAR, create ALV if initial.
PAI: CASE ok_code — BACK/EXIT → LEAVE TO SCREEN 0; free controls on exit (go_container->free( )).

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▶ 5. WHY STILL USE IT
Most custom Z transactions with ALV in ECC and S/4 on-premise use this pattern; you will maintain it in support projects.

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▶ STEP BY STEP

1. Create report ZALV_GRID_OO with screen 100 (custom control CC_ALV) and status STATUS_100 (BACK, EXIT, CANCEL).
2. Paste the code example and activate everything.
3. Add a REFRESH function in the status: re-select data and call refresh_table_display.

💡 Tip: CL_GUI_DOCKING_CONTAINER EXPORTING extension = 2000 lets you place an ALV on a selection screen or without a screen element.

✅ CHECKPOINT: you can build and maintain a screen-based ALV with CL_GUI_ALV_GRID.

A support ticket reported that a custom goods receipt transaction became slower each time the user pressed Refresh, and eventually the GUI froze. The PBO module created a new container and grid on every screen round trip, stacking dozens of controls.
The fix was the standard pattern: create container and grid only IF go_grid IS INITIAL, and use refresh_table_display with is_stable afterwards. The container was freed on BACK. Response time returned to normal.

• Creating container/grid in every PBO.
• Custom control name in the screen not matching container_name.
• Calling set_table_for_first_display again instead of refresh_table_display.
• Output table declared locally (grid keeps a reference).
• Not clearing the OK code or not freeing controls on exit.

• Create controls once, refresh afterwards with is_stable.
• Build the LVC catalog from DDIC and adjust in a loop with field symbols.
• Keep the output table global or as a class attribute.
• Use a docking container when no screen layout is needed.
• Encapsulate ALV handling in a local class for larger reports.

Questions: "How do you display an ALV with CL_GUI_ALV_GRID?", "Why check IS INITIAL in PBO?", "Custom vs docking container?"
Strong answer: screen with custom control, CL_GUI_CUSTOM_CONTAINER with container_name, CL_GUI_ALV_GRID with i_parent, LVC field catalog (LVC_FIELDCATALOG_MERGE) and layout, set_table_for_first_display once, refresh_table_display for updates; create objects only once in PBO; docking container needs no screen element.