User Exits Part 4: MV45AFZZ — Sales Order Exits and Save Logic

📌 KEY POINTS
✅ USEREXIT_MOVE_FIELD_TO_VBAK / _VBAP / _VBKD: fill (custom) fields while the user enters data.
✅ USEREXIT_SAVE_DOCUMENT_PREPARE: last point to check and change the document before saving; error messages here stop the save.
✅ USEREXIT_SAVE_DOCUMENT: SAP is saving; use it to write own tables (in update task) — no more changes to the order here.
⚠️ Changing XVBAP in SAVE_DOCUMENT_PREPARE requires setting UPDKZ = 'U' for existing items, otherwise the change is not saved.

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▶ WHERE WE ARE
Part 3 found the exits. MV45AFZZ is the most used user-exit include in SD — this lesson covers its key FORMs.

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▶ 1. DEFAULTS DURING ENTRY

• USEREXIT_MOVE_FIELD_TO_VBAK — header: set custom field ZZ… or defaults based on customer data.
• USEREXIT_MOVE_FIELD_TO_VBAP — item: runs when an item is created/changed; VBAP is the current item.
• USEREXIT_MOVE_FIELD_TO_VBKD — business data (payment terms, incoterms…).
• Only set a field if it is initial or clearly derived, so user input is not overwritten.

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▶ 2. CUSTOM FIELDS

• Append structure to VBAK/VBAP with ZZ fields (SE11).
• Screen: customer subscreens (tabs "Additional data B") in SAPMV45A screens 8309 (header) / 8459 (item) — code in MV45AFZZ/MV45AFZB or the screen PBO/PAI.
• Copy control: data transfer routines if values must be copied from quotation to order.

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▶ 3. CHECKS BEFORE SAVE
USEREXIT_SAVE_DOCUMENT_PREPARE:

• Loop at XVBAP WHERE updkz <> 'D' to check items.
• MESSAGE type E stops saving and returns to the order (dialog). In BAPI calls, the error comes back in RETURN.
• Avoid POPUP functions; the exit runs in background too.

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▶ 4. FINAL CHANGES BEFORE SAVE

• Changing header: modify VBAK and, if needed, VBAK-UPDKZ handling is done by SAP for the header.
• Changing items: modify XVBAP; for existing items set updkz = 'U' if it is initial, then MODIFY xvbap.

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▶ 5. SAVE TIME
USEREXIT_SAVE_DOCUMENT: SAP writes the document; you can write own Z tables via update FM (IN UPDATE TASK) — the order number (VBAK-VBELN) is available here for new orders.

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▶ STEP BY STEP

1. Add a ZZ field via VBAK append (sandbox) and default it in MOVE_FIELD_TO_VBAK.
2. Implement a PO number check in SAVE_DOCUMENT_PREPARE.
3. Write a log table entry in SAVE_DOCUMENT using an update FM.

✅ CHECKPOINT: you use the right MV45AFZZ FORM for defaults, checks, final changes and own tables.

An approval flag set on high-value items in SAVE_DOCUMENT_PREPARE worked for new orders but not for changed orders. The developer had modified XVBAP without setting UPDKZ = 'U' for existing items, so SAP did not update them.
After the fix, the team also noticed that the check message appeared as a hard error in the e-commerce BAPI and was returned correctly in the RETURN table — confirming the exit worked in both paths.

• Changing XVBAP without UPDKZ handling.
• Overwriting user input in MOVE_FIELD exits.
• Popups or COMMIT in save exits.
• Checking deleted items (UPDKZ = 'D').
• Changing the order in USEREXIT_SAVE_DOCUMENT (too late).

• Defaults in MOVE_FIELD exits only when initial.
• Checks and final changes in SAVE_DOCUMENT_PREPARE.
• Own tables via update task in SAVE_DOCUMENT.
• Respect UPDKZ and T180-TRTYP.
• Keep code in Z includes/classes; document each use.

Questions: "Which MV45AFZZ exit do you use for a check before save?", "How do you add a custom field to the sales order?", "Why is my XVBAP change not saved?"
Strong answer: MOVE_FIELD_TO_VBAK/VBAP/VBKD for defaults; SAVE_DOCUMENT_PREPARE for checks (MESSAGE E) and final changes; SAVE_DOCUMENT for own tables via update task; custom fields via VBAK/VBAP append + customer subscreen; XVBAP changes need UPDKZ 'U' for existing items; skip deleted items and display mode.