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A modal page does not behave like Confirm/StrMenu inside a write transaction: the platform refuses Page.RunModal (and Report/XmlPort .RunModal with a request page, and Codeunit.Run with its return value used) with a runtime error instead of holding the lock. The new article documents that guard - verified against Microsoft Learn (Codeunit.Run transaction semantics), microsoft/AL#5452, Microsoft's own Base Application (Commit(); Page.RunModal pattern), and a live reproduction on Business Central 26 quoted verbatim. avoid-user-prompts-inside- transactions.md keeps its scope to the prompts the platform does allow; "modal page" is removed from its list because that case is refused, not stalled. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
26 lines
1.5 KiB
Markdown
26 lines
1.5 KiB
Markdown
---
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bc-version: [all]
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domain: performance
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keywords: [confirm, strmenu, dialog, transaction, lock, user-interaction]
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technologies: [al]
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countries: [w1]
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application-area: [all]
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---
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# Do not hold locks while waiting for the user
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## Description
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A `Confirm`, `StrMenu`, or other user prompt issued from inside a write transaction stalls the transaction — and therefore every lock it holds — until the user responds. Per the upstream guidance, "Avoid user interactions (Confirm, StrMenu) inside transactions — they hold locks while waiting for user input." The wait is bounded only by the user; meanwhile other sessions block on whatever this transaction has acquired.
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## Best Practice
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Sequence the operation so user confirmation happens *before* any database write that takes a lock the prompt holds open. The shape is: ask the user → if confirmed, acquire locks and post. `if Confirm(...) then begin SalesHeader.LockTable(); SalesHeader.Get(DocNo); PostSalesOrder(SalesHeader); end;` keeps the lock window down to the work itself.
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See sample: [`avoid-user-prompts-inside-transactions.good.al`](avoid-user-prompts-inside-transactions.good.al).
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## Anti Pattern
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`SalesHeader.LockTable(); SalesHeader.Get(DocNo); if Confirm('Post this order?') then ...;` — the lock is held for as long as the dialog is up. A user who steps away to lunch holds the lock for an hour, and every other session that touches that row blocks for the duration.
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See sample: [`avoid-user-prompts-inside-transactions.bad.al`](avoid-user-prompts-inside-transactions.bad.al).
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