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* Add runmodal-is-not-allowed-inside-write-transactions.md; drop "modal page" from the prompts article 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> * Do not list Message among the lock-holding prompts Message runs asynchronously - it is queued and shown when the calling method ends or another method requests input - so it never pauses the transaction and holds no lock. Only Confirm and StrMenu wait for the user. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> * State the four write-transaction conditions as one explicit line per method Mirrors the structure of the platform's own error message so the Report.RunModal and XmlPort.RunModal request-page exceptions are visible at a glance instead of buried in prose. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> * Title the article after the platform error it explains "AL methods limited during write transactions: commit before RunModal and Codeunit.Run" - so a developer or agent searching for the runtime error text lands on the one article that covers all four restricted methods. Slug and sample stems renamed to match; keywords gain the error's own phrase and the legacy Form.RunModal name it still uses. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> * Trim keywords to 10 per validator guidance * Wire the new article into al-performance-review.md Adds Page.RunModal / Report.RunModal / XmlPort.RunModal / UseRequestPage to the extracted-token list and one deterministic worklist cue with exclusions, so the article is selected from the RunModal call itself rather than only via a co-located Commit/Modify token. Codeunit.Run in that position is routed to its existing owner article. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> * Correct XmlPort.RunModal to Xmlport.Run; fix READ-convention sample links XmlPort has no RunModal method (static or instance) - Microsoft Learn confirms only Xmlport.Run(Integer [, Boolean RequestWindow] [, Boolean] [, var Record]). Replaces the invented API with the real one throughout the article, worklist cue, and token list, and explains the platform error message's own "XmlPort.RunModal" wording as the same kind of legacy phrasing already noted for Form.RunModal/RequestForm. Also corrects UseRequestPage(false): that's a Report instance method only, not applicable to XMLport, which uses the UseRequestPage = false object property or Run's RequestWindow argument instead. Fixes the two sample references to use the READ-convention markdown link form (Test-KnowledgeIndex.ps1's Knowledge-Retrieval.ps1 check was failing on plain backtick text). Rebased onto upstream/main to resolve conflicts with #148's job-queue additions to al-performance-review.md - both sets of worklist tokens and cues are retained. * Add Report.Run alongside Report.RunModal to the write-transaction guard routing al-performance-review.md's tokens/cues only recognized Report.RunModal, so a failing Modify(); Report.Run(..., true, ...) path was never worklisted even though Report.Run shares the exact same RequestWindow- blocking-dialog mechanism as Report.RunModal (they differ only in whether the report instance is cleared afterward). Added Report.Run to the token list and the targeted cue, with the same request-page- suppressed exclusion, and extended the knowledge article's Description bullet to name both methods explicitly instead of only RunModal. --------- Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com> Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com> Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
46 lines
7.8 KiB
Markdown
46 lines
7.8 KiB
Markdown
---
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bc-version: [all]
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domain: performance
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keywords: [limited-during-write-transactions, write-transaction, runmodal, report-run, page-runmodal, report-runmodal, xmlport-run, codeunit-run, commit, requestpage]
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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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# AL methods limited during write transactions: commit before RunModal and Codeunit.Run
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## Description
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Once AL code has written to the database in the current transaction — an `Insert`, `Modify`, or `Delete` with no `Commit` since — the platform restricts four methods until that transaction is committed. The exact conditions, as enforced:
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- `Page.RunModal` — not allowed in a write transaction, under any circumstances.
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- `Report.RunModal` and `Report.Run` — both allowed only if the request page is suppressed: `Report.RunModal(ReportId, false)` / `Report.Run(ReportId, false)` (the second argument is `RequestWindow` in both), or `UseRequestPage(false)` on a report instance. With a request page shown, either fails identically — `Run` and `RunModal` differ only in whether the report instance is cleared afterward, not in this guard.
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- `Xmlport.Run` — same rule when it would show a request page: allowed only if the request page is suppressed, `Xmlport.Run(XmlPortId, false)` (the second argument is `RequestWindow`) or the `UseRequestPage = false;` object property. With a request page shown it fails. There is no `XmlPort.RunModal` method — see the note on the platform's error text below.
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- `Codeunit.Run` — allowed only if its Boolean return value is not used. `OK := Codeunit.Run()` and `if Codeunit.Run() then` fail, because that form commits — see `codeunit-run-requires-prior-commit-inside-transaction.md`.
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This is a runtime error, not a compiler diagnostic: the code builds, and the first execution that reaches the call with an open write transaction dies. The guard keys on transaction state alone, not on any relation between what was written and what is opened: an `Item.Insert()` followed by `Page.RunModal(Page::"Customer Card")` — an unrelated table — fails on the `RunModal` line, and because the error stops the transaction, the insert rolls back with it.
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The platform's message (Business Central 26, reproduced 2026-09-07) reads: "The following AL methods are limited during write transactions because one or more tables will be locked: Form.RunModal, Codeunit.Run, Report.RunModal, XmlPort.RunModal. Form.RunModal is not allowed in write transactions. Codeunit.Run is allowed in write transactions only if the return value is not used. For example, 'OK := Codeunit.Run()' is not allowed. Report.RunModal is allowed in write transactions only if 'RequestForm = false'. For example, 'Report.RunModal(...,false)' is allowed. XmlPort.RunModal is allowed in write transactions only if 'RequestForm = false'. For example, 'XmlPort.RunModal(...,false)' is allowed. Use the commit method to save the changes before this call, or structure the code differently." The message still uses the legacy names `Form.RunModal` and `RequestForm` even though the AL method is `Page.RunModal` and the report parameter is `RequestWindow`; older versions said "C/AL functions" instead of "AL methods" (microsoft/AL#5452, 2019). The message also names `XmlPort.RunModal`, which is legacy phrasing too — there is no such AL method; the actual API the guard applies to is `Xmlport.Run`, and the message's `RequestForm = false` condition corresponds to `Xmlport.Run`'s `RequestWindow` argument or the `UseRequestPage` property. The behavior is unchanged across versions.
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The reason is the same one behind `avoid-user-prompts-inside-transactions.md`: a modal object waits for the user, and the platform will not let a write transaction — and every lock it holds — sit open for as long as that takes. The difference is enforcement. `Confirm` and `StrMenu` are *allowed* inside a write transaction and silently hold the locks; `RunModal` is *refused*. Both point at the same design fix.
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## Best Practice
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Sequence the work so the modal interaction happens before the write phase: run the lookup or dialog page first, then perform the writes the user's choice requires, and let the transaction end. When a modal object genuinely must follow a write, `Commit()` first — but only when the state written so far is complete and safe to persist on its own, because that Commit is a real transaction boundary, not a formality. Microsoft's own Base Application follows exactly this pattern where the preceding state is final (`ActivityLog.Table.al` commits the log entry before `Page.RunModal(Page::"Activity Log", Rec)`; `DocumentSendingProfile.Table.al` commits before `Page.RunModal(Page::"Select Sending Options", …)`). For a report, suppressing the request page — `Report.UseRequestPage(false)` on a report instance, or `false` as the `RequestWindow` argument to `Run`/`RunModal` — is a legitimate way to run it inside a write transaction when no user input is needed. For an XMLport, the equivalent is `false` as the `RequestWindow` argument to `Xmlport.Run`, or the `UseRequestPage = false;` object property; XMLports have no instance `UseRequestPage` method. `Database.IsInWriteTransaction()` (runtime 11.0+) lets library code that cannot control its caller detect the state, with the same caveat as the Codeunit.Run article: branching production flow on it usually signals unclear transaction ownership.
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See sample: [`al-methods-limited-during-write-transactions.good.al`](al-methods-limited-during-write-transactions.good.al).
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## Anti Pattern
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Writing to the database and then calling `Page.RunModal` (or a report/XMLport with its request page) in the same trigger — the first production run hits the runtime error. The reflexive fixes are worse than the error: dropping in `Commit()` to silence it persists a half-finished state that can no longer roll back with the rest of the operation, and swapping the page for a `Confirm` or `StrMenu` to "avoid the error" trades a loud failure for the silent lock-holding that `avoid-user-prompts-inside-transactions.md` warns about.
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See sample: [`al-methods-limited-during-write-transactions.bad.al`](al-methods-limited-during-write-transactions.bad.al).
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## Source
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- Microsoft Learn, `Codeunit.Run` transaction semantics ("If you're already in a transaction you must commit first before calling Codeunit.Run"): https://learn.microsoft.com/dynamics365/business-central/dev-itpro/developer/methods-auto/codeunit/codeunit-run-method
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- Microsoft Learn, `Xmlport.Run(Integer [, Boolean] [, Boolean] [, var Record])` (the `RequestWindow` argument; confirms the XMLport data type has no `RunModal` method, static or instance): https://learn.microsoft.com/dynamics365/business-central/dev-itpro/developer/methods-auto/xmlport/xmlport-run-method
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- Microsoft Learn, `UseRequestPage` property ("Applies to: Xml Port, Report" — an object property, not an XMLport instance method; the instance method of the same name exists only on `Report`): https://learn.microsoft.com/dynamics365/business-central/dev-itpro/developer/properties/devenv-userequestpage-property
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- microsoft/AL issue #5452 (verbatim English error text, reproduced on "any current version of Business Central", 2019-11-13): https://github.com/microsoft/AL/issues/5452
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- Reproduced 2026-09-07 on Business Central 26 (runtime error dialog, English and Danish clients): a page `OnAction` doing `Item.Insert()` then `Page.RunModal(Page::"Customer Card")` fails with the text quoted in the Description, the AL call stack pointing at the `RunModal` line, and the dialog stating that the transaction was stopped.
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- Microsoft Base Application (BCApps, W1): the `Commit(); … Page.RunModal(…)` pattern in `Modules/System/Logging/ActivityLog.Table.al`, `Foundation/Reporting/DocumentSendingProfile.Table.al`, `Bank/Setup/PaymentServiceSetup.Table.al`, and others; BCApps test suites annotate the same guard as "COMMIT is required for Write Transaction Error" (`Tests/General Journal/ERMTestMultipleGenJnlLines.Codeunit.al`).
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