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Six carried-over threads: - api-page-least-privilege-write-access fixtures: added the mandatory EntityName/EntitySetName properties (AL0485). - pages-must-not-contain-business-logic fixtures: Sales Line has no "Total Amount" field; replaced with the real "Line Amount" (field 103). - test-feature-scenario-tags.good.al and test-one-when-per-test.good.al: CreatePriceHeader leaves a price list in Draft status, which price calculation ignores. Added Validate(Status, Active) + Modify before the sales line that depends on it. Verified Status field/enum against PriceListHeader.Table.al and PriceStatus.Enum.al in the BCApps clone. - exposed-objects-must-be-in-a-permission-set.md: a published codeunit is a SOAP endpoint (SOAP is deprecated), not OData - Page/Query are the OData object types. Corrected and pointed new integrations at API pages/queries instead. - al-error-handling-review.md: the log-writes-must-survive-rollback cue selected on Session.StartSession, which only appears in the compliant fix, never in the anti-pattern - the bad fixture could never be worklisted. Recued on the actual risk shape (log insert around a failed TryFunction/GetLastError* path, then raise/propagate), with StartSession as an explicit compliant discriminator instead. - page-design-must-match-bc-page-type-conventions.md: the enum value is NavigatePage, not Navigate; noted the type list is a selected subset, not an exhaustive PageType catalogue (PromptDialog, ConfigurationDialog, UserControlHost, XmlPort also exist, out of this article's scope). Four new correctness gaps: - release-must-update-app-version.md: "the version is the only identity" was backwards - id is the app's stable identity, version identifies a release/code-state of it. - defensive-vs-offensive-code-must-match-blast-radius.good.al: the "low blast radius" example had no else branch, so a failed Customer.Get() left the field at its prior/default value instead of the explicit chosen fallback the article claims to demonstrate. Added the else. - bcpt-scenarios-must-be-app-specific.good.al: InitTest and both measured StartScenario/EndScenario sections were empty/comment-only, so the "app-specific" fixture measured no actual work. Filled in a real, self-contained header+line creation path. - upgrade-tag-logic-must-not-nest-deeply.good.al: the flattened version dropped both safety conditions the bad fixture had (Discount % = 0, nonblank posting group), silently changing behavior instead of just removing nesting. Extracted the guarded update into a helper with both conditions preserved as early exits. Also converted this PR's remaining plain-backtick "See sample:" sample references (16 articles) to the READ-convention markdown-link form, matching the fix already made on #156/#158. Rebased onto upstream/main (conflicts in al-ui-review.md, al-style-review.md, al-upgrade-review.md against merged upstream PRs - all additive, both sides' worklist cues retained).
26 lines
2.4 KiB
Markdown
26 lines
2.4 KiB
Markdown
---
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bc-version: [all]
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domain: error-handling
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keywords: [logging, rollback, session, transaction, isolated-session, telemetry]
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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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# Log writes that must capture failures must survive transaction rollback
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## Description
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Inserting a log record inside the same transaction as the operation it logs looks correct until the operation errors: the transaction rolls back and takes the log entry with it. The result is a log that faithfully records every success and silently loses exactly the failures it exists to capture. This is a common blind spot in error/duration logging around web-service calls, background jobs, and other operations expected to fail sometimes.
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## Best Practice
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Write any log whose purpose includes capturing failures from a transaction that is independent of the operation being logged: start an isolated session (`Session.StartSession` on a `TableNo`-scoped codeunit that only inserts the log record and commits) so the entry persists regardless of what happens to the caller's transaction. `StartSession`'s only channel for getting data into that new session is its optional `Record` parameter, delivered to the target codeunit's `OnRun` trigger — a separate session gets a fresh instantiation of the codeunit, so calling a setter procedure on a local object variable before starting the session does not populate anything in the new session's instance. Capture duration and other telemetry values in the caller, place them into the `Record` passed to `StartSession`, and do the insert-and-commit entirely inside that session's own `OnRun`. Logs that only record successful, committed work can safely stay in the main transaction; this pattern targets error and diagnostic logs specifically.
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See sample: [`log-writes-must-survive-rollback.good.al`](log-writes-must-survive-rollback.good.al).
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## Anti Pattern
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Inserting the error-log record in the same transaction as the risky operation, so a rollback deletes the very entry meant to explain the failure. Adding a stray `Commit` before the risky call is not a fix either — it breaks the caller's atomicity and can violate posting-routine rules. Swallowing the error to keep the log alive (running a codeunit without checking or re-raising its result) is equally wrong: the log must observe the failure, not suppress it.
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See sample: [`log-writes-must-survive-rollback.bad.al`](log-writes-must-survive-rollback.bad.al).
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