18 more AL/BC patterns: data-modeling, testing, style, security, error-handling, ui, upgrade, web-services, appsource

[Michael Dieringer (MichaelDieringer)]

Summary

Second batch from CURABIS ApS — 18 more knowledge articles generalized from patterns observed across real AppSource/PTE Business Central development, follow-up to #156. Same format (6-key frontmatter, Description/Best Practice/Anti Pattern, sibling .good.al/.bad.al samples where a code contrast helps, no fenced code in the .md), targeted at existing Microsoft-owned domains rather than /community/.

• data-modeling (3): WorkDate must never be assigned in app code, Media/MediaSet over BLOB for pictures, the nine BC table-type design conventions (Master/Supplemental/Subsidiary/Ledger/Register/Journal/Document/Document History/Setup).
• testing (5): app-specific BCPT scenarios instead of generic samples, FEATURE/SCENARIO/GIVEN/WHEN/THEN tagging, _UT suffix for UI-layer test codeunits, GIVEN-block precondition completeness for posting/report scenarios, one WHEN per test (with flow-test and defect-then-fix exceptions).
• style (3): pages must not contain business logic, organize source by feature not object type, comments must not restate what the code already shows.
• security (1): every exposed object (API/web-service) must sit in a permission set.
• error-handling (2): log writes must survive rollback via an isolated session, defensive vs. offensive code should match actual blast radius.
• ui (1): the BC page-type design taxonomy (RoleCenter/Card/List/Worksheet/Document/etc.).
• upgrade (1): upgrade-tag guard logic must not nest deeply.
• web-services (1): give API pages least-privilege write access — a separate minimal page per writable field rather than widening a general-purpose one.
• appsource (1): app version bumps should be a deliberate major/minor decision, not left to automatic build/revision increments.

Checked against the current microsoft/knowledge/ corpus before opening — four originally-drafted articles were dropped as duplicates or substantial overlaps of existing files (xrec-is-a-before-image-only-in-some-triggers.md, use-library-codeunits-for-test-fixtures.md + asserterror-needs-expectederror-and-code.md, choose-telemetry-scope-by-audience.md, compose-permission-sets-with-included-sets.md).

Test plan

• CI frontmatter/format validation passes
• Domain-owning reviewers confirm placement and accuracy per file

🤖 Generated with Claude Code

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