18 AL/BC patterns: style, data-modeling, web-services, appsource, breaking-changes, performance, testing

[Michael Dieringer (MichaelDieringer)]

Summary

18 knowledge articles generalized from patterns observed across real AppSource/PTE Business Central development, contributed by CURABIS ApS. Each is a self-contained article following the knowledge file format (6-key frontmatter, Description/Best Practice/Anti Pattern, sibling .good.al/.bad.al samples, no fenced code in the .md).

Targeted at existing Microsoft-owned domains per the README's contribution guidance ("use /microsoft/knowledge/ for Microsoft-owned domains") rather than /community/, since these all fall under domains BCQuality already owns action skills for.

• style (7): AL identifier/casing/typing conventions — Boolean vs Option for binary choices, Enum vs Integer for fixed choice sets, modern casing for intrinsic functions, addressable var parameters, namespace verification, English-only identifiers, keeping build output out of the project root.
• data-modeling (4): DimensionManagement wiring for new master/document tables, the Check Line / Post Line / Post Batch posting-routine split, primary key immutability post-publish, TestField-before-use for required setup fields.
• web-services (3): CalcFields for FlowFields on API pages, keeping consumer-provided key fields editable on insert, recalculating stored/derived fields before exposing them via API.
• appsource (1): File data type direct I/O is OnPrem-only.
• breaking-changes (1): Prefer the Email module over the obsolete Codeunit 397 "Mail".
• performance (1): Document reports should default to Word layout.
• testing (1): Randomized, complete test data via library helpers.

Checked against the current microsoft/knowledge/ corpus before opening this PR (post the recent community→microsoft consolidation) — two originally-drafted articles were dropped as duplicates 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).

Test plan

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

🤖 Generated with Claude Code

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