Microsoft/bcquality
1
0
Fork 0
mirror of https://github.com/microsoft/BCQuality.git synced 2026-08-06 17:36:53 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions
bcquality/microsoft/knowledge/data-modeling/table-relation-extensions-are-additive-and-top-down.md
Jesper Schulz-Wedde e81632b4be Complete AL review knowledge readiness 
Fill telemetry and Query coverage, strengthen thin review domains, correct audited content defects, and add deterministic cheap-model evaluation and reference-integrity safeguards.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 9825b012-e653-496a-9310-c1f4b6f8ac27
2026-07-15 07:19:15 +02:00

1.6 KiB
Raw Blame History

bc-version domain keywords technologies countries application-area
all
data-modeling
tablerelation
tableextension
enumextension
additive
top-down
unconditional-relation
al
w1
all

Design TableRelation branches for additive top-down extension

Description

A tableextension can add to an existing TableRelation, but the combined relation is evaluated top-down after the original value. The first unconditional relation wins. An extension branch appended after an unconditional base relation is therefore unreachable, even though the extension compiles and appears to describe the new enum value correctly.

Best Practice

When a relation is designed to follow an extensible enum, express the base cases as conditional branches and leave no unconditional catch-all ahead of future extension branches. An enum extension can then append a condition for its new value. When extending a field you do not own, inspect the original TableRelation; do not claim that an appended condition overrides an unconditional relation.

See sample: table-relation-extensions-are-additive-and-top-down.good.al.

Anti Pattern

A base field has an unconditional TableRelation = Customer; and a tableextension adds if (Type = const(Resource)) Resource. The original unconditional branch always wins, so the new enum value still validates and looks up against Customer. The concern is evaluation order, not ValidateTableRelation; free-form input is covered separately by security guidance.

See sample: table-relation-extensions-are-additive-and-top-down.bad.al.