bcquality/microsoft/knowledge/security/do-not-disable-validatetablerelation-on-user-input.md
Jesper Schulz-Wedde e570d6113f Extract 55 knowledge articles from BC review-agent prompt
Adds 55 articles (plus 76 code samples) spanning four new domains and
two existing domains, extracted from the internal Business Central
review-agent prompt. Content was filtered against BCQuality's
remedial-knowledge premise: each article encodes BC-specific behaviour,
a CodeCop rule, a platform API semantic, or an anti-false-positive
guideline that a capable LLM would otherwise get wrong.

New domains:
- privacy (11 articles): DataClassification inheritance semantics, the
  StrSubstNo-defeats-Error-telemetry-classification pitfall, Privacy
  Notice consent for outgoing requests, anti-false-positives for pages
  and in-memory data.
- upgrade (11 articles): upgrade-codeunit structure, upgrade-tag
  lifecycle and registration, protected DB reads, DataTransfer for
  large datasets, InitValue semantics, enum-ordinal preservation,
  obsolete-workflow, first-install detection.
- ui (9 articles): caption capitalization by phrase type, tooltip voice,
  teaching-tip vs tooltip, tour-tip conventions, character limits,
  banned terms, ampersand handling, title punctuation.
- style (11 articles): label-suffix convention, API page naming,
  temporary-variable prefix, label properties (Comment/Locked), named
  invocations, FieldCaption in user messages, OptionCaption pairing,
  Error-parameter passing, `this` keyword, required parentheses, file
  naming.

Gaps in existing domains:
- performance (11 articles): production-scale table catalog (no row
  counts, per internal-data concern), anti-false-positive for bounded
  tables, guard-before-Get ordering, redundant-Get-in-OnAfterGetRecord,
  LockTable in read-only helpers, combined ModifyAll passes, writes in
  OnAfterGetRecord, SetLoadFields heuristics, temporary-table
  regressions, FlowField source-table widening, MaintainSQLIndex
  disabling SIFT.
- security (2 articles): environment-specific hardcoded GUIDs,
  ValidateTableRelation=false on user input.

Intentionally excluded: specific production P95 row-count numbers
(aggregated internal telemetry); rewritten as categorical guidance on
which tables to treat as production-scale without publishing sizes.

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2026-04-23 16:43:42 +02:00

1.9 KiB

bc-version domain keywords technologies countries application-area
all
security
validatetablerelation
user-input
lookup
integrity
validation
al
w1
all

Do not set ValidateTableRelation = false on fields that accept user input

Description

TableRelation on a field tells the platform that the value must exist as a primary key in the related table. ValidateTableRelation = false suppresses that check at validation time. On system-populated fields — values the code sets from a controlled source and never displays as editable — the suppression is acceptable because the integrity guarantee comes from the upstream writer. On a field the user types into (a page field, an import column, an API payload), disabling the validation means any value at all can be written: a non-existent customer number, a typo, a deliberate bad value. The table no longer enforces the relation, and downstream code that Gets the related row with an unguarded lookup breaks.

Best Practice

Leave ValidateTableRelation = true (the default) on any field the user can set. When the default would produce unhelpful behaviour — a transient lookup that does not yet exist at validation time, a reference that uses a non-primary-key column — handle it with a targeted OnValidate trigger that performs the semantic check explicitly. Use ValidateTableRelation = false only when the field is genuinely system-controlled and the writer has already validated the reference.

See sample: do-not-disable-validatetablerelation-on-user-input.good.al.

Anti Pattern

A Customer No. field on an editable page with TableRelation = Customer."No." and ValidateTableRelation = false and no OnValidate fallback. The user can type any string; the platform accepts it; a later Get against Customer fails or returns the wrong row.

See sample: do-not-disable-validatetablerelation-on-user-input.bad.al.