bcquality/microsoft/knowledge/data-modeling/dimension-management-wiring.md
Michael Dieringer faa0bceb86 Fix remaining correctness issues from Jesper's 2026-09-15 re-review
- dimension-management-wiring: SaveDefaultDim's third argument is the
  shortcut dimension number (1-8), not the field's AL field ID; the
  fixture passed FieldNo(...) = 10. GetDefaultDimID's InheritFromDimSetID
  must be 0 when recomputing after the linking record changes, not the
  document's existing Dimension Set ID (which would retain the previous
  customer's leftover dimensions). Verified against
  DimensionManagement.Codeunit.al and BankDepositHeader.Table.al in the
  BCApps reference clone.
- check-post-line-batch-pattern: "Post Line writes exactly one line to
  the ledger" overclaimed - Gen. Jnl.-Post Line alone calls InsertGLEntry
  from a dozen call sites (balancing entry, VAT, currency rounding,
  deferrals) and can write several G/L Entries per journal line.
  Reworded to "posts exactly one journal line" and softened the
  "distinct, non-overlapping responsibilities" absolute.
- namespace-must-be-verified-from-source.bad.al: dropped the "resolves
  in a local build, fails in VS Code" comment (taught an inherent
  compiler/language-server disagreement that isn't real); reframed as
  stale/cached symbols, matching the prose fix already made.
- file-datatype-saas.good.al: replaced the deprecated 5-argument
  UploadIntoStream overload with the current 2-argument one, and
  actually staged through TempBlob as the article's own Best Practice
  instructs (the declared TempBlob variable was previously unused).
- test-data-must-be-random-and-complete: no longer treats a
  short-but-valid value as defective merely for being "underfilled" -
  AL field lengths are maxima, not minimums. Scoped to missing values
  or a scenario with an explicit length/format requirement (e.g. a
  truncation test). Updated the al-testing-review.md routing cue to
  match.
- stored-derived-fields-must-not-be-exposed-directly: stopped mandating
  source-field exposure as part of the core pattern: the good fixture
  exposed only one of the derived value's two inputs (Hours Used, not
  Budgeted Hours), making the claimed "so the consumer can verify it"
  impossible. Reframed as an optional, all-or-nothing addition and
  fixed the fixture to expose both inputs.

Rebased onto upstream/main to resolve conflicts in
al-breaking-changes-review.md, al-data-modeling-review.md,
al-performance-review.md, and al-style-review.md against merged PRs
#148 and #153; all sides' worklist tokens/cues retained.
2026-09-21 22:26:51 +02:00

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3.7 KiB
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---
bc-version: [all]
domain: data-modeling
keywords: [dimensions, dimensionmanagement, global-dimension, shortcut-dimension, default-dimension, validatedimvaluecode, getdefaultdimid]
technologies: [al]
countries: [w1]
application-area: [all]
---
# Wire dimension support through DimensionManagement, not ad hoc fields
> Contributions welcome — open a PR to refine or extend this article.
## Description
Adding dimension support to a custom table is not just a matter of adding a `Code[20]` field, and master tables and document/transactional tables wire into `Codeunit "Dimension Management"` through two different models — treating them as one mechanism is itself the mistake this article corrects:
- **Master data** (a custom master table, e.g. "Course") persists **Default Dimension** records: each shortcut dimension field validates through `ValidateDimValueCode`, then the result is saved via `SaveDefaultDim`, and `DeleteDefaultDim` removes them again in `OnDelete`. Both `ValidateDimValueCode` and `SaveDefaultDim` take the shortcut dimension *number* (1-8, matching `General Ledger Setup`'s "Shortcut Dimension N Code" fields) as their first/third argument respectively — not the AL field ID of the table field being validated. The master record itself carries no `Dimension Set ID` field.
- **Transactional/document data** (a custom document or journal-line table) carries a single **`Dimension Set ID`** field — a pointer to a shared, deduplicated set of dimension values in `Dimension Set Entry`, assembled from whatever the document inherited plus whatever the user overrode. A document does not acquire that ID by calling `SaveDefaultDim`; it builds a source list with `AddDimSource` (naming the related master table and its key, e.g. `Database::Customer`), then calls `GetDefaultDimID` to compute a new `Dimension Set ID` that inherits the master's Default Dimension records. Editing a shortcut dimension field directly on the document validates through `ValidateShortcutDimValues`, which updates the same `Dimension Set ID` in place rather than writing a separate Default Dimension record.
Skipping the model that actually matches the table's kind produces a field that looks correct in the designer but silently fails to save, validate, or carry through to postings — or, for a document, one that never picks up the customer's/vendor's own dimensions at all.
## Best Practice
For a master table, validate each shortcut dimension field through `ValidateDimValueCode`, save the result with `SaveDefaultDim`, and delete the matching Default Dimension records in `OnDelete`.
For a document table, when the field that attaches the document to a master record changes (e.g. `Customer No.`), call `AddDimSource` naming that master table and key, then `GetDefaultDimID` to compute the document's new `Dimension Set ID`, inheriting the master's Default Dimension records. Pass `0` for `GetDefaultDimID`'s `InheritFromDimSetID` argument in this case — passing the document's *existing* `Dimension Set ID` instead inherits whatever dimensions were already in it, so a value the previous linked record supplied can survive into the new one even where the new record has no default for that dimension. Validate the document's own Shortcut Dimension fields through `ValidateShortcutDimValues`, which updates that same `Dimension Set ID` in place rather than persisting a separate Default Dimension record.
See sample: `dimension-management-wiring.good.al`.
## Anti Pattern
Adding a dimension-looking field with only a `TableRelation` to Dimension Value, and no call into `DimensionManagement` at all. The field accepts input but never becomes a real Default Dimension record, so it does not validate against blocked values and does not flow into postings.
See sample: `dimension-management-wiring.bad.al`.