fix: write, describe and alter a date picker's DateFormat (#968)

[ako]

Closes #968. Same bug as mendixlabs#1263.

What was wrong

datepicker d (…, DateFormat: Time) and DateFormat: Custom, CustomDateFormat: '…' passed check and were stored as FormattingInfo{DateFormat: Date, CustomDateFormat: ''}. There were three drops: the builder never read the properties, the writer hard-coded newFormattingInfo(), and describe never printed them. check said nothing because validateStaticWidgetUnknownProps skipped the dynamic-text format keys on every widget type, not just dynamictext.

Measured first

• Studio Pro-authored pickers: TestApp WorkflowCommons.WorkflowEndedUserTask and Snip_Workflow_Detail store DateFormat: DateTime plus a leftover CustomDateFormat ('dd/MM/yyyh, HH:mm'). Studio Pro keeps the pattern when you switch the format away from Custom.
• mxbuild (mx check, 11.13, PedApp scratch copy) for each value:
  • Date, Time, DateTime, Custom+pattern, and DateTime+pattern: no errors.
  • Custom with an empty pattern: CE0493 "Date format is custom but no format string is specified."
• Text box: it binds no DateTime attributes (CE2421, MDL-WIDGET39), so only its numeric formatting means anything.

Changes

• Syntax: pages.DatePicker.FormattingInfo replaces a DateFormat string that nothing read. sdk/pages/formatting.go holds the canonical DateFormat values and the per-widget property list, shared by the builder and the mutator.

• Spelling (additive, ADR-0011): the PascalCase widget-property form of the existing format (dateFormat:, customDateFormat:) keys:

  • date picker: DateFormat, CustomDateFormat
  • text box: DecimalPrecision, GroupDigits

• Builder and check: mdl/executor/input_formatting.go uses one validator for both the builder and the check, reported as MDL-WIDGET18. It refuses:

  • an unknown DateFormat
  • a CustomDateFormat with no DateFormat (it would never apply)
  • Custom with no pattern (CE0493)
  • a negative precision, or a non-bool GroupDigits

  A pattern beside an explicit non-Custom DateFormat is accepted, because Studio Pro stores that combination.

• Writer: formattingInfoToGen(x.FormattingInfo) for both DatePicker and TextBox. A nil value is byte-identical to before.

• Describe: prints only non-default values. A leftover pattern is printed together with its DateFormat, so describe's output passes check.

• alter page … set: DateFormat / CustomDateFormat / DecimalPrecision / GroupDigits work through setWidgetFormattingMut. It refuses an invalid value, Custom with no pattern, and a key on the wrong widget type.

• MDL-WIDGET07: the format-key exemption is now per type. DateFormat: on a textarea or text box now warns instead of passing silently.

• Dynamic-text parameter format (…): customDateFormat beside an explicit dateFormat: DateTime is no longer refused. Before this, check on describe's own output for TestApp's Snip_Workflow_CommentsAndAttachments failed with MDL-WIDGET18.

• MCP backend: inputWidget now sends an authored formattingInfo, in the same shape the template parameters use. Not verified against a live Studio Pro MCP.

• Docs: syntax help (features_page.go), create-page skill widgets.md, MDL_QUICK_REFERENCE.md, CHANGELOG, and a finding in mdl-executor.jsonl.

Format-property audit

• Text box DecimalPrecision/GroupDigits: had the same drop; fixed here.
• Dynamic text: per-parameter format (…) already round-tripped; the false refusal is fixed here.
• Reference selector: has a FormattingInfo, but MDL has no builder or writer for it, so there is nothing to drop. Not covered.
• Legacy grid column: has a FormattingInfo; not authorable from MDL.

Test plan

• go test ./mdl/executor/ ./mdl/backend/... ./sdk/pages/ ./cmd/mxcli/ ./mdl/visitor/: pass.
• New tests:
  • mdl/backend/modelsdk/widget_formatting_write_test.go: BSON layer, with a defaults control.
  • mdl/executor/input_formatting_pedapp_test.go: on PedApp, exec → stored unit FormattingInfo per widget → describe prints the values → re-exec the describe output writes no file (GetPut) → control: an edited description is written. Plus alter set, and each refusal leaves the page unchanged.
  • mdl/executor/input_formatting_test.go: check, via ValidateWidgetProperties on parsed MDL.
  • dynamictext_format_test.go: the leftover-pattern case.
• TestApp harness (-tags integration): with WorkflowEndedUserTask and Snip_Workflow_Detail removed from the allowlist, their GetPut diff no longer contains any FormattingInfo/DateFormat path. The date-time pickers keep DateTime and their pattern. Both still break GetPut on unrelated losses (see follow-ups), so their allowlist entries stay. TestTestAppRoundTrip subtests for the four affected documents pass.
• mx check evidence: the probe page on a PedApp copy (Date/Time/DateTime/Custom/leftover-pattern pickers and a text box with precision 4 and grouping) shows no errors for these widgets except CE0493 on the deliberate Custom+empty picker. That picker is what drove the refusal.
• Revert checks: each of these was reverted on its own, and the named test failed with the reported symptom:
  • writer datepicker → DateFormat = Date, want Time
  • writer textbox → 2/false, want 4/true
  • builder → stored Date
  • describe → describe should print DateFormat: Time
  • validateInputFormatting call → no MDL-WIDGET18
  • WIDGET07 per-type exemption → no warning on textarea/textbox
  • param leftover-pattern relaxation → MDL-WIDGET18 on describe-shaped input
  • mutator case → alter set error
• make build, make check-conformance, make lint, make check-findings, make check-mdl, make check-skill-mdl, make sync-skills: pass.

Follow-ups (not in this PR)

• Input-widget ReadOnlyStyle is a silent drop on textbox, textarea and datepicker. The writer hard-codes Inherit, and describe and the builder ignore it (checkbox and dataview already handle it). This is now the only remaining loss on the TestApp date-picker pages, along with textarea NumberOfLines/Autocomplete and a button's OutputMappings on Snip_Workflow_Detail. Until it is fixed, a Studio Pro date-time picker's unit does not yet pass GetPut end to end; its format does.
• The dynamic-text customDateFormat describe does not escape ' (formatParamFormatSuffix writes '+cdf+'). A Java date pattern with literal text ('at') would not round-trip.
• alter page … set (CustomDateFormat: '') on a Custom picker is not refused. Only the DateFormat side checks CE0493, because properties are applied one at a time.

🤖 Generated with Claude Code