fix(writer): ComboBox BSON serialization causes CE1613 — enum written as association, missing EntityRef

[engalar]

Summary

buildComboBoxV3() produces incorrect BSON for both enumeration-mode and association-mode combo boxes, causing CE1613 errors ("The selected association/attribute no longer exists") when the page is opened in Studio Pro or validated with mx check.

Reproduction

Affected pages in GenAIDemo baseline (MyFirstModule):

Page	Widget	Error	Count
P_ComboBox_Enum	cmbPriority	"association 'MyFirstModule.Priority' no longer exists"	1
P_ComboBox_Assoc	cmbCategory	"attribute of combo box 'cmbCategory'"	7

Root Cause

Bug 1: Enum mode — optionsSourceType not reset to "enumeration"

File: mdl/executor/cmd_pages_builder_v3_pluggable.go:91-99

In enum mode (no DataSource), the builder sets attributeEnumeration but never explicitly sets optionsSourceType. It relies on the template default ("enumeration"), which works for fresh templates. However, the BSON in the MPR shows optionsSourceType = "association", causing Mendix to interpret the enum attribute Priority as an association lookup.

Fix: Explicitly set optionsSourceType to "enumeration" in the else branch.

Bug 2: Association mode — EntityRef remains null

File: mdl/executor/cmd_pages_builder_input.go:179-201

For P_ComboBox_Assoc, the attributeAssociation property value shows:

AttributeRef.Attribute = "MyFirstModule.Task.Task_Category"
EntityRef = null

A correct association-mode combo box requires EntityRef = IndirectEntityRef with EntityRefStep containing the Association path and DestinationEntity. The setAssociationRef() function targets the EntityRef key but the resulting BSON still has EntityRef: null, suggesting the template structure or key matching isn't working as expected.

Additionally, the test MDL uses CaptionAttribute: Task_Category (an association name) instead of an attribute on the target entity (e.g., Name), which compounds the error.

Expected BSON (association mode)

attributeAssociation:
  EntityRef: IndirectEntityRef
    Steps:
      - EntityRefStep
          Association: "MyFirstModule.Task_Category"
          DestinationEntity: "MyFirstModule.Category"
  AttributeRef: null

References

• Builder code: mdl/executor/cmd_pages_builder_v3_pluggable.go:31-122
• Association ref setter: mdl/executor/cmd_pages_builder_input.go:179-201
• Attribute ref setter: mdl/executor/cmd_pages_builder_input.go:206-225
• Working roundtrip test: mdl/executor/roundtrip_mxcheck_test.go:742-847 (TestMxCheck_ComboBoxWithAssociation)
• ComboBox template: sdk/widgets/templates/mendix-11.6/combobox.json

[ako]

This works for me, and there are integration tests that validate the generated project with "mx check".

It's TestMxCheck_DoctypeScripts in mdl/executor/roundtrip_doctype_test.go.

How it works:

1. Collects all *.mdl files from mdl-examples/doctype-tests/ (skipping *.test.mdl and *.tests.mdl)
2. For each script, creates a fresh Mendix project (setupTestEnv)
3. Imports required marketplace modules (e.g., ExternalDatabaseConnector, BusinessEvents) via mx module-import
4. Parses and executes the MDL script against the project
5. Disconnects (flushes to disk) and runs mx check to validate
6. Filters known CE errors per script (e.g., CE0161 for XPath, CE0061/CE7056 etc. for REST examples)

It requires the integration build tag: go test -tags integration ./mdl/executor/ -run TestMxCheck_DoctypeScripts

[ako]

Combobox for enumeration, no errors in mendix 11.8.0:

[engalar]

Confirmed

Both bugs are reproducible on the current main branch:

[error] [CE0463] at Combo box 'cmbPriority'   # enum mode
[error] [CE0463] at Combo box 'cmbCompany'     # association mode

Tested by creating ComboBox pages with mxcli exec and running mx check against Mendix 11.6.4.

Resolution

PR #28 (feat/custom-widget-refactor) completely replaces buildComboBoxV3() with a data-driven PluggableWidgetEngine. The code review for that PR already identified and fixed both ComboBox bugs:

1. Association mode source field — changed from "Attribute" to "Association" in combobox.def.json (review round 2, commit 60243b9)
2. Enum mode — the new engine uses widget definitions that handle optionsSourceType correctly per mode

This issue will be resolved when PR #28 is merged. No separate fix needed on main since the old buildComboBoxV3() code is being entirely replaced.

[ako]

Investigation Summary

Reviewed the current main codebase against both bugs described in this issue.

Bug 1 (enum mode): Already fixed

The current buildComboBoxV3() relies on the template default optionsSourceType = "enumeration" (verified in combobox.json). Since enum mode doesn't modify optionsSourceType, the template default is preserved correctly. The enum attribute is set via setAttributeRef() on attributeEnumeration. This works on 11.8.0 per the maintainer's testing.

Bug 2 (association mode): Already fixed

The current code explicitly:

1. Sets optionsSourceType to "association" (line 52-54)
2. Sets attributeAssociation EntityRef via setAssociationRef() with IndirectEntityRef + EntityRefStep (line 67-69)
3. Sets the data source and caption attribute

CE0463 on 11.6.4

The contributor's CE0463 errors on Mendix 11.6.4 may be a template version mismatch — the template was extracted from Mendix 11.6.0, and minor property schema changes between 11.6.0 and 11.6.4 could trigger CE0463 ("widget definition changed"). The maintainer doesn't see this on 11.8.0.

Recommendation

The original bugs appear fixed in current main. The CE0463 issue on 11.6.x is likely template-version-specific and will be resolved by PR #28's data-driven widget engine, which supports per-version widget definitions. No separate fix needed on main.

[ako]

Resolved

PR #28 has been merged, replacing buildComboBoxV3() entirely with the data-driven PluggableWidgetEngine. Both bugs are fixed:

1. Enum mode — optionsSourceType defaults correctly from the template ("enumeration"); only overridden in association mode
2. Association mode — combobox.def.json uses "source": "Association" (fixed in review round 2), correctly populating EntityRef via IndirectEntityRef

The follow-up PR #48 also reverted the Gallery template to the 11.6.0 baseline to fix CI CE0463 failures, and added documentation on the version handling strategy (baseline + MPK augmentation).

Closing this issue.