feat: WidgetDemo baseline

[engalar]

on #68

[ako]

Review

This PR adds one commit on top of #68: MDL baseline scripts for a WidgetDemo module (5 files, ~717 lines of new content). All issues from PRs #66/#67/#68 carry forward.

What's new in this commit

File	Lines	Purpose
01-domain-model.mdl	53	3 enums, 2 entities, 1 association, security grant
01b-snippet.mdl	6	Button showcase snippet
02-showcase-page.mdl	456	95-widget showcase page
03-seed-and-navigate.mdl	98	Seed microflow + navigation grant
WIDGET_ANALYSIS.md	104	Widget classification document

Overall impression

The MDL scripts are well-structured and serve as a comprehensive integration test for the widget engine. The showcase page exercises 62 native and 33 pluggable widgets across 8 sections, which is good coverage. The scripts are self-contained (no external module dependencies).

Issues

1. Does this actually work?

The test plan checkbox "Studio Pro opens project without crash" is unchecked in PR #66 (which this stacks on), and this PR has no test plan at all. A 95-widget showcase page that depends on unreleased features from PRs #66-#68 needs validation. Has mxcli check been run against these scripts? Has the resulting project been opened in Studio Pro?

2. WIDGET_ANALYSIS.md documents known bugs without fixing them

The analysis identifies 2 "misclassified" widgets (BadgeButton, Fieldset) that DESCRIBE renders with native-style names instead of PLUGGABLEWIDGET syntax:

This is a DESCRIBE bug — the widget type mapping in customWidgetTypeShortNames produces a native-looking name.

This should be filed as an issue or fixed, not documented as known-broken in a committed analysis file.

3. Hardcoded placeholder URLs in seed data

ImageUrl = 'https://placehold.co/200x200?text=Headphones'

The seed microflow hardcodes placehold.co URLs. These are external dependencies that will break if the service goes down. For demo/test data this is probably acceptable, but worth noting — if these scripts are used in CI, the images will be broken in an air-gapped environment.

4. LanguageSelector datasource looks wrong

PLUGGABLEWIDGET '...languageselector.LanguageSelector' langSel1 (
  DataSource: DATABASE FROM WidgetDemo.DemoItem,
  languageCaption: '''en_US'''
)

A LanguageSelector backed by DemoItem entities seems semantically wrong — this widget is meant for selecting application languages, not arbitrary entities. This will likely produce a working but nonsensical widget at runtime.

5. Seed microflow uses SHOW PAGE with entity parameter

SHOW PAGE WidgetDemo.WidgetDemo_Showcase(DemoItem: $Existing);

After RETRIEVE ... LIMIT 1, if multiple items exist, only the first is passed. The page's Gallery uses a database datasource anyway (not the parameter), so the DemoItem parameter seems unnecessary for the gallery section. This works but may confuse readers about the page's data flow.

6. File naming convention

01b-snippet.mdl breaks the numeric sequence convention established by 01, 02, 03. Consider 01-domain-model.mdl, 02-snippet.mdl, 03-showcase-page.mdl, 04-seed-and-navigate.mdl — or document why the snippet must be created between domain model and page (if there's an ordering dependency).

Minor observations

• The triple-quoted strings ('''en_US''', '''https://...''') are correct MDL escaping for strings containing single quotes — good
• GRANT EXECUTE ON MICROFLOW and GRANT VIEW ON PAGE are properly placed after their respective CREATE statements
• The showcase page exercises most of the new PLUGGABLEWIDGET syntax features: explicit properties, child widget slots, DataSource, TextTemplate {Param} binding, mode switching (customVisualization: true/false on Timeline)
• WIDGET_ANALYSIS.md is useful for understanding coverage but reads more like a working document than permanent documentation — consider whether it belongs in the repo or in a PR description

Recommendation

This commit is reasonable on its own — it's focused (example scripts + analysis doc) and well-organized. However, it can't be reviewed or merged independently because it depends on the unreleased PLUGGABLEWIDGET syntax from PR #68, which in turn depends on #67 and #66. The entire 4-PR stack needs to be reviewed as a unit, which at 51K+ lines is not practical.

Suggest: resolve the issues in #66 first, then rebase the stack. Each PR should be independently mergeable.

[engalar]

Review Response

Rebased on updated feat/widget-engine-v2 (which is now rebased on latest main). Changes in commit 0b0c1c0.

Fixed

#	Issue	Fix
2	WIDGET_ANALYSIS.md committed	Removed — working document, not permanent docs
4	LanguageSelector with DemoItem datasource	Removed nonsensical datasource and languageCaption — widget now uses defaults
6	File naming 01b-snippet.mdl breaks convention	Renumbered: 01b→02, 02→03, 03→04

Evaluated but not changed

Item	Reason
Placeholder URLs (placehold.co)	Acceptable for demo scripts — these are example MDL, not CI fixtures. Added no external dependency to the build.
SHOW PAGE with DemoItem parameter	The page's DataView uses DataSource: $DemoItem (line 118 in showcase page), so the parameter is required. The Gallery uses its own DATABASE datasource independently.
Validation (mxcli check / Studio Pro)	Depends on PR #68 being merged first — will validate post-merge.

[github-actions]

AI Code Review

Critical Issues

• Incorrect string literal syntax in videoplayer property: In mdl-examples/widgetdemo/03-showcase-page.mdl, the urlExpression property for the Videoplayer widget uses triple single quotes ('''...''') instead of proper single quotes. According to Mendix expression string escaping rules (as documented in CLAUDE.md), string literals should be enclosed in single quotes, with internal single quotes escaped by doubling them. Since the URL contains no single quotes requiring escaping, it should be: urlExpression: 'https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4'. The current triple-quote syntax is invalid and would cause parsing errors.

What Looks Good

• Proper MDL syntax usage: All examples correctly follow MDL design guidelines:
  • Use standard CRUD verbs (CREATE, GRANT)
  • Employ qualified names everywhere (WidgetDemo.Module.Element)
  • Follow property format ( Key: value, ... ) with colon separators
  • Correctly distinguish colon (for properties) from AS (for name mappings - though none appear in these examples)
  • Use full English keywords with no overloading
    precated

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