fix(widgets): null hidden chart-series textTemplates (TimeSeries markerColor)

A TimeSeries/LineChart with a default 'line' series tripped CE0463: the series'
markerColor textTemplate was serialized as an empty Forms$ClientTemplate, but
Studio Pro stores it as null when the property is hidden. chartSeriesTextTemplateVisible
honored only the dataSet (static/dynamic) gate and missed the item-level editorConfig
gates — markerColor is hidden unless lineStyle == 'lineWithMarkers' (default 'line'),
and fillColor unless enableFillArea is truthy (default true).

Add chartSeriesTextTemplateHiddenByItemConfig, mirroring the widget's
hideNestedPropertiesIn rules, so a hidden series textTemplate serializes as null
rather than an empty ClientTemplate. Verified: default TimeSeries line -> 0 errors,
lineStyle 'lineWithMarkers' keeps markerColor visible, full chart example (all
types) 0 errors.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JXnEgoc2NQP1Y2TWMCMXC4

Author: claude

mdl-examples/bug-tests/timeseries-marker-color-null.mdl

@@ -0,0 +1,45 @@
+-- ============================================================================
+-- Bug: TimeSeries/LineChart series markerColor emitted as empty ClientTemplate
+-- ============================================================================
+--
+-- Symptom:
+--   A TimeSeries (or LineChart) with a default `line` series failed mx check:
+--     [CE0463] "The definition of this widget has changed…" at Time series
+--   The series' `markerColor` textTemplate was serialized as an empty
+--   Forms$ClientTemplate, but Studio Pro stores it as null when markers are off.
+--
+-- Root cause:
+--   A chart-series textTemplate that is VISIBLE serializes as an empty
+--   ClientTemplate; one that is HIDDEN must be null. chartSeriesTextTemplateVisible
+--   honored only the dataSet (static/dynamic) gate — it missed the item-level
+--   editorConfig gates: `markerColor` is hidden unless lineStyle == "lineWithMarkers"
+--   (default "line"), and `fillColor` is hidden unless enableFillArea is truthy.
+--
+-- Fix:
+--   chartSeriesTextTemplateHiddenByItemConfig nulls markerColor / fillColor when the
+--   item's lineStyle / enableFillArea hides them, mirroring the widget's
+--   editorConfig hideNestedPropertiesIn rules.
+--
+-- Verify:
+--   mxcli exec mdl-examples/bug-tests/timeseries-marker-color-null.mdl -p app.mpr
+--   mx check app.mpr    # 0 errors — markerColor null on the default line series
+-- Requires: Charts .mpk installed in the project's widgets/.
+-- ============================================================================
+
+create module TSMarker;
+/
+create entity TSMarker.Sale ( SaleDate: DateTime, Total: Decimal );
+/
+create or replace page TSMarker.Home ( layout: Atlas_Core.Atlas_Default ) {
+  -- default line style: markerColor is hidden -> must be null (not empty ClientTemplate)
+  pluggablewidget 'com.mendix.widget.web.timeseries.TimeSeries' tsPlain {
+    line lRev ( DataSet: 'static', DataSource: database from TSMarker.Sale,
+                StaticXAttribute: SaleDate, StaticYAttribute: Total, StaticName: 'Revenue' )
+  }
+  -- lineWithMarkers: markerColor is visible -> empty ClientTemplate is correct
+  pluggablewidget 'com.mendix.widget.web.timeseries.TimeSeries' tsMarkers {
+    line lRev2 ( DataSet: 'static', lineStyle: 'lineWithMarkers',
+                 DataSource: database from TSMarker.Sale,
+                 StaticXAttribute: SaleDate, StaticYAttribute: Total, StaticName: 'Revenue' )
+  }
+}

mdl/executor/widget_engine.go

@@ -808,6 +808,42 @@ func chartSeriesTextTemplateVisible(ip ItemPropertyMapping, dataSetMode string,
 	return true
 }
 
+// chartSeriesTextTemplateHiddenByItemConfig reports whether a chart-series
+// textTemplate sub-property is hidden by the widget's editorConfig based on OTHER
+// item-level property values (beyond the dataSet gate). These mirror the
+// `hideNestedPropertiesIn` rules in the chart editorConfig.js:
+//
+//	markerColor  visible only when lineStyle == "lineWithMarkers"  (default "line")
+//	fillColor    visible only when enableFillArea is truthy          (default true)
+//
+// Without this, a hidden sub-property's empty-ClientTemplate default (which
+// chartSeriesTextTemplateVisible would otherwise emit) trips CE0463 — e.g.
+// markerColor on a default "line" TimeSeries/LineChart series. Absent keys use the
+// schema default.
+func chartSeriesTextTemplateHiddenByItemConfig(propertyKey string, itemConfig map[string]string) bool {
+	switch propertyKey {
+	case "markerColor":
+		lineStyle := itemConfig["lineStyle"]
+		if lineStyle == "" {
+			lineStyle = "line"
+		}
+		return lineStyle != "lineWithMarkers"
+	case "fillColor":
+		enableFillArea := itemConfig["enableFillArea"]
+		if enableFillArea == "" {
+			enableFillArea = "true" // schema default
+		}
+		return !isTruthyPrimitive(enableFillArea)
+	}
+	return false
+}
+
+// isTruthyPrimitive reports whether a primitive string value is truthy (non-empty,
+// not "false"/"0"). Mirrors the editorConfig's boolean gate semantics.
+func isTruthyPrimitive(v string) bool {
+	return v != "" && v != "false" && v != "0"
+}
+
 // seriesDataSourceMatchesMode reports whether a chart-series datasource property
 // key (staticDataSource / dynamicDataSource) is the one active for the given
 // dataSet mode — used to route the friendly `DataSource:` alias. Chart series (9a).
@@ -846,6 +882,17 @@ func (e *PluggableWidgetEngine) buildObjectListItem(mapping *ObjectListMapping,
 		}
 	}
 
+	// itemConfig holds the user-set item-level values that gate the visibility of
+	// OTHER sub-properties in the widget's editorConfig (chart series: lineStyle
+	// gates markerColor, enableFillArea gates fillColor). Absent keys fall back to
+	// the schema default inside chartSeriesTextTemplateHiddenByItemConfig.
+	itemConfig := map[string]string{}
+	for _, key := range []string{"lineStyle", "enableFillArea"} {
+		if v, ok := lookupProperty(child.Properties, key); ok {
+			itemConfig[key] = stringifyAny(v)
+		}
+	}
+
 	// Pre-resolve any datasource-typed sub-property the MDL set, so attribute
 	// sub-properties later in the loop resolve against the item's own entity
 	// regardless of schema property order. The built DataSource is emitted in
@@ -934,7 +981,8 @@ func (e *PluggableWidgetEngine) buildObjectListItem(mapping *ObjectListMapping,
 			// gate + dataSource binding. Scoped to chart series so non-chart
 			// object lists (Accordion groups, DataGrid columns) are untouched. (9a)
 			if ip.Operation == "texttemplate" && isChartSeriesContainer(mapping.MDLContainer) &&
-				chartSeriesTextTemplateVisible(ip, itemDataSetMode, prebuiltDataSources) {
+				chartSeriesTextTemplateVisible(ip, itemDataSetMode, prebuiltDataSources) &&
+				!chartSeriesTextTemplateHiddenByItemConfig(ip.PropertyKey, itemConfig) {
 				spec.Properties = append(spec.Properties, backend.ObjectListItemProperty{
 					PropertyKey:   ip.PropertyKey,
 					Operation:     "texttemplate",