fix: set AttributeRef in ComboBox association binding

setAssociationRef only set EntityRef but not AttributeRef, causing the
association path to be lost in the BSON output. Also fixed
extractCustomWidgetAttribute to look up specific property keys
(attributeAssociation, attributeEnumeration) instead of returning
the first AttributeRef found, which could match CaptionAttribute.

Author: engalar

mdl/executor/cmd_pages_builder_input.go

@@ -172,14 +172,24 @@ func setDataSource(val bson.D, ds pages.DataSource) bson.D {
 	return result
 }
 
-// setAssociationRef sets the EntityRef field in a WidgetValue for an association binding
-// on a pluggable widget. Uses DomainModels$IndirectEntityRef with a Steps array containing
+// setAssociationRef sets both the AttributeRef and EntityRef fields in a WidgetValue
+// for an association binding on a pluggable widget.
+// AttributeRef stores the association qualified name (e.g., "Module.Order_Customer").
+// EntityRef uses DomainModels$IndirectEntityRef with a Steps array containing
 // a DomainModels$EntityRefStep that specifies the association and destination entity.
-// MxBuild requires the EntityRef to resolve the association target (CE0642, CE8812).
+// MxBuild requires both: association path in AttributeRef (CE8812) and
+// target entity in EntityRef (CE0642).
 func setAssociationRef(val bson.D, assocPath string, entityName string) bson.D {
 	result := make(bson.D, 0, len(val))
 	for _, elem := range val {
-		if elem.Key == "EntityRef" && entityName != "" {
+		if elem.Key == "AttributeRef" && assocPath != "" {
+			result = append(result, bson.E{Key: "AttributeRef", Value: bson.D{
+				{Key: "$ID", Value: mpr.IDToBsonBinary(mpr.GenerateID())},
+				{Key: "$Type", Value: "DomainModels$AttributeRef"},
+				{Key: "Attribute", Value: assocPath},
+				{Key: "EntityRef", Value: nil},
+			}})
+		} else if elem.Key == "EntityRef" && entityName != "" {
 			result = append(result, bson.E{Key: "EntityRef", Value: bson.D{
 				{Key: "$ID", Value: mpr.IDToBsonBinary(mpr.GenerateID())},
 				{Key: "$Type", Value: "DomainModels$IndirectEntityRef"},

mdl/executor/cmd_pages_describe_pluggable.go

@@ -7,30 +7,13 @@ import (
 )
 
 // extractCustomWidgetAttribute extracts the attribute from a CustomWidget (e.g., ComboBox).
+// Specifically looks for attributeAssociation or attributeEnumeration properties by key,
+// avoiding false matches from other properties that also have AttributeRef (e.g., CaptionAttribute).
 func (e *Executor) extractCustomWidgetAttribute(w map[string]any) string {
-	obj, ok := w["Object"].(map[string]any)
-	if !ok {
-		return ""
-	}
-
-	// Search through properties for attributeEnumeration or attributeAssociation
-	props := getBsonArrayElements(obj["Properties"])
-	for _, prop := range props {
-		propMap, ok := prop.(map[string]any)
-		if !ok {
-			continue
-		}
-		value, ok := propMap["Value"].(map[string]any)
-		if !ok {
-			continue
-		}
-		// Check for AttributeRef
-		attrRef, ok := value["AttributeRef"].(map[string]any)
-		if !ok {
-			continue
-		}
-		if attr, ok := attrRef["Attribute"].(string); ok && attr != "" {
-			return shortAttributeName(attr)
+	// Try association attribute first, then enumeration attribute
+	for _, key := range []string{"attributeAssociation", "attributeEnumeration"} {
+		if attr := e.extractCustomWidgetPropertyAttributeRef(w, key); attr != "" {
+			return attr
 		}
 	}
 	return ""