fix(pages): container names in item slots (#2109) and bindings through an outer data view (#2107)

.claude/skills/fix-issue/findings/mdl-executor/2026-11-11-binding-through-outer-data-view.json

@@ -0,0 +1 @@
+{"area": "mdl/executor", "date": "2026-11-11", "refs": ["ako/mxcli#2107", "ako/mxcli#826", "ako/mxcli#833", "mendixlabs/mxcli#1591"], "ce": ["CE7247"], "symptom": "describe page -> exec of six FactoryManagement pages (Mendix 11.16) failed: a markdown viewer in an inner data view was refused \"`GenAICommons.Span.Output` is an attribute of GenAICommons.Span, not of ConversationalUI.CopyHelper … CE7247\" (and Span_TextGeneration_SlideIn's markdownViewer3 failed \"failed to resolve mapping for stringAttribute\"); an attribute-based visibility condition failed \"ConversationalUI.TraceView has no attribute HasError\".", "file": "mdl/executor/cmd_pages_parameter_binding.go (namedObjectSourceName, isNamedObjectAttributeText), cmd_pages_describe_pluggable.go and cmd_pages_describe_parse.go (print $dv.Attr / $dv/Assoc/Attr), cmd_pages_builder_v3.go (namedObjectVariable, used by resolveRootedAssociationPath), widget_engine.go (parameterBinding takes a data view; rootedAttributeBinding; BuildContext.AttributeSteps), widget_expression_value.go and validate_widget_expression_value.go (rooted data-source form on an attribute property), cmd_pages_builder_visible_when.go, cmd_pages_input_binding_context.go (MDL-WIDGET34 accepts an enclosing data view), mdl/backend (WidgetObjectBuilder.SetAttributeWithSteps in widgetobj and mcp). Tests: cmd_pages_outer_dataview_binding_2107_test.go", "cause": "Studio Pro stores both bindings with the data-view pair SourceVariable {Widget: <outer data view>, PageParameter: …} (markdownViewer3 also with association steps). parameterSourceName returns \"\" when Widget is set, so describe fell back to the qualified name and the rewrite resolved it against the nearest container. The `$dataView1.Attr` spelling existed for built-in inputs only (#826); the pluggable engine, Visible-by-attribute and MDL-WIDGET34 accepted a parameter only, and no pluggable attribute property could store association steps at all.", "insight": "**When a describe falls back to a qualified name, look for a SourceVariable the reader ignored.** Every one of these bindings carried the pair, and the existing spelling for it just had not been wired into every reader and writer: grep the parameter-only helpers (parameterSourceName, parameterVariable) for their callers, and widen them in ONE helper (namedObjectVariable, namedObjectSourceName) so check, describe and exec agree. Also note that `$x/Assoc/Attr` parses as an association data source, not an expression: a fix tested only through the expression form passes its unit test and still fails the real page (MDL-WIDGET42) - feed the engine the parsed shape. Controls: reverting each edit fails its test; the old binary refuses all six pages, the new one reports Unchanged page on all six; a fresh page with $dvOuter.Output, $dvOuter/Span_Trace/SystemPrompt and Visible: $dvOuter.Flag in (true) builds with mx check 0 errors on 11.16."}

.claude/skills/fix-issue/findings/mdl-executor/2026-11-11-own-container-name-in-item-slots.json

@@ -0,0 +1 @@
+{"area": "mdl/executor", "date": "2026-11-11", "refs": ["ako/mxcli#2109", "mendixlabs/mxcli#1324", "mendixlabs/mxcli#122", "ako/mxcli#2095"], "ce": ["CE0117", "CE0115"], "symptom": "describe page -> exec of four FactoryManagement pages (Mendix 11.16) was refused by check on its own output: \"`actionButton1` reads `$grid1` …, but `grid1` is the data container the widget sits in directly\" (MDL-BUTTON02) and \"$grid1 cannot be stored — … an explicit one is rejected as CE0115\" (MDL-PAGEARG01). The stored pages build (untouched app: 4 unrelated errors).", "file": "mdl/executor/validate_page_button_context.go (checkButtonContextTree: control bar nearest \"\", nearestSelectable; isObjectContextContainer + combobox; checkOwnContainerName skips a show page in a selectable grid's rows), mdl/executor/cmd_pages_showpage_args.go (pageArgContext.rowSelectionOf, namesRowSelection, selectableDataGrid, enteringDataWidgetOf shared by argContextForChildren and both engine sites), mdl/executor/widget_engine.go. Tests: validate_own_container_slots_2109_test.go; updated validate_page_own_container_name_test.go (btnCtlBar) and cmd_pages_showpage_selection_arg_122_test.go", "cause": "Three slots open or move an object context that the walks modelled wrong. A selectable data grid's name is its selection in its rows as well as its control bar (Studio Pro stores Variable {Widget: grid1} from column content). A control bar takes its object from above the grid but sits INSIDE it, so the container above is an outer one, not the nearest. A combo box's option content is its own item context. And the pluggable engine entered a data widget's argument context with its own constructor, so a fix in argContextForChildren alone left exec refusing what check accepted.", "insight": "**Dump the stored slot before deciding which side is wrong, and find the property path, not just the widget.** A small walker mapping each CustomWidget TypePointer to its PropertyKey showed `Datagrid:grid1 > [columns] > [content]`, `[filtersPlaceholder]` (printed as controlbar) and `Combobox > [optionsSourceAssociationCustomContent]` - three different reasons in one rule. Then **re-measure an old 'measured' verdict with today's writer before trusting it**: btnCtlBar's CE0117 on 11.14 was an error in an EXPRESSION `$dvP`; since #2095 the argument is written as the variable pair, and a probe on 11.16 builds it - and even a button DIRECTLY in dvP passing $dvP - with 0 errors (positive control in the same build: CE1365), so MDL-BUTTON02's premise for action arguments may be stale beyond this fix. Controls: reverting each of the five edits fails its test; old binary refuses all four pages, new one reports Unchanged page on the three that MDL-WIDGET03 (#2110) does not block."}

CHANGELOG.md

@@ -27,6 +27,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ### Fixed
 
+- **`check` accepts the data-container names Studio Pro stores in a grid row, a control bar and a combo box option** (ako/mxcli#2109) — `describe page` → `exec` of four FactoryManagement pages was refused on its own output (MDL-BUTTON02, MDL-PAGEARG01): a show page in a selectable data grid's column passing the grid's selection (`$grid1`), a control-bar button passing the data view around its grid, and a combo box's option content reading the data view around the combo box. All three build in Studio Pro's own pages. `check` and `exec` now accept them and write what Studio Pro stores, and the pages report `Unchanged page`.
+- **A binding to an outer data view keeps that data view** (ako/mxcli#2107) — a markdown viewer or an attribute-based visibility condition inside a nested data view, bound to the outer one's object, was described as a bare qualified name and rewritten against the nearest data view: CE7247, or "has no attribute". `$dvOuter.Attr` and `$dvOuter/Assoc/Attr` now work on a pluggable widget's attribute property and in `Visible: … in (…)`, as on input widgets, and `describe` prints them; the six FactoryManagement pages report `Unchanged page`.
 - **`describe page` → `exec` no longer rewrites a page over formatting and stored keys MDL cannot state** (ako/mxcli#2106) — on FactoryManagement, 8 pages reported `Replaced page` with nothing changed: a dynamic-classes expression's trailing newlines, an XPath constraint's line breaks and spacing, the order of an enumeration condition's values, an association source's null `SourceVariable` key, and an inherited `createdDate` binding requalified to the specialization. The stored value is now kept where only its form differs, the writer stores the key Studio Pro stores, and a system member resolves to the entity that stores it. A full sweep of the app's 229 pages turns those 8 `Unchanged` and changes no other.
 - **`describe page` → `exec` keeps a check box's label position, a radio button group's orientation and a show page action's close count** (ako/mxcli#2106) — none had an MDL spelling, so a round trip of a Studio Pro page reset a check box with its label after the control to the default, turned every vertical radio button group horizontal, and stopped a show page button from closing the page it came from, with `mx check` green. `checkbox` takes `LabelPosition: Default|BeforeControl|AfterControl`, `radiobuttons` takes `RenderHorizontal: false`, and `show page` takes `with (NumberOfPagesToClose: n)`; `describe` prints each when it differs from the default.
 - **`mxcli test --local --watch` keeps applying changes on macOS and Linux mxbuild** (mendixlabs/mxcli#1787, refs mendixlabs/mxcli#1786) — the test runner's rebuild called mxbuild's serve process directly, without the recovery `run --local --watch` has, so the second build of a serve process failed on regenerated pages and every later change reported "could not be applied". The rebuild now goes through the same recovery, which also recognises mxbuild's resource-key form of that failure (`IO_PathNotFound_Path`, as macOS and Linux report it) and skips the web-bundle check, which only matters when a browser is served.

docs-site/src/reference/page/create-page.md

@@ -238,7 +238,14 @@ DATAGRID dgOrders (DataSource: DATABASE FROM Sales.Order, Selection: Single) {
 
 A `SHOW PAGE` in the control bar takes the selection the same way —
 `Action: SHOW PAGE Sales.Order_Detail(Order = $dgOrders)` opens the page with
-the selected row, and the button is disabled until a row is selected.
+the selected row, and the button is disabled until a row is selected. In a grid
+with `Selection`, a `SHOW PAGE` in a column's custom content may pass the
+grid's selection by name as well, which is what Studio Pro stores there;
+`$currentObject` is the row.
+
+A control bar takes its object from above its grid, but sits inside the grid,
+so the data view around the grid is an outer one there: `$dvOrder` from the
+control bar of a grid in data view `dvOrder` is valid.
 
 `mxcli check -p <app.mpr>` reports a missing argument before mxbuild does.
 
@@ -288,6 +295,14 @@ attribute property set by its own key too, such as a Custom chart's
 attribute (`Module.Other.Attr`) is refused, because stored without the
 parameter it is mx check CE7247.
 
+An **enclosing data view** is named the same way: inside a data view nested in
+`dvOuter`, `$dvOuter.Attr` reads the outer data view's object, and
+`$dvOuter/Assoc/Attr` reads over an association from it. This works on input
+widgets, on a pluggable widget's attribute property
+(`markdown md (stringAttribute: $dvOuter.Output)`) and in an attribute-based
+visibility condition (`Visible: $dvOuter.HasError in (true)`). It is the form
+Studio Pro stores for these bindings.
+
 ## Parameters
 
 `module.Name`

mdl-examples/bug-tests/2107-binding-through-outer-data-view.mdl

@@ -0,0 +1,51 @@
+mdl 1;
+-- ============================================================================
+-- Bug ako/mxcli#2107: a binding to an outer data view resolved against the nearest
+-- ============================================================================
+--
+-- Symptom (before fix): describe page -> exec of six FactoryManagement pages
+-- (Mendix 11.16) failed. Studio Pro stores the binding with the data-view pair
+-- SourceVariable {Widget: <outer data view>, PageParameter: …}; describe printed
+-- the bare qualified name and the rewrite read it against the NEAREST data view:
+--   "`GenAICommons.Span.Output` is an attribute of GenAICommons.Span, not of
+--   ConversationalUI.CopyHelper … CE7247" (markdown viewer)
+--   "ConversationalUI.TraceView has no attribute HasError" (Visible by attribute)
+--
+-- After fix: `$dvOuter.Attr`, and the rooted `$dvOuter/Assoc/Attr`, on a
+-- pluggable widget's attribute property and in `Visible: … in (…)`, store the
+-- data-view pair (with the association steps); describe prints them so, and
+-- the six pages report `Unchanged page`. mx check 0 errors on Mendix 11.16.0
+-- for this script (needs the Markdown widget, as Conversational UI ships it).
+--
+-- Usage:
+--   mxcli exec mdl-examples/bug-tests/2107-binding-through-outer-data-view.mdl -p app.mpr
+--   mxcli docker check -p app.mpr        -- expect 0 errors
+-- ============================================================================
+
+create module BugTest2107;
+create module role BugTest2107.User;
+
+create persistent entity BugTest2107.Span (Output: String(unlimited), Flag: Boolean default false);
+create persistent entity BugTest2107.Trace (SystemPrompt: String(unlimited));
+create association BugTest2107.Span_Trace from BugTest2107.Span to BugTest2107.Trace;
+create non-persistent entity BugTest2107.Helper (Note: String(100));
+
+create microflow BugTest2107.DS_Helper () returns BugTest2107.Helper
+begin
+  $Helper = create BugTest2107.Helper (Note = 'x');
+  return $Helper;
+end;
+grant execute on microflow BugTest2107.DS_Helper to BugTest2107.User;
+
+create page BugTest2107.Span_Details (Params: ($Span: BugTest2107.Span), Title: 'Span', Layout: Atlas_Core.PopupLayout) {
+  dataview dvOuter (DataSource: $Span) {
+    dataview dvInner (DataSource: microflow BugTest2107.DS_Helper()) {
+      markdown mdOutput (stringAttribute: $dvOuter.Output)
+      markdown mdPrompt (stringAttribute: $dvOuter/Span_Trace/SystemPrompt)
+      container cFlag (Visible: $dvOuter.Flag in (true)) {
+        dynamictext txtFlag (Content: 'flagged')
+      }
+    }
+  }
+};
+grant view on page BugTest2107.Span_Details to BugTest2107.User;

mdl-examples/bug-tests/2109-own-container-name-in-item-slots.mdl

@@ -0,0 +1,64 @@
+mdl 1;
+-- ============================================================================
+-- Bug ako/mxcli#2109: check refused Studio Pro's own data-container names
+-- ============================================================================
+--
+-- Symptom (before fix): describe page -> exec of four FactoryManagement pages
+-- (Mendix 11.16) was refused by check on its own output:
+--   "`actionButton1` reads `$grid1` …, but `grid1` is the data container the
+--   widget sits in directly — its name is a variable only inside a data
+--   container nested below it (CE0117)" [MDL-BUTTON02]
+--   "$grid1 cannot be stored — … an explicit one is rejected as CE0115" [MDL-PAGEARG01]
+-- The stored pages build. Measured shapes:
+--   - a button in a SELECTABLE data grid's column passing `$grid1`: Studio Pro
+--     stores Variable {Widget: grid1}, the grid's selection, as from its
+--     control bar (MxModelReflection.MxObjectType_Select);
+--   - `$dataView3` from the filter bar (control bar) of a grid inside dataView3
+--     (OIDC.OIDC_Client_NewEdit): the bar sits inside the grid, so dataView3 is
+--     an outer container there;
+--   - `$dataView2` in a combo box's option content inside dataView2
+--     (AgentCommons.Version_NewEdit): the option is the combo box's own context.
+--
+-- After fix: check accepts all three; exec writes the variable forms Studio
+-- Pro stores; mx check 0 errors on Mendix 11.16.0 for this script.
+--
+-- Usage:
+--   mxcli exec mdl-examples/bug-tests/2109-own-container-name-in-item-slots.mdl -p app.mpr
+--   mxcli docker check -p app.mpr        -- expect 0 errors
+-- ============================================================================
+
+create module BugTest2109;
+create module role BugTest2109.User;
+
+create persistent entity BugTest2109.Gate (Name: String(100));
+create persistent entity BugTest2109.Item (Name: String(100));
+
+create microflow BugTest2109.ACT_Open ($Gate: BugTest2109.Gate) returns Boolean
+begin
+  return true;
+end;
+grant execute on microflow BugTest2109.ACT_Open to BugTest2109.User;
+
+create page BugTest2109.Item_Details (Params: ($Item: BugTest2109.Item), Title: 'Item', Layout: Atlas_Core.PopupLayout) {
+  dataview dvItem (DataSource: $Item) {
+    dynamictext txtName (Content: '{1}', ContentParams: ({1} = Name))
+  }
+};
+grant view on page BugTest2109.Item_Details to BugTest2109.User;
+
+create page BugTest2109.Overview (Params: ($Gate: BugTest2109.Gate), Title: 'Overview', Layout: Atlas_Core.PopupLayout) {
+  dataview dvGate (DataSource: $Gate) {
+    datagrid dgGates (DataSource: database from BugTest2109.Gate) {
+      controlbar {
+        actionbutton btnOpen (Caption: 'Open', Action: call microflow BugTest2109.ACT_Open(Gate = $dvGate))
+      }
+      column (Attribute: Name)
+    }
+  }
+  datagrid dgItems (DataSource: database from BugTest2109.Item, Selection: Single) {
+    column (Attribute: Name, ShowContentAs: customContent) {
+      actionbutton btnView (Caption: 'View', Action: show page BugTest2109.Item_Details(Item = $dgItems))
+    }
+  }
+};
+grant view on page BugTest2109.Overview to BugTest2109.User;

mdl/backend/mcp/widget.go

@@ -165,6 +165,17 @@ func (w *mcpWidgetBuilder) SetAttribute(propertyKey, attributePath string) {
 	}
 }
 
+// SetAttributeWithSteps: the MCP payload's attribute has no association
+// steps, so a path over associations is reported unsupported rather than sent
+// as a direct attribute.
+func (w *mcpWidgetBuilder) SetAttributeWithSteps(propertyKey, attributePath string, steps []pages.AttributeRefStep) {
+	if len(steps) > 0 {
+		w.note("SetAttributeWithSteps(" + propertyKey + ")")
+		return
+	}
+	w.SetAttribute(propertyKey, attributePath)
+}
+
 // SetSourceVariable: the MCP widget payload has no slot for a property's
 // parameter source, so a `$Param.Attr` binding is reported unsupported rather
 // than sent as one read from the enclosing object.

mdl/backend/mutation.go

@@ -392,6 +392,10 @@ type WidgetObjectBuilder interface {
 	// and deferred to Finalize, which returns the aggregate result.
 
 	SetAttribute(propertyKey string, attributePath string)
+	// SetAttributeWithSteps is SetAttribute for an attribute reached over
+	// associations: the AttributeRef's EntityRef holds one step per hop, as
+	// a rooted path `$Name/Assoc/Attr` stores it beside its SourceVariable.
+	SetAttributeWithSteps(propertyKey string, attributePath string, steps []pages.AttributeRefStep)
 	SetAssociation(propertyKey string, assocPath string, entityName string)
 	// SetSourceVariable names the object an attribute or association property
 	// reads, when that is not the enclosing data context: a page or snippet

mdl/backend/widgetobj/builder.go

@@ -136,6 +136,15 @@ func (ob *Builder) SetAttribute(propertyKey string, attributePath string) {
 	})
 }
 
+func (ob *Builder) SetAttributeWithSteps(propertyKey string, attributePath string, steps []pages.AttributeRefStep) {
+	if attributePath == "" {
+		return
+	}
+	ob.object = updateWidgetPropertyValue(ob.object, ob.propertyTypeIDs, propertyKey, func(val bson.D) bson.D {
+		return setAttributeRefField(val, attributePath, steps)
+	})
+}
+
 func (ob *Builder) SetAssociation(propertyKey string, assocPath string, entityName string) {
 	if assocPath == "" {
 		return

mdl/executor/cmd_pages_builder_v3.go

@@ -2573,13 +2573,8 @@ func (pb *pageBuilder) resolveRootedAssociationPath(attrRef string) (wv pages.Wi
 	if !ok {
 		return pages.WidgetVariable{}, "", nil, false
 	}
-	var start string
-	if v, entity, isParam := pb.parameterVariable(root); isParam {
-		wv, start = v, entity
-	} else if v, isDV := pb.dataViewVariables[root]; isDV {
-		wv, start = v, pb.paramEntityNames[root]
-	}
-	if start == "" {
+	wv, start, named := pb.namedObjectVariable(root)
+	if !named {
 		return pages.WidgetVariable{}, "", nil, false
 	}
 	finalQN, steps, ok = pb.resolveAssociationPathFrom(path, start)
@@ -3017,6 +3012,27 @@ func (pb *pageBuilder) parameterVariable(name string) (pages.WidgetVariable, str
 	return pages.WidgetVariable{Variable: name, Kind: pb.parameterSlotKind(name)}, entity, true
 }
 
+// namedObjectVariable is parameterVariable widened to an enclosing data view:
+// the `$name` of a `$name.Attr` binding read from a page or snippet parameter,
+// or else from a data view the widget sits inside, whose SourceVariable is the
+// data-view pair {Widget: name, PageParameter: …} (ako/mxcli#826, #2107). It
+// returns the SourceVariable to store and the object's entity.
+func (pb *pageBuilder) namedObjectVariable(name string) (pages.WidgetVariable, string, bool) {
+	if wv, entity, ok := pb.parameterVariable(name); ok {
+		return wv, entity, true
+	}
+	name = strings.TrimPrefix(name, "$")
+	wv, known := pb.dataViewVariables[name]
+	if !known || pb.isDeclaredParameter(name) {
+		return pages.WidgetVariable{}, "", false
+	}
+	entity := pb.paramEntityNames[name]
+	if entity == "" {
+		return pages.WidgetVariable{}, "", false
+	}
+	return wv, entity, true
+}
+
 // documentKind names what is being built, for messages.
 func (pb *pageBuilder) documentKind() string {
 	if pb.isSnippet {